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my it's my pleasure be here and thanks for coming so this is our collaborative effort between a bunch ofus at dalhousie and researchers at 3m andmedtronic energy and component center and e-one molienergy and in maple ridge and i would say thiscould this works been sorta going on since about 2008 roughly so here's a picture of the tesla model s motor trend car the year in 2013

seat seven people amazing car really very beautiful it's all-electric 265 mile range betweencharges cost about eighty five thousand dollars a lotof that cost it's in the battery and one the questions people have is even though the battery comes with aneight year warranty it's gonna be very expensive to replaceand you know how long will it last and what electric vehicle manufacturers and

lithium-ion battery makers makers knowis that lithium-ion batteries struggle when thetemperature is hot so this is gonna be perhaps problematicin hot climates and the first issue with lifetime upwith the mine batteries in electric vehicles has come up now in october up 2012 miss and leaf users in southern california and arizona sued near san class action lawsuitaccuse neshannock concealing leaf

vehicles have a design defect that caused them toprematurely lose battery life and driving range okayso these typed things you'll see on thisslide in the next few slides are directly cut and pasted of the of the lawsuitthat you can get online this and failed to disclose and orintentionally omitted to reveal a design defect in the leaf called the thermal management defectother electric vehicles

equipped with lithium-ion batteries areequipped with active thermal management systems on theideas to keep the temperature in the battery pack down ness and however opted not to include an active thermalmanagement system in the leaf lack of an adequate active coolingsystem cause the batteries to sufferheat-related damage causing premature battery capacity loss especially for those vehicles in warmclimates

which are losing over 20 7.5 percentbattery capacity within the first one or two years of operation soul that's not good so this a course result another reduction a driving rangeand what i want to do is to tell you why this is happening and what we can do about it but you gotta have some knowledge of howtemperature affects with you marry but barry lifetime andwhite lithium ion batteries fail anyway so here

is a graph taken from a lithium-ionbattery manufacturers website for lithium iron phosphate baselithium-ion cells and it just shows the capacity that thebattery delivers as a function of its charge/discharge cycles number for cells tested at room temperature at60 degrees c eighty-degree sienna hundred-degreesee-saw gets very hot but when you look at 60 degrees c 500cycles you've only lost 10 percent have thecapacity and in southern california and arizona

it's not sixty degrees c and even ifyou're charging and discharging the battery once per day in your ness and leaveyou're only gonna go 300 cycles in a year so how the heck could you possibly belosing 20 7.5 percent of the capacity in the first year mike doesn't makesense until you read the fine print and thefine print is right here at the top and how are these batteries tested allthis 1.5 c means

it was charged in about 40 minutes and this -2.5 see means it wasdischarged in about 20 minutes so each charge discharge cycle takesabout an hour maybe a little more so this entire task talk about 500 hoursor so okay so this experiment was done veryrapidly in a little a little less than a month if you take the same exact cell which comes from a 1-2-3 and you tested where you do a charge discharge thedischarge takes fifty six hours on a

charge 656 hours it's a red car you plot capacity versuscycle number you can see the thing dies really fastcycle count so this blue data is a 60-degree date ishowed you on previous slide and the red date is whathappens if you go much more slowly so the time a beachcycle takes much much longer okay so the the point is that you get a very lotta capacity loss percycle number when you go slow at high temperature because there's

there's chemical reactions going on inthe cell that are bad and when you do charge discharge rapidlyall you're doing is beating the clock you're beating the clock on thesetemperature-dependent time i these time-dependent parasiticreactions if you take the same data and plottedversus time so here's the blue data for the celts ican rapidly and here's the red for the cell cyclingslowly now they're showing more similar slopesmiss really tells you that you know the time of exposure hightemperatures very important to the

failure and it shows that sells have to becycled under realistic conditions to give a meaningful cycle and counterlife determination just as a point of interest these type abatteries are not used by tesla motors in in there their vehicle their use byfiske are and by tom gm minutes chevy spark so lifetime a valuation i've lithium-ionbatteries as

very tough problem because if you wannademonstrate an eight year warranty you go test for eight years on real realconditions are you gotta think of something else to do so what the battery makers generally dois they hide in the sand and they do cycle testing there by a whole buncha chargers andthey just put cells on task for long periods of time and it's like running sausages through asausage factory on you don't learn very much

while you're doing that and 2008 wedecided to really bite the bullet and invest thetime in a lotta resources to maybe figure something out in webuilt some very high precision electronics i'lltell you about that allow us to do om measurements in a short period of timethat allow us to project battery lifetime on the scale love years okay so i'm gonna talk to you aboutexperiments made an a a few different types of lithium

are based cells i'll talk about cellsthat have lithium metal negative electrode and agraphite pas graphite working electrode here this isto study the behavior the graphite electrode and i'll talk about sell to the left himat all negative and a with them transition metal oxidepossible electrode and that's to study the behavior the possum and then i'll talk to you about cellsthat have the graphite and the possible after thisis about a lithium-ion cell

kansas oven these are corn cells that wemake in our laboratory and a lot of the other things i'll tellyou when the lecture are on commercial lithium-ion cells made specially for us by differentcompanies all talk about the results on those two so first we gotta do is understand howlithium-ion battery works okay so here's a picture showing the positive electrode a lithium transition metal oxide on aluminumcurrent collector

