The development of high voltage electrolytes plays a critical role to achieve advanced lithium ion batteries with high energy density. Application of suitable electrolyte additives is a facile and effective way to achieve enhanced electrochemical performance at high voltage operation. In this work, 2-(trifluoroacetyl) thiophene (TFPN) was investigated as a functional electrolyte additive for high performance lithium ion batteries using high-voltage LiCoO₂ cathode. When cycled between 3.0 V and 4.4 V at 0.5 C, the capacity retention of the LiCoO₂ cathode significantly increases from 33.2 %–90.6 % by the addition of 0.5 wt% TFPN into the baseline electrolyte. Based on the measurements on impedance spectra and X-ray photoelectron spectra, the improved cycling performance is attributed to the preferential oxidation of TFPN on the cathode surface and thus form a protective layer to suppress the decomposition of both electrolyte solvent and lithium salt. This work presents that TFPN has great potential as functional additive for the development of high-voltage and high-energy-density lithium ion batteries.

高压电解质的开发对于实现具有高能量密度的高级锂离子电池起着至关重要的作用。合适的电解质添加剂的应用是在高压操作下实现增强的电化学性能的便捷有效方法。在这项工作中，研究了2-（三氟乙酰基）噻吩（TFPN）作为使用高压LiCoO ₂阴极的高性能锂离子电池的功能电解质添加剂。在0.5 C下在3.0 V至4.4 V之间循环时，LiCoO ₂的容量保持率通过在基线电解液中添加0.5 wt％TFPN，阴极显着增加，从33.2％至90.6％。基于对阻抗谱和X射线光电子谱的测量，改善的循环性能归因于TFPN在阴极表面上的优先氧化，因此形成了抑制电解质溶剂和锂盐分解的保护层。这项工作表明，TFPN作为开发高电压和高能量密度锂离子电池的功能添加剂具有巨大潜力。