Chemical Weathering of Layered Ni-Rich Oxide Electrode Materials: Evidence for Cation Exchange

By I. Shkrob, James A. Gilbert, P. Phillips, R. Klie, R. Haasch, J. Bareño, D. Abraham. 2017

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Lithiated ternary oxides containing nickel, cobalt, and manganese are intercalation compounds that are used as positive electrodes in high-energy lithium-ion batteries. These oxides undergo changes, when they are stored in humid air or exposed to moisture, that adverselyaffecttheirelectrochemicalperformance.Thereisanewurgencytobetterunderstandingofthese“weathering”mechanismsasmanufacturingmovestowardamoreenvironmentallybenignaqueousprocessingofthepositiveelectrode.Delithiationoftheoxideandtheformationoflithiumsalts(suchashydroxidesandcarbonates)coatingthesurface,areknowntooccurduringmoistureexposure.Theredoxreactionswhichfollowthisdelithiationarebelievedtotriggeralltheothertransformations.Inthisarticlewesuggestanotherpossibility:namely,theproton–lithiumexchange.Wearguethatthishypothesisprovidesasimple,comprehensiverationaleforourobservations,whichincludecontractionofthe c -axis (unit cell) lattice parameter, rock salt phase formation in the subsurface regions, presence of amorphous surface films, and the partial recovery of oxide capacity during electrochemical relithiation. The detrimental effects of water exposure need to be mitigated before aqueous processing of the positive electrode can find widespread adoption during cell manufacturing. field field

Subfields: Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/55d2ed3ba56400265396f5154abf65ccffe5aa1f