Special report on the achievements realized by researchers of Chinese Academy of Sciences in the field of energy storage technologies

The inevitable depletion of non-renewable fossil fuels and serious environmental pollution promote the wide application of renewable energies. Most of the renewable energy sources, such as solar and wind power, suffer from uncontrollable as well as complicated situations (Yang et al., 2011) [1]. Electrochemical energy storage technologies are crucial to solve these problems, as they can efficiently store electricity in chemicals and release it according to the users' demands (Yang et al., 2011; He et al., 2006)[1], [2]. Moreover, energy and environmental challenges have stimulated great interest to replace gasoline engine powered vehicles by plug-in hybrid vehicles (PHEV) and electric vehicles (EVs). Therefore, it is vital to improve the performance of energy storage systems, which depends on the development of key materials for the various batteries and new energy storage strategies. Researchers from Chinese Academy of Science (CAS) have dedicated to the researches of energy storage systems for decades and made significant process. We will introduce the progress on energy storage systems of CAS in recent two years, which covers the key materials of Lithium ion battery (LIB), Lithium-oxygen (Li-O2) battery, Lithium-sulfur (Li-S) battery, Lithium ion capacitor, Sodium ion battery, and Flow battery.