Enabling fast formation for lithium-ion batteries with a localized high-concentration electrolyte

Abstract

Formation cycling currently represents a severe bottleneck in the lithium-ion battery (LIB) manufacturing process. The low currents required to form a stable solid-electrolyte interphase (SEI) and avoid lithium plating lead to long formation times. Consequently, formation represents one of the most expensive and energy-intensive stages of LIB production, and one of the largest opportunities for reducing production costs. Herein, we investigate the impacts of increasing the formation rate on graphite anode with different electrolytes and electrode loading conditions. We find that although LIBs are tolerant of formation rates up to ∼1C at ∼2.2 mA h cm⁻² loading, lithium plating leads to severe loss of lithium inventory when the loading is increased to a practical value of ∼5.0 mA h cm⁻², leading to low specific capacity. However, by introducing a localized high-concentration electrolyte, this effect can be effectively mitigated, enabling a first-cycle duration of 2–3 h with minimal loss of capacity even at practical anode loading.