摘要
开发高性能固态聚合物电解质是高安全、高比能固态锂金属电池的关键.然而,固态聚合物电解质的低离子电导率和不稳定的电解质/电极界面阻碍了其广泛应用.针对上述关键问题,本文基于聚环氧乙烷(PEO)基电解质,引入具有双功能的氟化铝(AlF_(3))做为添加剂,以提高复合电解质的离子电导率和界面稳定性.一方面,AlF_(3)做为一种强路易斯酸,在和锂盐阴离子相互作用下可以促进锂盐的解离,同时可以固定阴离子,从而提高锂离子传输效率;另一方面,AlF3在电解质/电极界面可以和锂金属原位反应生成富含LiF的界面层,从而抑制锂金属的不均匀沉积以及与PEO基体之间持续的副反应.得益于我们的合理设计,匹配改性后电解质的Li/Li对称电池可以稳定循环3600 h以上.同时,在2.4-4.2 V电压区间内,匹配复合电解质的全固态LiFePO4全电池在150个循环之后库伦效率比没有AlF3添加剂PEO基电解质大大提升(98.4%vs.63.3%),匹配复合固态电解质的固态锂金属电池显示出优异的界面稳定性和循环稳定性.
The development of high-performance solid polymer electrolytes is crucial for producing all-solid-state lithium metal batteries with high safety and high energy density.However,the low ionic conductivity of solid polymer electrolytes and their unstable electrolyte/electrode interfaces have hindered their widespread utilization.To address these critical challenges,a strong Lewis acid(aluminum fluoride(AIF_(3)))with dual functionality is introduced into poly(ethylene oxide)(PEO)-based polymer electrolyte.The AlF;facilitates the dissociation of lithium salt,increasing the iontransfer efficiency due to the Lewis acid-base interaction;further the in-situ formation of lithium fluoride-rich interfacial layer is promoted,which suppresses the uneven lithium deposition and continuous undesired reactions between the Li metal and PEO matrix.Benefiting from our rational design,the symmetric Li/Li battery with the modified electrolyte exhibits much longer cycling stability(over 3600 h)than that of the pure PEO/lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)electrolyte(550 h).Furthermore,the all-solid-state LiFeP04 full cell with the composite electrolyte displays a much higher Coulombic efficiency(98.4%after 150 cycles)than that of the electrolyte without the AlF;additive(63.3%after 150 cycles)at a large voltage window of 2.4-4.2 V,demonstrating the improved interface and cycling stability of solid polymer lithium metal batteries.
作者
王立通
仲云雷
文钊锐
李朝威
赵景新
葛明政
周鹏飞
张焱焱
汤育欣
洪果
Litong Wang;Yunlei Zhong;Zhaorui Wen;Chaowei Li;Jingxin Zhao;Mingzheng Ge;Pengfei Zhou;Yanyan Zhang;Yuxin Tang;Guo Hong(Institute of Applied Physics and Materials Engineering,University of Macao,Avenida da Universidade,Taipa,Macao SAR 999078,China;College of Chemical Engineering,Fuzhou University,Fuzhou 350116,China;Department of Physics and Chemistry,Faculty of Science and Technology,University of Macao,Avenida da Universidade,Taipa,Macao SAR 999078,China;School of Textile and Clothing,Nantong University,Nantong 226019,China)
基金
supported by the research fund of Shenzhen Science and Technology Innovation Committee(SGDX20201103093600003)
the University of Macao,Macao SAR(MYRG2018-00079-IAPME and MYRG2019-00115-IAPME)
the Science and Technology Development Fund,Macao SAR(0092/2019/A2,0059/2018/A2,and 009/2017/AMJ)
the National Thousand Young Talent plan
the National Natural Science Foundation of China(21875040&21905051)。
