Fast Charging of Lithium-ion Batteries via Electrode Engineering

Abstract

Vehicular electrification necessitates the need for fast charge of lithium-ion batteries (LIBs) involving high current densities such that the charging durations reach equivalence with internal combustion engine vehicles refueling times. High C-rate performance of LIBs requires overcoming challenges associated with Li plating, thermal excursions and battery shutdown at sub-zero temperatures. In this work, we aim to understand/improve fast charge characteristics by delving into the electrode level microstructural impact on battery performance in terms of delivered capacity, temperature rise and plating propensity. A microstructure-aware physics-based electrochemical-thermal model is used to ascertain the performance-safety indicators from sub-zero to standard thermal environments. Fast charge is an anode-centric phenomenon; consequently, optimal anode porosities and operating conditions are ascertained. At sub-zero temperatures, high C-rate operation up to a threshold provides good capacities and low plating propensity through large heat generation induced cell temperature elevation to appreciable levels. Beyond the threshold current, self-shutdown of the cell prevents any degradation. Additionally, standard thermal environment operation is majorly limited by rapid temperature rise beyond safe limits and large plating propensities at low porosities.