and the graphite negative electrode on acopper card collector these two electrodes are separated byand electrolyte that contains dissolved let the mind andeach of these electoral materials is layered and their each intercalation compound and that means lithium atoms can residebetween the the layers and they can be d intercollegiate an interpolated whenthe batteries charging discharging and what's really important to recognizeis the intercalation andy intercalation

processes inc incredibly benign because a structuralchange up about 3 percent volume change in the positive and about10 percent in the negative and there's no structural degradationthat takes place in these materials and all the failure of the lithium-ion batteryreally has very little to do with structural degradation of the electrodematerials during the charge just charge cycling when the lithium-ion battery isassembled

the negative electrode is graphite thekind that would be in your pencil the possible electorate is alithium transition metal oxide that synthesized in the air at hightemperature it's stable in air so both electoral materials are stablein air you can build a batter in the open air soon as you put it together and start tocharge the battery you force electrons in this sense to the right my car spawning lithium-ionhops out into the electrolyte and moved to the graphite work itsintercollegiate that charges the

with the mind cell once a little mindsoul is charged now the lift the aidid graphite graphitewith lithium inside is very reactive reacted like with him at all and the with him transition metal oxide withmissing lithium is also very reactive and what happens is both are those realelectrodes actually react with the electrolytesolution that they're in contact with up and you would say well then how do youmake a battery that has he hiked time at all if the electrolyte

reacts with the electrodes but bylocking by chance min the reaction occurs the reactionproducts turn out to be solid on the negative electrode theformer pass a meeting film that slows down and limits for thereaction and on the possible actor on a similarthing happens so by locke these reaction don't destroy the battery in fact they form passer rating servicesthat allow them to operate for many many many months

but it's the formation of these on theseper and the it's the presence of these parasiticreactions that are bad and lead to the the failure lithium-ioncells so when you do testing ability mind sellthe so what you normally do your discharge it in your charges anddischarges charge it between fixed upper and lower voltage limits and you measure the capacity of the cellduring charge/discharge cycling so the capacity when you're doing thisexperiment a constant current is very easy to calculate it's theconstant current

times the time above the charge for thecharge cycle packages the charging capacity and the capacity and discharges the currenttimes the time in the discharge cycle i get to discharge capacity and for a perfect lithium-ion cell the charts absolved the livers and the charge that you store in thecell during the charges should be exactly the same so this ratio cool on the deficiency

ratio that charge the battery deliversto that which you store should be exactly one and if it is exactly one the lithiummine so will last forever but the point is because %uh theparasitic reactions between the electrode materials and the electrolyte the school on the deficiency is notexactly one okay and if you could measure the coolon the deficiency really accurately you could use it to tell the the magnitude of the parasiticreaction's going on into this

in the cell and that's going to be thethe point of this lecture is what can you learn if you measure thequality efficiency really accurately about cell lifetime okay so we gotta know a little bit aboutthe electrolyte in these batteries their typically carbonate organic carbonates likeethylene carbonate probably in carbonate i'm ethyl carbonate a metal carbonate typical battery electrolyte might bewith him foster attacked the floor dissolved in amixture of these solvents

the solvents are mixed because someother time have much lower boiling points and give good low temperature performance some ofthem form very good passer rating layers on thenegative electrode so using a mixture tends to havebenefits as i mentioned when the graphite becomes intercollegiate with lithium and it'sexposed to electrolyte it reacts with the electrolyte and afilm a reaction product form on the surface

and it's called the solid electrolyteinterphase or sci and this is a picture from a paper byemmanuel pallid showing the sort of structure of theseri it's a heterogeneous mass comprising inorganicand organic components but anyway as this thingforms it slows down the reaction between thelithium in the carbon and the electrolyte solution so you can take a look at this reaction between a with him in thegraphite and the electrolyte solution by

studying a lithium metal versus graphite cell whoops so in this lower panel now i've plotted the voltage a bullet in graphite cell asyou add lithium to the graphite and then move remove itagain it goes back and the voltage comes up again but ifyou notice you don't come back to zero on thecapacity access that's because some other lithium thatyou've transferred to the graphite side has reacted

and warm the solid electrolyteinterphase some other components and that's allelectorate interface or lithium oxide lithium carbonate they trap lithium atoms so when you comeall the way back the graphite is emptier lithium put someon the left email you added is in that asean doesn't come out comeback and as you charge and discharge repeatedly this voltage curve keep shifting to theright always and that comes about because someother lithium is being trapped in that

sci film so in this inside panel i just show youwhat's happening at cycles 15 10 15 and 20 to the top of charge in the bottom discharge they keep moving to the righthe moving to the right and the rate of motion slows down as the film gets thicker and moreprotective in the top panel here i'm plotting the discharge and point capacity so thepoint

at the end of discharge as a function ofthe cycle number in the black dots you can see it increases rapidly andthen starts to slow down and the top of charge has exactly the same behavior it movesrapidly at the beginning and then starts to slow down okay as the film thickens and becomesmore protective we call this motion charge and discharge and point capacity slippage case werecalled slippage because this

