A porous current collector cleaner enables thin cathode electrolyte interphase on LiCoO2 for stable high-voltage cycling

Abstract

LiCoO₂ (LCO) is the most successful commercial cathode for lithium-ion batteries due to its high theoretical specific capacity (274 mA h g⁻¹). However, LCO-based batteries show a significantly high degree of instability in cycling performance and severe capacity fading as voltages exceed 4.35 V versus Li/Li⁺. Herein, a carbon nanotube macrofilm (CMF) was used as a current collector for addressing the long-standing issues, which demonstrate LCO with the first specific capacities of 191.1 and 180.1 mA h g⁻¹ after 300 cycles, at 4.5 V. The excellent results are ascribed to the interactions between decomposed electrolytes and carbon nanotubes, which ensure that decomposition products around the cathode are cleaned timely by the current collector cleaner. Therefore an ultrathin cathode electrolyte interphase is obtained and keeps the feature in the subsequent cycles. The assembled LCO-based pouch cell also indicates a high energy density of 523 W h kg⁻¹ after 200 cycles. This work presents novel insights into cathodes with stable cycling at high voltages.