From −20 °C to 150 °C: a lithium secondary battery with a wide temperature window obtained via manipulated competitive decomposition in electrolyte solution

Abstract

Lithium secondary batteries (LSBs) have witnessed explosive growth in the last decade. A wide operating temperature window is crucial for practical applications. A new concept is developed to expand the temperature window between −20 °C and 150 °C, where a competitive decomposition process between the electrolyte and solvent is manipulated with adiponitrile (ADN) over a wide temperature range. The decomposition of ethylene carbonate (EC) solvent and anions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium oxalyldifluoroborate (LiODFB) is regulated with ADN via a temperature-dependent lithium solvation mechanism. As a result, a SEI layer with a rich inorganic component is formed at elevated temperatures, leading to improved performance in lithium titanate (LTO)/Li, lithium iron phosphate (LFP)/Li, and LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523)/Li batteries over a wide temperature range. It enables a coulombic efficiency (CE) of 97.39% at 100 °C and more than 100 hours of cycling of Li/Li batteries at 150 °C, as well as stable cycling of LFP/Li batteries in the temperature range between 120 °C and −20 °C. Stable cycling performance is demonstrated with the LTO/Li batteries over a wider temperature range from −40 °C to 150 °C. High-temperature electrochemical stability is exhibited at 5C, with a capacity retention ratio of 87.94% at 120 °C and 99.93% at 100 °C after 1000 cycles.