is slipping to the right case all talkabout slippage from time to time okay so you can learn about theseparasitic reactions by carefully keeping track up to and points and how they slip and thepositive electrode shows a similar issue so here's possible electrode and when that electrogets charged the voltage goes quite high 4.2 4.3 vaults verses withthe metal to very oxidizing condition and electrolyte can be oxidized i justshow its kamat aqui by electrolyte with a plus there and thereason i show it like that is

don't think anybody really knows whathappens in detail anyway then this oxidize electrolytemight migrate over to the negative where it gets reduced and form some film reaction product that's just onescenario that might happen and here we're gonna just look at a lithium metal verses lithiumtransition metal oxide cell again that's being charged thats removing the pm making thematerial more oxidizing and add the lithium back net doesn'tcome all the way back to the access

and every time you charge and dischargethe curve keeps shifting to the right more and more electrolyte gets oxidized and that oxidation electrolyte cause thecharge imbalance between charge and discharge and the endpoints keep shifting to the right and unlike the negativeelectrode side this shifting doesn't doesn't seemto slow down okay it just keeps increasing so thesereactions between the electrode materials in the electrolyte the

that bad it's bad and temperatureaggravates those reactions so just to remind you these parasitic reactions that are going on in the cell their badand by measuring the cuyamaca financier thecell you can quantify the amount of parasiticreactions that are going on in the cell what you got a measure the cool on theconfusion see very accurately because it's very close to one in good-looking my in cells

if you wanna lithium-ion cell the last10,000 cycles for grid energy applications it would need acool on the cover since you have at least 99.99 percent that means if you wanna make statementsabout a lifetime upsells based on quanta efficiency measures yougot a measure at least to the fourth digit inaccuracy in person precision but charger systems that you buy can'tdo this so these two guys here took on thechallenge of building a device could measure quantum golombekefficiency very accurately

and aaron smith is now at tesla motors in charger their battery lifetime groupgraduate in 2012 and chris is still my group are workingon this project and they've done a really nice job and this is a picture the machine thatthey built it saw a sixty channel high precision chartersystem each of these brown boxes that you seeis a precision current supply that supplies current up with five digits up precision

to a cell under test the seller testsour house in these temperature control boxes so that the temperatures very stable andyou can measure the charge and discharge capacities veryaccurately everything's computer-controlled the currents that these things outputeven though they're very accurate and stable we still pass those currents through precisionresistors at the top with these racks and measure the voltage on the precisionresistors to keep track of the current

really well and with this device we can measure coolon the confusion see very very accurately i'll just show you some simpleexperiments teach you about ness am leaf okay so these are experiments done oncommercially made what are called 18 650 size cell eighteen 650 sellers 18 millimeter diameter sixty fivemillimeter long exercising your finger roughly cellslike that are made at a rate of about $3

billion per year and they're used in low-end laptopcomputers okay so here we are were cycling thecells at 60 degrees c soul very hot and we're measuring cool on thedeficiency versa cycle number and cells are being cycled at threedifferent rates see over 24 means a charge in 24 hours in a discharge in24 hours see over 50 means fifty hours for acharge in fifty hours for discharge in see over 100 and 200 hours and there'stwo cells being measured in each of these testsand i just draw your attention to the

scale the cuyamaca efficiency at access and up accuracy of the data and the lack of scatter in most to thedata and obviously if you're takes twohundred hours for cycle you're going to get a data point every 200 hours in these bold crosses takes 100 hours for cycle toll cycle atthe over-fifty you get a data point every 100 hoursokay so you can you can notice that thecoloma efficiency the cells

depends on the charge discharge rate the reason for that is it takes longerfor a cycle means is more time for the parasiticreactions to to take place when you go slower and if you instead plot the cool omicsinefficiency just one minus the ce so just put thedata over and then take a look carefully you'llnotice that the coup la mic inefficiency scale 12 to24 just like the cycle times do

and if you divide one minus the climateefficiency by the time of a cycle all the data falls on universal car case was telling you that time exposure is really the bad actor here in the failure the cells at elevatedtemperature and now these measurements can be usedto rank all lithium-ion technologies i'll just show you some othermeasurements and it's a busy slide by the

easy to understand what you look at it okay so there's data here for 30 36 else in this panel lithium cobalt oxidelithium-ion cells running at three different rates arebeing characterized and it's one minus the cuyamacaefficiency over the time over cycle as at 30 degrees c so as we go from column the column wechange to nickel cobalt manganese lithium-ion cell

with your mind phosphate lithium-ioncell lithium manganese oxide lithium-ion cell and you can look and say well look atthese universal curves clearly a parasitic reactions are worsein this technology and then we done themeasurements at 40 degrees 50 degrees and sixty degrees c okay and if you were gonna select thelithium-ion cell for a hot climate up would you select this one if you work ina thermally manage it

or would you select this one or that one okay so what did miss an solak sonesta ness san selects a bland about fifty percent ofthis and fifty percent of that in their cells and so does gm in thechevy volt ness and does not temperature controlthe battery pack lots a parasitic reaction's going on atelevated temperature gonna lead early cell failure gm doestemperature control their battery pack and they're sold are their packs alasting longer than this and under high

