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

Abstract

The 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.

Comparative Study of Lithium-Rich Cathode in Ester- and Ether-Based Localized High-Concentration Electrolytes

“…The C–C, C–O, CH 2 –CF 2 , CO, and C–F peaks are contributed by PVDF, Super-P, and the decomposition of electrolyte. The CO (∼532.5 eV) and C–O/S-O/N–O (∼533.4 eV) peaks from the cathode of DME-LHCE are significantly enhanced compared to that of the DMC-LHCE, , and no M–O (∼530.2 eV) peak is observed in the DME-LHCE, suggesting a substantial accumulation of decomposition products on cathode surface. Furthermore, the enhanced peaks of C–SO x 2– and S n 2– in the S 2p spectra further substantiate the increased extent of oxidation from the DME-LHCE.…”

Understanding the Effects of Al and Mn Doping on the H2–H3 Phase Transition in High-Nickel Layered Oxide Cathodes

“…During the H2–H3 transition, however, the trend is reversed with an abrupt reduction in the CALP . This H2–H3 phase transition has been associated with several deleterious effects, including particle cracking, increased off-gassing, and transition metal dissolution. , In several cases, researchers and companies alike have opted to avoid the H2–H3 phase transition entirely for improved cycle life at the expense of accessible capacity. − Notably, the H2–H3 transition region accounts for ∼20% of the specific capacity in a high-nickel layered oxide cathode, when it is cycled to 4.4 V . Thus, there is an unavoidable trade-off between capacity retention and accessible capacity for high-nickel cathode materials.…”

Understanding the Effects of Bi Modification on the Properties of Ni‐Rich Cathodes

“…[3][4][5] However, these cathode materials often face fading issues, like structure degradation. [6][7][8] The structure degradation is mainly caused by the structure collapse and the irreversible phase transition during lithiation/delithiation process, leading to fast capacity fading. [9][10][11] Meanwhile, the poor stability of structure can also cause low capacity at high rates.…”