College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China.
College of Chemical Engineering and Safety, Binzhou University, Binzhou, Shandong 256603, P. R. China.
ACS Appl Mater Interfaces. 2023 Mar 8;15(9):11777-11786. doi: 10.1021/acsami.2c22089. Epub 2023 Feb 21.
Li-metal batteries (LMBs), especially in combination with high-energy-density Ni-rich materials, exhibit great potential for next-generation rechargeable Li batteries. Nevertheless, poor cathode-/anode-electrolyte interfaces (CEI/SEI) and hydrofluoric acid (HF) attack pose a threat to the electrochemical and safety performances of LMBs due to aggressive chemical and electrochemical reactivities of high-Ni materials, metallic Li, and carbonate-based electrolytes with the LiPF salt. Herein, the carbonate electrolyte based on LiPF is formulated by a multifunctional electrolyte additive pentafluorophenyl trifluoroacetate (PFTF) to adapt the Li/LiNiCoMnO (NCM811) battery. It is theoretically illustrated and experimentally revealed that HF elimination and the LiF-rich CEI/SEI films are successfully achieved via the chemical and electrochemical reactions of the PFTF additive. Significantly, the LiF-rich SEI film with high electrochemical kinetics facilitates Li homogeneous deposition and prevents dendritic Li from forming and growing. Benefiting from the collaborative protection of PFTF on the interfacial modification and HF capture, the capacity ratio of the Li/NCM811 battery is boosted by 22.4%, and the cycling stability of the symmetrical Li cell is expanded over 500 h. This provided strategy is conducive to the achievement of high-performance LMBs with Ni-rich materials by optimizing the electrolyte formula.
锂金属电池（LMBs），特别是与高能量密度富镍材料相结合，在下一代可充电锂电池方面显示出巨大的潜力。然而，由于高镍材料、金属锂和碳酸酯基电解质与 LiPF 盐具有很强的化学和电化学反应性，较差的正极/负极-电解质界面（CEI/SEI）和氢氟酸（HF）攻击对 LMBs 的电化学和安全性能构成了威胁。在此，基于 LiPF 的碳酸酯电解质通过多功能电解质添加剂五氟苯基三氟乙酸酯（PFTF）来适应 Li/LiNiCoMnO（NCM811）电池。理论上说明了并通过 PFTF 添加剂的化学和电化学反应实验证明了 HF 的消除和富 LiF 的 CEI/SEI 膜的成功实现。值得注意的是，具有高电化学动力学的富 LiF 的 SEI 膜有利于 Li 的均匀沉积，并防止枝晶 Li 的形成和生长。得益于 PFTF 在界面改性和 HF 捕获方面的协同保护，Li/NCM811 电池的容量比提高了 22.4%，对称 Li 电池的循环稳定性扩展到 500 小时以上。这种优化电解质配方的策略有利于实现具有富镍材料的高性能 LMBs。