temperature condition fiske are another poor choice and tesla has selected chemistries like lithiumcobalt oxide better very good okay so these precision cool on the treeexperiments you can't you know you you look at themthis way and the tell you a lot about complete competingtechnologies whereas you know a battery maker or a taserwithout access to this data have to test for a long time to come tothese kinda conclusions about

the severity of the parasitic reactionsare the different technologies alright so now i wanna use this equipment to start talkingabout okay with the mines fail what are we gonna do about it you know how we're gonna make thembetter and i want to talk about what are called electrolyte additives so every look in mind so that you usebeat in your phone or in your laptop or tablet or whatever it is themanufacturer has put in the electrolyte some chemicals like secret sauce thatimprove the life time %uh that sell

they're called additives and the mostfamous is violin carbonate and it causes less electro in oxidationon the positive electrode i'll show you in the next few slides people add additives that reducethe impedance themselves and limit gassing in cells they and wetting agents because thetrying to feed them through the manufacturing pop process as fast aspossible you at the electrode to the cell it hasto fill into these porous electrodes to add a wetting agent does that quicker

but how does that impact the celllifetime and all kinds of other things typical that the mind so might have fiveadditives in it for various purposes so here i'll just show you the impact a violincarbonate so here are lithium cobalt oxide graphitelithium-ion cells they're being cycle with the highprecision charging equipment so as you you can see the voltage capacity curveagain shifting to the right and this is causedby parasitic reactions taking place causing electrolyte oxidation thepossible electrode

things slipping to the right to sellmeasured at 40 degrees c but if you add violin carbonate to theelectrolyte back just stops okay so you really impact that parasitic reaction a lotwith 2 percent by weight have an electrolyte additive the samething happens at 60 degrees c there's a huge huge improvement in the in the rate ofelectrolyte oxidation the positive electrode side here some

other data this is for lithium cobaltoxide cells with no violin carbonate in theelectrolyte 1 percent and 2 percent and then lithium cobalt oxide cellscharged to a lower voltage and cells that have a nickel manganesecobalt possible electrode and why just wanna show you here is that when you look at the data you can see that even onepercent a violin carbonate really stops that slippage of the voltage curveto the right and the way that we look at these data

is not to look at curves like this butinstead to plot the charge endpoint capacity versa cycle number i'll show you that onthe next slide so here are the same cells on theprevious panel list with him cobalt oxide cells chargeto higher voltage in lower voltage wereplotting the charge endpoint capacity in percent versa cycle number so there's two cellshere in the crosses there's no violin carbonate at it andyou can see the end point slipping like

crazy to higher capacities when you add violincar made either one or two percent very much reduced if you look at the cuyamaca efficiencyand look at the scale here and look how repeatable the pair cellsare these are commercially made cellswithout violin carbonate the cuyamaca presidency is poor and with violin carbonate de quimicaprison see is much better and with the nickel manganese cobaltpositive electrode

up without finally car me this muchbetter situation why is that i don't know and adding bymarine carbonate improve the situation improve the situation over here but thereal take-home message here is if you measure capacity versus cyclenumber i defy you to tell the differencebetween these different electrolytes from these measurements thewhole look exactly the same you know and this is what traditionalbattery testing is all about you tried it tell what's going on fromdischarge capacity versus cycle number and you're forced to cycle toend-of-life

before you can tell what's going onwhereas these high-precision measurements candistinguish between good and last good very quickly so this is using your head and that's just sausage factory you know so we talk we've done this a few timeswhere we take our short term measurementscollected over a period of a couple weeks and then we take the cells and we've putthem on a dom charger

and run them for long periods of time sothis is twenty hours for every cycle 120 cycle so 2400 hours of testing and we increase the temperature too sothat we could distinguish more quickly the differences between the cells but you can see over here the cells thatare bass the pale symbol at the top i don't know what color it is cuz i'mcolorblind it could be anything sorta gray or pink or something likethat pale anyways the top one over here and thenthese blue symbols our next and their nexthere and the black is worst

and the red is next to the point is theshort term measurements bear out in the long term right so if you're somebody like me and you'retrying to make with the mind sold better you don't wanna test for a long periodof time you do these high precision measurementsand you can tell has the electrolyte additive help or hindered what you trying to do in here some data from medtronic for cells that are implanted in thehuman body to run up

pain a pain reliever all system and they have cells in the lab that are eight years of testingaccumulated at 37 degrees c so here you can see six to eight cyclesa day twenty thousand cycles eight years of testing at 37 degrees cthat's pretty impressive cells like this with nickel cobaltaluminum are in the tesla motors vehicle pesotesla motors uses technology that's at least this good this is eight year old technology writea test started eight years ago has to be

eight years old technology and how do you make it better well doyou wanna test for eight years to before you findout if it's better or not so medtronic's working with us to improve the cells and what we do iswe take their cells with differentelectrode additives that we and they specify and we measure the cool on rackinefficiency divided by the time of a cycle

and the data that i showed you on theprevious slide is for the additive sat in the blue box so we've identified additives that aremuch much better than the one in the blue box andmedtronic stake in the ones that at the bottom insert some salsa offerlong-term cycling and they'll of course be better than theones that you know that is so already demonstrateda years of testing so the point is in a few weeks you canidentify things that are way better than what is currently being used

