Lithium-Sulfur (Selenium) Batteries: Interface Issues and Solving Strategies

由于硫（硒）的导电性差、多硫（硒）化物的溶解、硫（硒）的体积膨胀、锂枝晶等问题，导致构建稳定的界面成为锂硫（硒）电池面临的重大挑战. 本文介绍了锂硫（硒）电池的研究进展，并以本课题组的研究工作为主，着重讨论了纳米限域效应、化学成键、界面吸附、表面包覆、电解液优化、负极改进等技术方案在锂硫（硒）电池中构建稳定界面的可行性.The stable interface is still a challenge for lithium-sulfur (selenium) batteries because of the low conductivity of sulfur (selenium), dissolution of polysulfide (polyselenide), volume expansion of sulfur (selenium), and lithium dendrite growth. This review describers some recent developments in lithium-sulfur (selenium) batteries and highlights our efforts in this field. The possible strategies for building stable interface in the lithium-sulfur (selenium) batteries including nano-restriction effect, chemical bonding, interface adsorption, surface coating, electrolyte optimization, and Lithium anode treatment have been discussed.国家自然科学基金项目（51225204, U1301244），国家重点研发计划项目（2016YFB0100100），中国科学院先导项目（XDA09010300）资助作者联系地址：中国科学院分子纳米结构与纳米技术重点实验室，中国科学院化学研究所，北京 100190Author's Address: CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Science, Beijing 100190, China通讯作者E-mail：[email protected]

Synthesis and Electrochemical Properties of LiFeSO4F/graphene Composite as Cathode Material for Lithium-ion Batteries

分别以FeSO4?H2O、FeSO4?4H2O和FeSO4?7H2O为原料与LiF在四甘醇介质中反应制得LiFeSO4F，用X射线衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）表征LiFeSO4F的结构和形貌．热重分析表明LiFeSO4F在400 °C开始分解．XRD结果表明，以FeSO4?4H2O和FeSO4?7H2O为原料，多个结晶水的存在可以延缓原料的脱水过程，有利于消除产物中FeSO4杂相的生成．利用循环伏安（CV）、电化学交流阻抗（EIS）和充放电实验测试了材料的电化学性能，发现加入石墨烯后可以促进LiFeSO4F的电化学活性，提高材料的比容量、倍率性能和循环性能．The LiFeSO4F was successfully synthesized from the reactions of FeSO4?xH2O (x=1, 4, 7) with LiF in tetraethylene glycol media through a facile low temperature method. The structures and microscopic features of the products were characterized by XRD, SEM and TEM. TGA result shows the good thermal stability of the as-prepared LiFeSO4F. No diffraction peaks of the FeSO4 are observed in the as-prepared products with the starting material of either FeSO4?4H2O or FeSO4?7H2O, which should be ascribed to delaying the release of H2O from the hydrated compounds. Cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS) results prove that the LiFeSO4F/graphene composite exhibit less electrochemical polarization and smaller impedance than those of pure LiFeSO4F, in which the graphene serves as the electronic conductivity support to enhance the lithium storage properties. The LiFeSO4F/graphene composite shows a high specific capacity, good rate capability and cycling stability compared with the pure LiFeSO4F.国家自然科学基金项目(No. 91127044，No. 20821003)；国家重大科学研究计划项目(No. 2011CB935700，No. 2009CB930400)资助作者联系地址：中国科学院化学研究所，分子纳米结构与纳米技术院重点实验室，北京 100190Author's Address: CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences CAS, Beijing, 100190, China通讯作者E-mail：[email protected]