Advanced Balancing of High-Energy Lithium Ion Cells Comprising Lithium-Rich Layered Oxide and a-Si/CuSi Nanowire Using a Cathode Pre-Lithiation Additive

Abstract Advances in lithium-ion battery (LIB) research have strived for high-energy, safe, and sustainable materials. Li-rich Li1.2Ni0.2Mn0.6O2 (LRNM) cathodes have shown great promise with high voltages and excellent specific capacities. Obstacles preventing the viability and commercialization of LRNM are the initial capacity loss of roughly 30% and rapid voltage decay upon cycling. Herein, lithium oxalate (Li2C2O4) is investigated as a pre-lithiation additive to utilize the first-cycle lithium re-intercalation losses of LRNM to compensate the irreversible lithium consumption in graphite and high-capacity a-Si on copper silicide nanowire (a-Si/CuSi NW) anodes. Specifically, the decomposition process of Li2C2O4 as well as the interaction between the electrode components inside the cell are comprehensively examined. This concept allows us to extend the cycle life of graphite||LRNM cells at 1C from less than 500 cycles (142 mAh g-1, 78%) to more than 900 cycles (143 mAh g-1, 82%) before reaching the 80% capacity retention threshold. Finally, LRNM electrodes with a precisely balanced concentration of Li2C2O4 are prepared in order to compensate the high irreversible losses of a-Si/CuSi NW anodes, achieving a capacity retention of almost 50% with a remaining specific capacity of 82 mAh g-1 after 400 cycles in high-energy a-Si/CuSi NW||LRNM lithium-ion cells.