now here comes the ultimate challengefor this method and that is that sometimes lithium-ioncells show this kinda failure that's incrediblyinsidious here so these are nickel manganese co all possibleelectrode with graphite negatives cells are cycling to an uppercut of afour-point 25 bolts and their look really really good and if you change the upper cut-offvoltage to 4.35 alt they start out looking really reallygood imagine this was in your car you say oh everything's great i love iti love it then all of a sudden you can't

even get out the driveway there is no way for lithium-ion batterymanufacturer to learn about when they get this rapidcatastrophic failure accept a cycle with until they get there and if this happens after three years orfive years you gotta you gotta go there to find it we believe that this roll over orcatastrophic failure comes about because up electrolyte oxidation at thepositive side there's no capacity fade significantlyhere at all

lithium is not getting consumed in scithe negative by contrast what's happening is theelectrolytes getting oxidized oxidation products moved to the negative and makecold across the service or the negative andeventually they shut the sell-down now if you charge to higher and highervoltage you accelerate electrolyte oxidation andthis catastrophic failure move to lower and lower cycle numbers as you can see to the point of this is this is a great test bad for our map it who long toconvince the measurement should capture

this and should be able to predict the onsethave catastrophic failure okay so we maiden did an experiment with you 1 malienergy in vancouver where they built a 160 18 650 cells for us and the cells had four cells have everytype with different electrolyte additives inthem sold for all the same except for electrolyte additives

and electrolyte additives are listed uphere the sea is violin carbon abc is finallyi think are really doesn't matter what these things are different electrolyte additives in use and the way the experiment went was we got to specify the electrodeadditives in a t-cells and they got to specify the electrolyteadditives in the other 80 cells and they didn't even tell us what theywere okay so they're additives are are thesenumbers whatever they might be

and are at it is are these known thingswhich i can tell you what they are but i'll tell you it doesn't matter for thepurpose of this talk and the point is take a look at thefirst 50 cycles and data look at the blown-up capacity scale can you tell me which are these aregonna fail first you can't right you have to cycle them to deathand we selected a design that will show thiscatastrophic failure now the don't describe to you how you designassault of a like that in a few minutes well i give you 100 cycles to look at

there's a 100 cycles now can you tell mewhich of these is gonna last long this year which is gonna fail first you can see one sonya drop out here nowat the bottom there okay so this is the problem you'retrying to improve lithium-ion batteries and you have to wait till the end of life before you knowwhich is better it's too small okay so how did the experiment go withthose guys so what happened the cells weremanufactured and then they were shipped to us forcycling on our high precision charger

and we also did some storage study so iwon't talk about so they came to us and we gave themsixteen cycles on the high precision station and here i'm showing you datafor five different electrolyte additivemixtures so for them are known to this to you bemeans to unknown to plan b okay but you can seethe call on the commission sees on this scale vary so fec is worse andthen vc then vc possibly see you then to ub and then these done then these trianglesup here quite a variation

then after we tested them we don't havethe resources to do all this long-term testing a takes a year or so we sentthem back to the manufacturer for their long-term testing long-term testing was done at to ampdischarge and two ap constant current constantvoltage charge so see rate further battery people and we continue thetasing till the cells reached 1.6 am powers so on the blue boxes where thetesting was done at the manufacturer so you look here at the first 50 cycles you'd say well the diamonds are lookinbast

and maybe maybe the crosses but when the cycling continues thecrosses die first and the diamonds hard far after and if you look at that high-precisioncycling day to look at that well the crosses should i first and they do andthe diamond should die nackte than they do in the squares and circles andtriangles being me being me being okay so it'sreally what you want so how do you design a cell to make itdo this

well if the reason the cell show thisdramatic rollover catastrophic failures because electrolyte oxidation productsmigrate to the negative where the reduced and eventually shut down the negativeelectrode what would happen if you really highly compact thegraphite particles in the negative okay so here prime have a cartoon thisis a negative electrode it's made of graphite particles it's been highly compact it so theporosity is pretty small your cycling the cell you gettingelectrode oxidation products to come

across may get over there they see a lowpotential service at the front on the electrode and they get reduced inform some solidified jump there and the cell capacity is not going downvery much and your cycle so more and the layer john gets thicker and thepoor opening start to gets closed off and your cycle so more and the pores ultimately become filledand now it's very hard for the lithium

ions to penetrate into the back at theelectrode because it's blocked and then lithium plating begins on theservice and the capacity dies okay so that's what we believehappens when you take the cells apart at the end of life you see a lot of evidence from with himplaying in certain parts of the if you had a more porous negativeelectrode what what happened then well the to get the same scenariohappening same scenario happen but the poor don'tclose and if you make the same cells with lesscompact that negative electrodes they

don't show the catastrophic failure thefailure looks like this okay but it's still bad for theelectrolyte oxidation a going on because you're losing electrolyte okay so let's go back to our scenario let's say that we need a certain amount of fillmaterial to block these pores and let's say that on every chargedischarge cycle $1 -2 cool on the competency measureshow much electrolyte oxidation products moved from one side to the other

well if you get this much material onevery cycle and you need a constant about a materialto block the pores than one minus ee times a number ofcycles to failure should be a constant this constant isgonna be proportional to the thickness of the film needed to block those pores so what you need to do is plot a graphof number of cycles to failure verses 1over $1 -2 c and see what you get so we did this

