It is also critical to avoid degradation (i.e., impedance growth or capacity loss) of the AM during high-current measurements, which can expose the AM surface to extreme voltages. Given the notorious surface instability of LCO, both the AM and electrolyte were optimized to reduce surface reactivity . The LCO is doped with 2% Al, 0.5% Ti, and 0.5% Mg to suppress deleterious phase transitions and oxygen loss at the surface . The electrolyte uses FEC and LiPO2F2 additives to form passivation layers on the LCO surface, while the LiTDI additive inhibits chemical degradation of the electrolyte and subsequent reaction of acidic species with the LCO surface . Without LiTDI, severe impedance growth occurs in LCO symmetric cells over a timescale of several hours, making it impossible to obtain accurate measurements (Fig. ).