A Scalable and Controllable Li‐Powder‐Coating Prelithiation Method Toward Ultralong‐life and High‐Energy‐Density LiFePO4 Battery

Abstract

LiFePO4/graphite battery is considered to be the ideal Li‐ion battery for grid energy storage, which requires long cycle life. However, the formation of solid electrolyte interphase (SEI) in the first charge and discharge process and regeneration of SEI during cycling causes continuous loss of active lithium, which reduces the reversible capacity of the battery and shortens its cycle life. Prelithiation of the negative electrode is an effective method to supplement the loss of active lithium, thereby improving the cycle life and energy density of the battery. This work uses stable lithium powder, solid electrolyte (Li6.4La3Zr1.4Ta0.6O12), and polyvinylidene fluoride to prepare a stable prelithiation reagent, which is coated on the surface of a graphite electrode using a microgravure‐coating machine. The effects of the proposed prelithiation method on initial Coulombic efficiency, cycle life, and calendar life of batteries are investigated. It is found that this method can increase the cycle life of graphite/lithium iron phosphate pouch cells, with the initial Coulombic efficiency increased by 3.43%, and is readily applicable for industrial applications.