here's the cycles to 1.6 am powers verses 1 over $1 -2 cool %ah makeefficiency and as a priest pretty decent straight-line agreement here for theelectrolyte additives that we know what they are it look pretty good there some of themoff the line but really is only two sets are three sets that aresignificantly of the line it's pretty amazing nobody's ever donethis kind of thing ever before and if you look at the positiveelectrode by asem

i just picked one other cells with thecvc an fec after 49 20 cycles it failed before the cycling and after the cycling positive electrode looks exactly thesame and if you look at the negativeelectrode before and after you can see the buildup of this film i've reaction products on theservice or the negative so the square region has been expanded over here you see all the skunk on theservice or the negative

and that's what leading to the thefailure of the cell okay sol what about their additives where theyfall on the graph i showed you the additives that wespecified not change the scale because the battery manufacturers are a lotsmarter than university professors and that's where there's fall sol you take a look at some of these thingsthey're cool on the deficiencies are similar you know to these guys butt bang thecycle life is way better

this for you a and five you a differ only by the addition i have oneadditive which is additive number five this has1234 this has one two three four five look at that incredible how does it work from 5 you a to the control with noadditives there's a 20-fold increase in cycle life just with a few percent up a few magicingredient that's amazing how does it work wirethese points

of our line well our model assume that any oxidation product goover to the negative informs followed products that block the serviceor the negative maybe when these guys go over they don'tform solid reaction products maybe they're liquids may be there gaseswho knows but then it wouldn't build up this filmup reactant reaction products that block thenegative so it's pretty mysterious here's a graphic kinda summarizes thatexperiment

see graph showing you along thedeficiency as a function of the number ofelectrolyte added to the cell so there were for cell types that had one electrolyte additive in 11cell types that had two and 10 that had three and three they had foreign onlyone that had five but you can see in general to call on the deficiency get better andbetter as you go and the corresponding cycles to failuregenerally

gets better and better as you go sosomehow these additives are acting in synergy in some way to improve things now if you read the academic literatureon electrolyte additives people study one additive at a time arethey gonna learn anything relevant i don't know because you have put a bunch a lament toreally do well and if you're not trying to figure outhow this works you're crazy because this is the easiest way to improve with the mindcell technology it's a way to really

improve it like crazy okay so people got interested in ourmethods i was lucky to get an automotivepartnership count a grand with a buncha credible partners and we've expanded our are high-precisioncharger facilities this system as a hundred channels thatcan do automotive scale lithium-ion cells and we're using with gm and magna totest theirselves this came operational in 20in april it's a pretty nice

nice system i wanna tell you one lastthing before we stop sometimes it's a problem working withindustrial partners you may know that if you're ever done it sometimes you would suggestan experiment we don't do that waz our resources and we say when thescientific value is important we gotta do it but our experiments on these highprecision cycle you need very repeatable to be able to say okay the differencebetween that sell and and that sells because of the electorate that have notbecause some graduate student made a

crappy cell more professor made a crappy cell yeah myself a really crappy so we wantto be free to do what we want machine-madecells so we've established some links with chinese battery makers who make pouchtype lithium-ion cells that we buy dry without electrolyte in and those come toaustin lot 2000 up the minimum i can buy 2000actually a pretty good number an a we bought a vacuum vacuum sealer sowe can see all these pouch cells

at dalhousie with whatever electrolytewe want so this is a big a big are big step for us and it's good really good what tell you what we'redoing with these things one experiment and that is any these parasiticreactions in a lithium-ion cell should make heatand if you use a very sensitive micro-cap our room matteryou should be able to see the heat okay so in our automotive partnership project webought this micro calorimeter from ta instrumentsit's an amazing device

has 12 calorimeter ports two contests 12 cells at once and we wire teacher theports so we can charge and discharge cellsdown in the calorimeter so nice of thermal calorimeter allexperiments were done at 40 degrees c and it measures the heat that thebattery is outputting more heat that's flowing into thebattery the machine works like a total charm and i can hold these outsells i'mtalking about. the sensitivity is 10 now know what's

and the baseline stability is betterthan 500 now what's over a month i'll tell you in a minute the concho inthe data how much heat to these pouch cells produce to the parasiticreactions so the heat that's given of an experimentlike this there's three sources when the lithium content in theelectrodes changes the entropy of the electrode materialschange and there's a heat flow associated with those entropy changes we're not interested in that and every battery has internal resistance or

hope polarization between charge anddischarge in the heat flow from that were not interested in that either the parasitic reactions to the electrodeelectrolyte reactions that's what we want to measure case we have to be other separate this from these other things that we don'twanna measure now what sorta scale of heat flow are we looking about hereso the cell store what our banerjee their 200 million powers at four bolts roughly what our and the energy insidethe complete electrolyte electrode

reaction turns out is also about what our that'sa rule of thumb for lithium-ion cells the electrical energy is equal to the chemical energy thatwould take place at the electrodes a lot reacting with the electrolyte so if up parasitic reactions occur at a rate thatwould consume all the electrolyte in a you get a hundred michael what's 200micro what's is bad you see a hundred michael what'sa parasitic reaction

