Cobalt–Nickel Exchange in Exfoliated Battery Layered Cathode Sheets with Application to Recycling

Abstract

With the emerging dominance of electric vehicles (EV) in the transportation sector, recycling or upcycling spent battery materials will be required to reduce EV costs, lessen waste, and ease critical material supply chain issues for EV batteries. Motivated by work in the literature describing the exfoliation of layered oxides, first-principles calculations are performed to show that Li_xCoO₂, if exfoliated into nanosheets, can readily undergo transition metal cation exchange in aqueous media. The substitution of Co³⁺ or Co⁴⁺ cations inside the sheet by Ni²⁺ is associated with modest reaction barriers (ΔG* ≈ 0.3–0.7 eV) and is at most mildly endothermic (ΔG ≈ 0.2–0.3 eV). In contrast, previous battery degradation studies have shown that Co³⁺ diffusion is strongly inhibited inside bulk layered oxides. This suggests that processing spent layered oxides as nanosheets can provide a potentially low-energy-cost pathway to altering the transition metal and/or dopant stoichiometry, which can be used toward developing new room-temperature upcycling routes for cathodes from end-of-life batteries.