Lattice Engineering on Li 2 CO 3 -Based Sacrificial Cathode Prelithiation Agent for Improving the Energy Density of Li-Ion Battery Full-Cell.

Developing sacrificial cathode prelithiation technology to compensate for active lithium loss is vital for improving the energy density of lithium-ion battery full-cells. Li 2 CO 3 owns high theoretical specific capacity, superior air stability, but poor conductivity as an insulator, acting as a promising but challenging prelithiation agent candidate. Herein, extracting a trace amount of Co from LiCoO 2 (LCO), a lattice engineering is developed through substituting Li sites with Co and inducing Li defects to obtain a composite structure consisting of (Li 0.906 Co 0.043 ▫ 0.051 ) 2 CO 2.934 and ball milled LiCoO 2 (Co-Li 2 CO 3 @LCO). Notably, both the bandgap and Li─O bond strength have essentially declined in this structure. Benefiting from the synergistic effect of Li defects and bulk phase catalytic regulation of Co, the potential of Li 2 CO 3 deep decomposition significantly decreases from typical >4.7 to ≈4.25 V versus Li/Li + , presenting >600 mAh g -1 compensation capacity. Impressively, coupling 5 wt% Co-Li 2 CO 3 @LCO within NCM-811 cathode, 235 Wh kg -1 pouch-type full-cell is achieved, performing 88% capacity retention after 1000 cycles.