Conformal Prelithiation Nanoshell on LiCoO2 Enabling High-Energy Lithium-Ion Batteries

The initial lithium loss in lithium-ion batteries (LIBs) reduces their energy density (e.g., 15% or higher for LIBs using a Si-based anode). Herein, we report in situ chemical formation of a conformal Li₂O/Co nanoshell (∼20 nm) on LiCoO₂ particles as a high-capacity built-in prelithiation reagent to compensate this initial lithium loss. We show a 15 mAh g^-1 increase in overall charge capacity for the LiCoO₂ with 1.5 wt % Li₂O/Co in comparison to the pristine LiCoO₂ in virtue of the irreversible lithium extraction from the nanoshell (4Li₂O + 3Co → 8Li⁺ + 8e^- + Co₃O₄, 2Li₂O → 4Li⁺ + 4e^- + O₂↑). Paired with a graphite-SiO anode, a full cell using such a LiCoO₂ cathode demonstrates 11% higher discharge capacity (2.60 mAh cm^-2) than that using pristine LiCoO₂ (2.34 mAh cm^-2) at 0.1 C, as well as stable battery cycling. Moreover, the prelithiated LiCoO₂ is compatible with the current battery fabrication process.