清华大学深圳研究院Feiyu Kang研究团队取得一项新突破。他们在复合电解液的弱相互作用环境中实现了超长循环高压固态锂电池。该研究于2024年4月1日发表于国际一流学术期刊《美国化学会杂志》上。

据介绍，聚偏氟乙烯(PVDF)基固体电解质具有锂盐-聚合物-少量残留溶剂的结构，是固态电池有前途的候选者。

在该研究中，研究人员在原子水平上阐明了聚偏氟乙烯(PVDF)基复合电解质的微观结构，并证明了Li⁺相互作用环境决定了界面稳定性和离子传输能力。聚合物作为“固体稀释剂”和填料，实现了溶剂均匀分布。研究人员提出了一种构建弱相互作用环境的通用策略，即用设计的2,2,2-三氟乙酰胺(TFA)取代传统的N,N-二甲基甲酰胺(DMF)溶剂。

TFA较低的Li⁺结合能形成丰富的团聚体，形成富无机界面相，实现界面相容性。由于TFA与PVDF和填料的相互作用较弱，电解质的离子电导率达到7.0 × 10^-4 S cm^-1。固态Li||LiNi_0.8Co_0.1Mn_0.1O₂电池分别在4.3 V和4.5 V的截止电压下稳定循环4900次和3000次，并且在-20至45°C下具有优异的稳定性和300 Wh kg^-1的高能量密度。

附 ：英文原文

Title: Weak-Interaction Environment in a Composite Electrolyte Enabling Ultralong-Cycling High-Voltage Solid-State Lithium Batteries

Author: Ke Yang, Jiabin Ma, Yuhang Li, Junyu Jiao, Shizhe Jiao, Xufei An, Guiming Zhong, Likun Chen, Yuyuan Jiang, Yang Liu, Danfeng Zhang, Jinshuo Mi, Jie Biao, Boyu Li, Xing Cheng, Shaoke Guo, Yuetao Ma, Wei Hu, Shichao Wu, Jiaxin Zheng, Ming Liu, Yan-Bing He, Feiyu Kang

Issue&Volume: April 1, 2024

Abstract: Poly(vinylidene fluoride) (PVDF)-based solid electrolytes with a Li salt-polymer-little residual solvent configuration are promising candidates for solid-state batteries. Herein, we clarify the microstructure of PVDF-based composite electrolyte at the atomic level and demonstrate that the Li+-interaction environment determines both interfacial stability and ion-transport capability. The polymer works as a “solid diluent” and the filler realizes a uniform solvent distribution. We propose a universal strategy of constructing a weak-interaction environment by replacing the conventional N,N-dimethylformamide (DMF) solvent with the designed 2,2,2-trifluoroacetamide (TFA). The lower Li+ binding energy of TFA forms abundant aggregates to generate inorganic-rich interphases for interfacial compatibility. The weaker interactions of TFA with PVDF and filler achieve high ionic conductivity (7.0 × 10–4 S cm–1) of the electrolyte. The solid-state Li||LiNi0.8Co0.1Mn0.1O2 cells stably cycle 4900 and 3000 times with cutoff voltages of 4.3 and 4.5 V, respectively, as well as deliver superior stability at 20 to 45 °C and a high energy density of 300 Wh kg–1 in pouch cells.

DOI: 10.1021/jacs.4c00976

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c00976