Li₂CO₃ Nanocomposites as Cathode Lithium Replenishment Material for High-Energy-Density Li-Ion Batteries

The irreversible capacity loss of lithium-ion batteries during initial cycling directly leads to a decrease in energy density, and promising lithium cathode replenishment can significantly alleviate this problem. In response to the problems of complex preparation, instability in air, and unfavorable residue of the conventional cathode lithium replenishment materials, a Li₂CO₃/carbon nanocomposite is prepared and utilized as the lithium replenishment material. With high-speed ball-milling, a nanocomposite with a tight embedment structured Li₂CO₃/Ketjen Black (KB) composite composed of nanosized Li₂CO₃ and KB is synthesized. The decomposition potential of Li₂CO₃ is effectively decreased to 3.8 V, and the amount of the active lithium ion being released is significantly increased, corresponding to a specific capacity of 645.2 mAh·g^-1 during the initial charging cycle. It has been introduced into the full-cells composed of the NCM523 cathode and graphite anode, resulting in a capacity increase of 44 mAh·g^-1 in the initial cycle and a 26.4% improvement in capacity retention over 100 cycles. The working mechanism of the Li₂CO₃/KB nanocomposite as the lithium replenishment agent has been discussed. The outcome of the work provides a practically feasible route to realize lithium-ion battery technology with improved energy density and cycling life.