Fast Charging of Lithium-ion Batteries via Electrode Engineering

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. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.