Transition-Metal Dissolution from NMC-Family Oxides: A Case Study
Hannah R. Morin, D.G. Graczyk, Yifen Tsai, Susan Lopykinski, Hakim Iddir, Juan C. Garcia, Nancy Dietz Rago, Stephen E. Trask, LeRoy Flores, Seoung‐Bum Son, Zhengcheng Zhang, Noah M. Johnson, Ira Bloom
Abstract
We investigated the static reactions of highly delithiated Li(Ni1/3Mn1/3Co1/3)O2, Li(Ni0.5Mn0.3Co0.2)O2, Li(Ni0.6Mn0.2Co0.2)O2, and Li(Ni0.8Mn0.1Co0.1)O2 positive electrodes with 2,3-butanedione and with tetrabutyl ammonium bifluoride as model leaching agents. In the bifluoride trials, it was found that [Ni] in the leachate was proportional to XCo(XNi)3, where XM is the ideal stoichiometry in the bulk oxide, and inversely proportional to (XMn)2; [Mn] to XCo(XNi); and [Co] to XCo. The relationships between metal concentrations and stoichiometry may indicate that nickel, as a next-nearest neighbor on the positive electrode surface, can make dissolution more favorable in some instances.