(Invited) Characterization of Graphite Anode Architectures for Extreme Fast Charge Using Rapid EIS and Differential Coulometry

Abstract

The ability to fast charge automotive lithium-ion batteries is key to enabling wide-scale adoption by consumers. A primary challenge to fast charging is lithium plating due to insufficient lithium diffusion rates into the graphite anode. Plating and subsequent poor cycling of plated lithium leads to capacity loss over time and possible failure due to dendrite-induced short circuit. Sandia National Laboratories and the University of Michigan have worked together to develop advanced anode architectures, known as Highly Ordered Laser Electrode (HOLE), to increase lithium diffusion rates and avoid lithium plating. This work will describe Sandia's latest efforts to characterize and quantify the improvements brought on by these advanced anode structures. High precision cycling, rapid EIS, and isothermal control during fast charging allow precise tracking of cycle-to-cycle efficiency and intra-cycle differential coulometry. These methods are used to detect and quantify lithium plating at the earliest stages and provide a quantitative basis for evaluating lithium plating dependence on anode architecture, temperature, and current. A thorough discussion of experimental conditions will also be conducted to aid others in performing similar measurements. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.