硅烷基改性醚类电解质赋能高比能LiCoO_(2) ‖锂金属电池

Siloxane-modified ether based electrolyte boosting high-energy-density LiCoO_(2)‖Li battery

为改善醚类电解质和高压正极之间的界面兼容性,将锂电池的能量密度提升至350 W·h·kg^(-1)以上,本研究设计合成一种新型含硅烷基团的醚类电解质(Si-PEO),组装扣式电池,进行电化学性能和微观组织形貌分析。研究结果表明,该电解质中的醚链段用来解离锂盐和传导Li^(+),硅烷链段可以改善电解质的氧化稳定性,使其在室温下具有1.25×10^(-5) S·cm^(-1)的离子电导率和较高的电化学窗口(4.46 V)。LiCoO_(2)|Si-PEO|Li电池在室温下以0.5 C的倍率循环100圈后仍能保持160.12 mA·h·g^(-1)的放电比容量,容量保持率高达96.45%。循环后LiCoO_(2)正极颗粒完整,无副反应产物堆积,表面生成一层均匀且富含无机成分的正极/电解质界面。此界面层可以使Si-PEO电解质和正极有着优异的热兼容性,改善了LiCoO_(2)‖Li电池的安全性能。

To improve the interface compatibility between ether based electrolytes and high voltage cathodes,and increase the energy density to more than 350 W·h·kg^(-1) of lithium batteries,this study designed and synthesized an innovative ether-based electrolyte(Si-PEO)incorporating silane groups.Coin-type batteries were assembled for electrochemical performance and microstructure morphology analysis.The results show that ether chains are used to conduct lithium ions,and the silane chains contribute to improve the oxidative stability,which make the electrolyte have an ionic conductivity of 1.25×10^(-5) S·cm^(-1) at room temperature and a high electrochemical window(4.46 V).LiCoO_(2)|Si-PEO|Li batteries maintain a discharge specific capacity of 160.12 mA·h·g^(-1) and a high capacity retention of 96.45%at 0.5 C at room temperature after 100 cycles.On the cycled LiCoO_(2) cathode surface,the particles are intact,with no accumulation of side reaction products,and a uniform cathode electrolyte interphase rich in inorganic components has been generated.The interphase can enable Si-PEO electrolyte and the cathode to have excellent thermal compatibility,thus improving the safety performance of LiCoO_(2)‖Li batteries.