New electrochemical energy storage systems based on metallic lithium anode-the research status, problems and challenges of lithium-sulfur, lithium-oxygen and all solid state batteries

Li-ion batteries have played a key role in the portable electronics and electrification of transport in modern society. Nevertheless, the limited highest energy density of Li-ion batteries is not sufficient for the long-term needs of society. Since lithium is the lightest metal among all metallic elements and possesses the lowest redox potential of -3.04 V vs. standard hydrogen electrode, it delivers the highest theoretical specific capacity of 3860 mA h g(-1) and a high working voltage of full batteries which causes a great interest in electrochemical energy storage systems. Lithium-sulfur, lithium-oxygen and corresponding all solid state batteries based on metal lithium anode have received widely attention owing to their high energy densities. However, the problems in the cathode, electrolyte and anode of these three systems restrict their practical application. In this review, the research status and problems of these three energy storage systems are summarized and the challenges and future perspectives are also outlined.