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.