Competitive Coordination Effect to Simultaneously Achieve High-Energy and Stable Cycles in Li-Metal Pouch Cell under –40°C

Abstract

Lithium metal batteries (LMBs) are expected to have significant advantages under extreme low-temperature conditions (i.e., −40°C), mainly due to the much short ion transport pathway and deposition/stripping mechanism of Li metal anode. However, high-energy-density Li-metal pouch cells capable of stable operation at −40°C have rarely been reported due to the harsh condition under extremely low-temperature. Herein, a Li-metal pouch cell suitable for use at −40°C was designed, and coupled with a newly developed electrolyte, to simultaneously achieve high energy and stable cycling performance. The low-temperature capability of the LMBs is activated by a competitive coordination effect in the first solvation sheaths. The competitive coordination between Li+ and dimethyl carbonate (DMC) and 1, 2-dimethoxyethane (DME) weakens the interaction between Li+ and the solvent, widens the voltage window, and facilitates the formation of robust inorganic-rich interfaces under low-temperature conditions. Notably, a low-temperature Li-metal pouch cell was designed and assembled with an energy at 300 Wh kg−1. When tested at the extremely low temperature of −40°C, the Li-metal pouch cell can retain 77% of its energy output, with 93% capacity retention after 70 cycles. This work paves the way for low-temperature LMBs with competitive energy density and stable cycle life.