Determining the oxidation states of dissolved transition metals in battery electrolytes from solution NMR spectra

Abstract

Dissolved transition metal ions can induce peak shifts in the NMR spectra of degraded battery electrolytes. Here, we exploit this staightforward, accessible method to calculate magnetic moments for dissolved Ni²⁺, Mn²⁺, Co²⁺, and Cu²⁺; subsequent analysis of dissolution from LiMn₂O₄, LiNiO₂, and LiNi_0.5Mn_1.5O₄ shows that the dissolved metals are exclusively divalent.