A lithium carbonate-based additive for the interfacial stabilization of LiCoO2 cathode at 4.6 V

Extending the charging voltage of LiCoO 2 (LCO) is an   ongoing and promising approach to increase its energy density. However, the main challenge of the approach lies in the insuperable cathodic interfacial processes at high voltage, which leads to rapid failure both in the performance and structure of the LCO cathode. Herein, a Li 2 CO 3 -based additive was prepared by a simple sand-milling method, enabling a low electrochemical decomposition voltage <4.6 V from commonly >4.8 V, stabilizing the interface of the LCO cathode at 4.6 V. The decomposition of Li 2 CO 3 provides extra Li + and CO 2 to supplement the Li consumption required in the initial irreversible interfacial reactions and rapidly form a uniform and stable cathode electrolyte interphase layer (less organic and more inorganic components) on the LCO cathode by reducing CO 2 . Thus, the phase transformation and the emergence of high-valent Co ions on the surface of LCO at 4.6 V high voltage were inhibited. Thanks to this, with 2% Li 2 CO 3 -based additive, the capacity retention of commercial LCO at a high voltage of 4.6 V at 0.5 C for 100 cycles was improved from 59.3% to 79.3%. This work improves the high-voltage stability of LCO and provides a new idea for realizing the high-voltage operation of batteries.