Abstract: The greenhouse effect is aggravated by CO_2 generated by large-scale combustion of fossil fuels.Calcium cycle technology can not only achieve low-cost CO_2 capture,but also is one of the important methods of the thermochemical energy storage( TCES).In order to cope with the global warming problem,the renewable energy is large-scale developed and utilized,and the solar energy has broad prospects of large-scale industrial applications.However,the solar radiation is intermittent,the thermochemical energy storage technology emerges as the times require.The auxiliary CO_2 capture system of Ca O energy storage at coal-fired power stations and the high-temperature energy storage technology based on calcium cycle at solar thermal power stations were introduced. The influence factors including calcination conditions and particle sizes of materials on the cyclic energy storage performance of Ca O-based materials were analyzed.In addition,different methods of the improvement of the heat storage performance of Ca O-based materials were reviewed: the Ca O/Al_2O_3、Ca O/MgO、Ca O/SiO_2 composite energy storage materials are prepared by mechanical blending or chemical combustion synthesis.The results show that the Ca O energy storage system at coal-fired power station can improve power generation efficiency,reduce consumption of coal,and achieve emission reduction of CO_2.The energy storage density of Ca O/Ca CO_3 high temperature thermochemical system is as high as 3.2 GJ/m~3,which has high stability of energy storage cycle and can realize long-term energy storage without heat loss. The addition of inert carrier( Al_2O_3,MgO,SiO_2) can improve the activity and stability of Ca O heat cycle storage performance.The TCES based on carbonation/calcination reaction( calcium cycle) of Ca O-based materials at high temperature has great application prospects.In addition,the existing problems and research difficulties of Ca O-based energy storage materials were analyzed,and the research direction of energy storage was prospected. At present,the cycle activity of Ca O-based energy storage materials is reduced,and there is still a certain gap between the high-efficiency energy storage devices and practical applications. The preparation of the Ca O-based energy storage materials should be developed towards high energy storage density and high cycle activity.The improvement of overall power generation efficiency is the key to the optimization of energy storage systems.