Enabling 4C Fast Charging of Lithium- Ion Batteries by Coating Graphite with a Solid- State Electrolyte

Abstract

Enabling fast- charging (- ¥4C) of lithium- ion batteries is an important challenge to accelerate the adoption of electric vehicles. However, the desire to maximize energy density has driven the use of increasingly thick electrodes, which hinders rate capability. Herein, atomic layer deposition is used to coat a single- ion conducting solid electrolyte (Li3BO3- Li2CO3) onto postcalendered graphite electrodes, forming an artificial solid- electrolyte interphase (SEI). When compared to uncoated control electrodes, the solid electrolyte coating: 1) eliminates natural SEI formation during preconditioning; 2) decreases interphase impedance by >75% compared to the natural SEI; and 3) extends cycle life under 4C charging conditions, enabling retention of 80% capacity after 500 cycles (compared to 12 cycles in the uncoated control) in pouch cells with >3 mAh cm- 2 loading. This work demonstrates that 4C charging without Li plating can be achieved through purely interfacial modification without sacrificing energy density and sheds new light on the role of the SEI in Li plating and fast- charge performance.An artificial solid- electrolyte interphase (SEI) coating with 75% lower impedance is demonstrated compared to the natural SEI. This coating enables stable cycling under 4C (15 min) charging conditions, retaining 80% capacity over 500 cycles. This challenges the prevailing assumption that mass transport limitations must be addressed to enable fast charging.