A Prelithiation Separator for Compensating the Initial Capacity Loss of Lithium-Ion Batteries.

Lithium loss during the initial charge process inevitably reduces the capacity and energy density of lithium-ion batteries. Cathode additives are favored with respect to their controllable prelithiation degree and scalable application; however, the insulating nature of their delithiation products retards electrode reaction kinetics in subsequent cycles. Herein, we propose a prelithiation separator by modifying a commercial separator with a Li2S/Co nanocomposite to compensate for the initial capacity loss. The Li2S/Co coating layer extracts active lithium ion during the charge process and shows a delithiation capacity of 993 mA h g-1. When paired with a LiFePO4|graphite full cell, the reversible capacity is increased from 112.6 to 150.3 mA h g-1, leading to a 29.5% boost in the energy density. The as-prepared pouch cell also demonstrates a stable cycling performance. The excellent electrochemical performance and the scalable production of the prelithiation separator reveal its great potential in lithium-ion battery industry application.