Dual-Functional Cathodic Prelithiation Reagent of Li₃P in Lithium-Ion Battery for Compensating Initial Capacity Loss and Enhancing Safety

Prelithiation is an effective way to compensate the initial capacity loss (ICL) in lithium-ion batteries (LIBs), which is caused by the formation of solid electrolyte interface (SEI). In order to improve the overall energy capacity of a LIB, herein we propose the dual-functional cathodic prelithiation reagent of Li3P that can compensate initial capacity loss and enhance the security. With a high theoretical capacity of 1547.61 mA h g–1 and a relatively low lithiation potential, Li3P is able to sacrifice its Li+ during the first charging process. In a LiFePO4(LFP)//graphite full cell, the high initial charge capacity of 177.5 mA h g–1 can be achieved with 2.5% Li3P in the LFP side, and the discharge capacity is 160.6 mA h g–1 (10.2% higher than the pristine LFP). Furthermore, phosphorus that was left on the cathode after the Li extraction of Li3P can act as a fire retardant to improve the safety of the cell.