摘要
Rechargeable Li-CO2 batteries provide a promising new approach for carbon capture and energy storage technology. However, their practical application is limited by many challenges despite much progress in this technology. Recent development in Li-CO2 batteries is presented. The reaction mechanism with an air cathode, operating temperatures used, electrochemical performance under different CO2 concentrations, stability of the battery in different electrolytes, and utilization of different cathode materials were emphasized. At last, challenges and perspectives were also present- ed. This review provides a deep understanding of Li-CO2 batteries and offers important guidelines for developing reversible and high efficiency Li-CO2 batteries.
对化石能源依赖所造成的能源安全和环境污染等问题限制了人类社会的可持续发展.Li-CO_2电池能量密度高、原材料成本低廉且结构简单,因而被认为是开发和利用可再生清洁能源的有力技术,在住宅能量存储、电动汽车驱动和智能电网等领域具备良好的应用前景.此外,CO_2等温室气体的大量排放是全球变暖的主要原因,Li-CO_2电池放电时可将空气中的CO_2还原固定,生成的碳材料可用作燃料和化工原料,在资源利用化上提供了新途径.Li-CO_2电池是建立在锂-空气电池的基础上.相比大气中的其他成分,H2O与CO_2对该电池的影响很大.防水膜可以减少水的影响;而在放电过程中,CO_2的存在会生成Li_2CO_3,Li_2CO_3是可以分解的.由此可见,CO_2在可充放的锂电池中作为正极活性成分储能,从而被利用起来.目前Li-CO_2电池至少面临三个问题:(1)电池充放电的机理尚不完全清楚,并且以O2和CO_2混合气为活性气体的机理与以纯CO_2为活性气体的机理是有差别的,Li_2CO_3的生成与分解的机制仍在探索中;(2)电解液的稳定性;(3)寻找高效的正极催化剂材料.本文介绍了Li-CO_2电池的发展历程,讨论了Li-CO_2电池的充放电机理、电解液的影响以及正极催化材料的选取等.综述了活性气体为纯CO_2和CO_2-O2混合气时机理的差别,以及CO_2/O2混合比对电池性能的影响.选取电解液应考虑其粘度和介电性.高效能的正极催化材料大多具有高导电性、多孔结构和大的比表面积等特点.而温度也是影响Li-CO_2电池性能的因素之一.虽然Li-CO_2电池的概念相对较新,但可实现CO_2在能源储存与转化领域中的应用,并为Li-O2电池向锂空气电池飞跃提供了重要参考.本文以如何提高正极材料的催化性能和Li_2CO_3的生成和分解机理为重点,总结了正极材料所具有的导电性、比表面积、特殊结构等特点,以及相关机理.
基金
supported by the National Basic Research Program of China(973 Program,2014CB932302,2014CB932303)
the National Natural Science Foundation of China(21403107,21373111)
Natural Science Foundation of Jiangsu Province of China(BK20140055)
Specialized Research Fund for the Doctoral Program of Higher Education of China(20120091120022),PAPD of Jiangsu Higher Education Institutions
the Project on Union of Industry-Study-Research of Jiangsu Province(BY2015069-01)