that's very bad very very bad it so here's some experiments so these are identical pout cells withincobalt oxide graphite powder cells one has control electrolyte and theothers have different amounts a violin carbonate in them and they were the first charge anddischarge them one open circuit then we discharge them charge themdischarge and charge them and i we did a very slow charge anddischarge i wanna just concentrate on

this range if you look very carefully appear you'llnotice on the heat scale there's all kinds ofstuff happening entropy changes polarize asian and so onand so on but the cells are identical so the entropy changes should be thesame in all them the internal resistances are basicallythe same so the only difference between the heatoutput in the cells here is do the parasitic reactions

and the heat from the blue and black isless than the red it so this is a crappygraph right that's what you would put on your screen just to see what happen and when you look at this you say when ireally wanna do is plot the heat flow versus the voltage you do that what you get and i've added a data set forhalf-percent vc now as well okay so at low voltage 3.9 fault all the four cells are about the samethen there's a big entropy change due to

an order disorder transition withincobalt oxide but after that between 4.1 and 4.2vaults block here's no violin carbonate half percentless he to 14 percent less heat again and the the difference gets greater withvoltage so the violin carbonate the suppressing parasitic he do electrolyte oxidation wesaw lab early on from our charge that bitchmeasurement and you can see that at voltages above

4.1 balter saw the impact the bindingcarbon it starts to get very important look at the scale okay so this is from that tech marketthat is 200 microm what's so it's suppressing things by a borderover 100 micro what that's important so in a singleexperiment you can learn about thevoltage-dependent up the impact on the electrolyte additive or blend ofelectrolyte additives single experiment on how you can do thisany other way but it all relies on having access to i

down to call cells to do a measurementlike this pretty cool all rights all i'm done i'll just make a few remarkshigh-precision climb a tree and other methods like calorimetry will speeder development of advanced lithium-ionbattery longer lifetimes 3m's been a partner with us for a longtime but we're got more partners now in everybody's sees the value of these methods and restthe world's catching on

moving into this area too but really the main part of the product isanswering the question you know why do these additives lead to benefit somehowthey work and what is the service chemistry thattakes place and this is this is by far the hardest problem i've ever worked onin my life and all take the address to my careeryou noted maybe make some answers to this and idon't even know if we will but anyway we've got a couple techniqueslike this high precision cool on a tree in my crib calorimetry

and storage and impedance with servicescience measurements xps an ftir and other things that people wanna do to learn how these out its workand this is this is where my group is going now justanswer the why questions and not so you know we built thecharacterization tools from electrochemical point of view out time to do the hard stuff i thank you no you here about me

it based on the wall we bed naked buddy you have that show from themanufacturing their up on addition with him on so do you think good yup mile this is about the simplestmodel you can ever come up with him i thought without walking home one dayyou know i wasn't

writing fancy equations on theblackboard for years i'm a simple minded guy and i like simple stop so you you know whenyou do science is good to work with a working model in mind and you say well maybe the date is gonnafit this and if it doesn't then you have to say this is insufficient right she gotta gobeyond that and definitely you gotta go beyond that writer good

bar show you one thing i skipped overthis and the lecture so these guys here imagine that this one is not making solidreaction products on the negative three you we okay so what would the impedance of thatselebi like compared to these guys well there's nofilm of solids the impedance should be lower so we measured the impedance ofall the cells before we did before we send them backto the manufacturer for the long-term

cycling as i show the impedance of three you wecompared to everything else these are impedance spectrum of you'refamiliar with this but the thing that's important as thewith the semicircle here so look at three ue its the smallest byfarrah everything and if you look at the differencebetween 5 usa which is here and four you a which is here 5 you as alot less impedance and four you weigh and then you go back to the previousthing and here's for you a and a5 you is building last solidproduct on the surface that

do no less impedance there it is so ifyou make a 3d graph that improve includes the effectiveimpedance here one minus one over see if you go thatway things to get better and here's impedance if you go that waythings should get better and all the points fall on sort of a surface sup that guy is one out liar okay so ithink the missing ingredient here is is thesurface film on the negative are you making a solid service film or not andif you're not that's what you want you want that kindof an additive

you wanted limit the amount ofelectrolyte oxidation but you also want to make those solid product okay all long answer to question we we haven't done any work but these methods with the silicon inany great degree but you're right not different additivesare beneficial for silicon for sure than graphite mom no i don't think youneed to bring the power these methods to silicon at this pointso we can show so much

so much sci growth on every cycle because i love volume change that youcan see the parasitic reactions with a traditional charger pay your arm in our mac or whatever youmight have if you just have a lithium silicon cellgoing any measure keramik efficiency it'll be ninety-eight percent or 96 percent orwhatever it is a musher cycling really fast you need these fancy chargers forsilicon-based electrodes yet

there's there yeah you in the buying demi it does silicon is like light years away fromhaving lifetimes like these cells i'm talking about. siliconis light years away okay maybe in ten years it'll be you know thousand cycles on last a fewyears but its light years from there now curly

busted him stood lot much higher attentional see wherethe electorally actually forms actually where the likelyoxidize product ends up being reduced up at at everything what potential thatplus get against i'm lithium titanate is amazing well that's probably because it's i'mjust it's because the voltages hi i'm thethink i might have known that i don't have a within playmates light here

