High-Capacity Li3P pre-lithiation agent unlocks superior performance in lithium-ion capacitors

Abstract

Pre-lithiation is a pivotal process for lithium-ion capacitors (LICs)/batteries, as it effectively regulates the anode potential and mitigates the irreversible lithium loss that occurs during the formation of the solid electrolyte interface (SEI). However, the scarcity of high-capacity pre-lithiation reagents and the lack of compatible processes have significantly impeded the large-scale production and broad application of LICs. In this study, we propose Li₃P as a high-capacity pre-lithiation reagent for LIC anodes. Li₃P was synthesized via a reaction between black phosphorus and molten lithium metal. Furthermore, a PTFE-binder-based dry-process method is developed for fabricating AC/Li₃P composite cathodes. This method overcomes the issue of Li₃P reactivity with conventional solvents typically used in wet coating processes and is fully compatible with the large-scale production of standard activated carbon (AC) electrodes. Li₃P irreversibly decomposes during the first charging cycle, achieving an actual specific capacity of 1078 mAh/g and thereby supplying a significant amount of Li₊. The LIC assembled with the Li₃P/AC cathode demonstrates enhanced specific capacity and long-term cyclic stability. The pre-lithiated LIC exhibits an outstanding energy density of 93.44 Wh/kg and power density of 12.52 kW/kg, surpassing conventional electrochemical pre-lithiated LICs and showing great potential for practical applications.