Enhancing Li⁺ Transport in NMC811||Graphite Lithium‐Ion Batteries at Low Temperatures by Using Low‐Polarity‐Solvent Electrolytes

Abstract

Abstract LiNi x Co y Mn z O 2 ( x +y+ z =1)||graphite lithium‐ion battery (LIB) chemistry promises practical applications. However, its low‐temperature (≤ −20 °C) performance is poor because the increased resistance encountered by Li + transport in and across the bulk electrolytes and the electrolyte/electrode interphases induces capacity loss and battery failures. Though tremendous efforts have been made, there is still no effective way to reduce the charge transfer resistance ( R ct ) which dominates low‐temperature LIBs performance. Herein, we propose a strategy of using low‐polarity‐solvent electrolytes which have weak interactions between the solvents and the Li + to reduce R ct , achieving facile Li + transport at sub‐zero temperatures. The exemplary electrolyte enables LiNi 0.8 Mn 0.1 Co 0.1 O 2 ||graphite cells to deliver a capacity of ≈113 mAh g −1 (98 % full‐cell capacity) at 25 °C and to remain 82 % of their room‐temperature capacity at −20 °C without lithium plating at 1/3C. They also retain 84 % of their capacity at −30 °C and 78 % of their capacity at −40 °C and show stable cycling at 50 °C.