Demarcating the Impact of Electrolytes on High‐Nickel Cathodes and Lithium‐Metal Anode

Abstract

AbstractThe ever‐growing demand for low‐cost, high‐energy‐density lithium‐ion batteries (LIBs) makes high‐nickel layered oxide cathodes, especially LiNiO2 (LNO), one of the most appealing candidates. However, poor structural and surface instability that leads to a short cycle life remains a formidable challenge. Herein, a systematic investigation of LNO performance in two different electrolytes (a conventional carbonate‐based LP57 electrolyte and an ether‐based localized high‐concentration electrolyte (LHCE)) with different charge cut‐off voltages is presented. These findings show that the cathode‐electrolyte reactivity is the main factor dictating the performance degradation of LNO at high voltages rather than bulk integrity. While LHCE can provide good stability beyond 4.2 V with a robust, uniform solid–electrolyte interphase (SEI) layer on the Li‐metal anode, there is no significant difference in cyclability at 4.15 V (96% capacity retention after 200 cycles) for both LP57 and LHCE. From LNO symmetric cells, carbonate‐based electrolyte is found to be good for LNO stability while ether‐based electrolyte is beneficial toward Li‐metal anode. Thus, a suitable electrolyte or a low cut‐off voltage is necessary to maintain a decent cycle life. Altogether, this work highlights the impact of electrolyte and cut‐off voltage on LNO and Li‐metal, which can help guide the development of cells based on LNO.