香港理工大学张标团队报道了非氟化醚降低高压NCM811-Li电池电极表面反应性。相关研究成果于2024年4月16日发表在国际顶尖学术期刊《德国应用化学》。

具有富镍（Ni）层状氧化物阴极的锂（Li）金属电池（LMBs）的能量密度是传统锂离子电池的两倍。然而，它们的寿命受到由高电极反应性引起的严重副反应的限制。氟化溶剂基电解质可以应对这一挑战，但它们会对环境和生物造成危害。

该项工作报道了无氟醚的分子工程，以减轻高压富镍LMBs中电极表面的反应性。通过仅延伸传统醚的烷基链，研究人员有效地降低了阴极在高压下对电解质的催化反应性，并抑制了电解质的氧化分解、阴极中的微观结构缺陷和岩盐相形成以及气体释放问题。高电压富镍NCM811锂电池在250次循环后可保持80%的容量，库伦效率高达99.85%，甚至优于碳酸盐电解质。

此外，该策略通过形成坚固的固体电解质界面促进了锂阳极的钝化，将锂的可逆性提高到99.11%，循环寿命为350次，优于传统的无氟醚电解质。因此，与传统的碳酸酯基和醚基电解质相比，实际LMBs的寿命分别延长了100%和500%以上。

附：英文原文

Title: Non-Fluorinated Ethers to Mitigate Electrode Surface Reactivity in High-Voltage NCM811-Li Batteries

Author: Zhijie Wang, Xiangli Che, Danni Wang, Yanyan Wang, Xiaomei He, Ye Zhu, Biao Zhang

Issue&Volume: 2024-04-16

Abstract: Lithium (Li) metal batteries (LMBs) with nickel (Ni)-rich layered oxide cathodes exhibit twice the energy density of conventional Li-ion batteries. However, their lifespan is limited by severe side reactions caused by high electrode reactivity. Fluorinated solvent-based electrolytes can address this challenge, but they pose environmental and biological hazards. This work reports on the molecular engineering of fluorine (F)-free ethers to mitigate electrode surface reactivity in high-voltage Ni-rich LMBs. By merely extending the alkyl chains of traditional ethers, we effectively reduce the catalytic reactivity of the cathode towards the electrolyte at high voltages, which suppresses the oxidation decomposition of the electrolyte, microstructural defects and rock-salt phase formation in the cathode, and gas release issues. The high-voltage Ni-rich NCM811-Li battery delivers capacity retention of 80% after 250 cycles with a high Coulombic efficiency of 99.85%, even superior to that in carbonate electrolytes. Additionally, this strategy facilitates passivation of the Li anode by forming a robust solid-electrolyte interphase, boosting the Li reversibility to 99.11% with a cycling life of 350 cycles, which outperforms conventional F-free ether electrolytes. Consequently, the lifespan of practical LMBs has been prolonged by over 100% and 500% compared to those in conventional carbonate- and ether-based electrolytes, respectively.

DOI: 10.1002/anie.202404109

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202404109