soul so are the best school or workefficiency numbers we get first see over 20 cycling at 40 degrees c for graphite negatives in with the mindset about 999 to will him tight nay we get and let your mind so we we get9999 a amazing lithium cobalt oxide with him tight natecells with going only a 4.1 bolt amazing to gonna last %um plant them in when thelast till she's dead

no doubt even in you the last time the dead eventhough you have a big advantage in years hit yeah bolt is our way through a like he's stews right side and angie day saudi i think the best this is this is what's gonna happen sowe're working with gm now

okay and it's an experience for mebecause gm doesn't make that the mine sells theybuy them so they haven't thought about you knowwhat all this stuff means too much and they want to do what your same sayokay the 8 the high person charged as this alsoon the drive cycles that his wife tell them is this what yougotta know what is a lifetime in your current technology and the tacit you currently ron okay then we do the measurements on yourcurrent technology

and whatever's coming next and we compare and we can tell youwhat's coming next is gonna be worse or better and make a projectionabout how much better okay but for me to go fromhigh-precision cycling data without any other knowledge topredicting wanna drive cycles gonna do impossible impossible now so gm sorry coming around now insurgency yeah i i'llpay yeah i see what you doing here you canalso do things like well what's the impact up a lifetime inthe drive cycle

you look at how the chronic efficiencyvaries with temperature and then you can get iran yes laws andwhatever and go back to the drive cycles that way soi don't really know how to answer your well today probably in a year or two these kinda things will have developedsomewhat yeah toward yes so services up although electrode in these things are all cycles you will so

it seems you battery testing that youuse like constant are great constant this he likemany for example drive the word holder tires child store seems to be a little more so you're your way down charging like only a year write me right sporadic day his best anything however his %um and are you

very his is my you rising at all i don't know the biggest the biggest issue is thetime spent at highest voltage the longer you spend at the highestvoltage the worse it is right you could see from the calorimeterexperiment things got worse you one up above 4.1 bolt so if you go to 4.2 worse than 4.1 yougot a 4.1 it's worse than for so the j the gm fault for example itcharges to eighty percent just 4.03 for that

cell decent not too much parasiticreaction's going on there okay but if it charge 200 percent would be worse okay so all cycles arenot created equal to answer your question the more timeyou spend at higher voltage the worse so you know i have cells from 1999 that were stored at about 20 percent state ofcharge so maybe three point by bolts for no cells put them on in 2013 mike new because

possible extra side not doing anythingbad at low voltage but they have been stored athigh voltage wouldn't have been nearly as good youlike a consumer education don't he topped off at all times well the the battery manufacturers way aroundthat is gonna be are yeah you know and select technologythat is ok at the voltage it's going to yeah so it's it's gonna be under controlpeople's or understand this yep yeah

yeah god there are no redox holes in in any of the cells in 10there are no intentionally added redox shuttles in any of the cells put it that way maybe some molecule getscreated in some funny way that you know lowers the chronicefficiency a little bit some shuttle action no i would say wheninterest is not waning at all arm you know the all the automakers have various thingsunderway

you know mercedes has the v's and d'salso in all it's tough going on at the same time bmw has you know biggie the project and thinkthe diesel guys are excited to gas geyser excited ev guys areexcited everybody's excited i i'm excited world dollar her him 22 sure yet first for sickos slightly to the leftand then a search going to the right

goes left first and then to the right well it's a pretty tiny tiny leftward shift in a pretty tinyrightward shift mean i can't this thirst storm do you know about overhangoverhang in with the mindset alls while the negative electrode is slightlywider than the positive okay that's because if the positiveelectrode were of a site opposite nothing you recharge to sellthe listing would come out an elector played on edge in thenegative and form with him at all

dendrites so the negative electrode iswider okay so then that means there's extragraphite or not out on the overhang so some a lift him from the positivegoes over there and you often get weird things happeningat the very beginning up cycling what's overhang equilibrate with the about upwith him in it very technical okay but when you look atthe bright fine scale like you're lookin things get technical i combination of both absolutely you know there's a lot of folks that arein the battery companies that just

test of i am what we've been starting to do justslightly higher level is scan to see which additives are working and say okaythere's a koran that like assault for double bonded to oxygen or assault for double bonded to two oxygensthat and then the russell a molecule you can you canchange in a systematic way and see what happens and there are people there doing theorywe need more people doing theory

yes better like all very for okay jockey percent don't or keep it as cool as possible at alltimes put in the frigid night then i won't bother you while you'resleeping too yeah added advantage now i'm serious ifyou keep any battery as cold as possible it willlast longer so any anne's with the mind cell keep inthe fridge when you're not using it last longer

if you if you don't charge a hundredpercent that will help but you know temperature is a bad actor keep in the fridge you don't mindcondensation on the keyboard when taken out i yeah hood yep yeah that's that stuff is not what iwould call sci hey this is the the reduced oxidation products come from the otherside it's junk

so that that that stuff you can see itwith an asean the normal sci what you would call sci is you know just a few nanometers thickyou can see it on an asi am at that this scale right so this is this isjohn that's come from the parliament beenreduced on the negative surface