物理化学学报

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单离子聚合物快离子导体

薛国勇1,2, 李静2, 陈俊超3, 陈代前2, 胡晨吉2,3, 唐凌飞1,2, 陈博文1,2, 易若玮2, 沈炎宾1,2, 陈立桅2,3   

  1. 1 中国科学技术大学纳米技术与纳米仿生学院, 合肥 230026;
    2 中国科学院苏州纳米技术与纳米仿生研究所, 创新实验室卓越纳米科学中心, 江苏 苏州 215123;
    3 上海交通大学化学化工学院, 上海 200240
  • 收稿日期:2022-05-06 修回日期:2022-05-26 录用日期:2022-05-27 发布日期:2022-06-09
  • 通讯作者: 沈炎宾, 陈立桅 E-mail:ybshen2017@sinano.ac.cn;lwchen2018@sjtu.edu.cn
  • 基金资助:
    国家重点研究发展项目(2021YFB3800300)和国家自然科学基金(21733012, 22179143)资助

A Single-Ion Polymer Superionic Conductor

Guoyong Xue1,2, Jing Li2, Junchao Chen3, Daiqian Chen2, Chenji Hu2,3, Lingfei Tang1,2, Bowen Chen1,2, Ruowei Yi2, Yanbin Shen1,2, Liwei Chen2,3   

  1. 1 School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, China;
    2 i-Lab, CAS Center for Excellence in Nanoscience, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, Jiangsu Province, China;
    3 School of Chemistry and Chemical Engineering, Shanghai Jiaotong University, Shanghai 200240, China
  • Received:2022-05-06 Revised:2022-05-26 Accepted:2022-05-27 Published:2022-06-09
  • Contact: Yanbin Shen, Liwei Chen E-mail:ybshen2017@sinano.ac.cn;lwchen2018@sjtu.edu.cn
  • Supported by:
    This project was supported by the National Key Research and Development Program of China (2021YFB3800300) and the National Natural Science Foundation of China (21733012, 22179143).

摘要: 具有高锂离子迁移数和良好可加工性能的锂快离子导体对于全固态电池的发展非常重要。然而,现有的锂快离子导体主要限制于硬质陶瓷,目前尚无柔性聚合物类型的锂快离子导体被报道。在这个工作中,我们报告了一种通过三种不同有机单体的自由基聚合反应形成的三元无规共聚单离子快离子导体(SISC)。该SISC中包含丰富的锂离子传输位点和具有阴离子锚定功能的阴离子受体。此外,三种不同单体的共聚反应带来低结晶度和低玻璃化转变温度(Tg),有利于链段运动,从而获得小的锂离子传输的活化能(Ea)。电化学测试结果表明,该SISC的室温离子电导率和锂离子迁移数分别达到1.29 mS∙cm−1和0.94。将SISC与锂金属负极和多种正极(包括LiFePO4、LiCoO2和硫化聚丙烯腈(SPAN))原位聚合,组装得到的全固态电池具有良好的电化学稳定性。其中,Li||LiFePO4全固态电池表现出高达8C的倍率性能和良好的循环寿命(在0.5C倍率下稳定循环> 700圈)。这项工作提供了一种新颖的聚合物基快离子导体设计理念,对于发展高性能全固态电池具有重要意义。

关键词: 全固态锂金属电池, 聚合物固态电解质, 超离子导体, 单离子导体, 原位聚合, 倍率性能

Abstract: All-solid-state batteries (ASSBs) have been considered a promising candidate for the next-generation electrochemical energy storage because of their high theoretical energy density and inherent safety. Lithium superionic conductors with high lithium-ion transference number and good processability are imperative for the development of practical ASSBs. However, the lithium superionic conductors currently available are predominantly limited to hard ceramics. Practical lithium superionic conductors employing flexible polymers are yet to be realized. The rigid and brittle nature of inorganic ceramic electrolytes limits their application in high-performance ASSBs. In this study, we demonstrate a novel design of a ternary random copolymer single-ion superionic conductor (SISC) through the radical polymerization of three different organic monomers that uses an anion-trapping borate ester as a crosslinking agent to copolymerize with vinylene carbonate and methyl vinyl sulfone. The proposed SISC contains abundant solvation sites for lithium-ion transport and anion receptors to immobilize the corresponding anions. Furthermore, the copolymerization of the three different monomers results in a low crystallinity and low glass transition temperature, which facilitates superior chain segment motion and results in a small activation energy for lithium-ion transport. The ionic conductivity and lithium-ion transference number of the SISC are 1.29 mS·cm−1 and 0.94 at room temperature, respectively. The SISC exhibits versatile processability and favorable Young’s modulus (3.4 ± 0.4 GPa). The proposed SISC can be integrated into ASSBs through in situ polymerization, which facilitates the formation of suitable electrode/electrolyte contacts. Solid-state symmetric Li||Li cells employing in situ polymerized SISCs show excellent lithium stripping/plating reversibility for more than 1000 h at a current density of 0.25 mA·cm−2. This indicates that the interface between the SISC and lithium metal anode is electrochemically stable. The ASSBs that employ in situ polymerized SISCs coupled with a lithium metal anode and various cathodes, including LiFePO4, LiCoO2, and sulfurized polyacrylonitrile (SPAN), exhibit acceptable electrochemical stability, including high rate performance and good cyclability. In particular, the Li||LiFePO4 ASSBs retained ~ 70% of the discharge capacity when the charge/discharge rate was increased from 1 to 8C. They also demonstrate long-term cycling stability (> 700 cycles at 0.5C rate) at room temperature. A capacity retention of 90% was achieved even at a high rate of 2C after 300 cycles at room temperature. Furthermore, the SISCs have been applied to Li||LiFePO4 pouch cells and exhibit exceptional flexibility and safety. This work provides a novel design principle for the fabrication of polymer-based superionic conductors and is valuable for the development of practical ambient-temperature ASSBs.

Key words: All-solid-state lithium metal battery, Solid polymer electrolyte, Superionic conductor, Single-ion conductor, In situ polymerization, Rate performance

MSC2000: 

  • O647