A low-cost inorganic oxide as dual-functional electrolyte additive towards long cycling Li-rich Mn-based cathode materials

Li-rich Mn-based cathode materials (LRM) have received great attention owing to their high capacity and low cost. However, the mismatch between the widely used carbonate electrolyte and the LRM cathode and lithium metal anode causes a series of problems, such as electrolyte continuous oxidation, cathode structure degradation, and Li dendritic growth. Herein, inorganic oxide B₂O₃ is introduced as a dual-functional high-voltage electrolyte additive to construct stable cathode electrolyte interphase and solid electrolyte interphase for Li||LRM batteries. The modified interface derived from the additive can induce dendrite-free Li deposition, stabilize cathode structure, and inhibit transition metal dissolution. Moreover, the adverse side reactions are mitigated, thus enhancing Li⁺ transport rate and reducing interface impedance. With the addition of B₂O₃ into the carbonate electrolyte, the Li||LRM battery exhibits an enhanced discharge capacity of 221 mAh g^-1 after 200 cycles, equaling a capacity retention of 92.1%. When the upper cut-off voltage is increased to 5 V, a superior capacity retention of > 85% can still be achieved after 150 cycles at 1 C. In addition, the low cost of B₂O₃ benefits for commercial application. This work offers new guidance for the research of low-cost, high-voltage dual-functional additives for advanced lithium metal batteries.