Lithium-ion batteries (LIBs) have achieved huge success in the past few decades, due to mature technologies, low cost, and high charge-discharge efficiency. However, the development

Garnet-type electrolytes suffer from unstable chemistry against air exposure,w hichg enerates contaminants on electrolyte surface and accounts for poor interfacial contact with the Li metal. Thermal treatment of the garnet at > 700 8 8C could remove the surface contaminants,y et it regenerates the contaminants in the air,and aggravates the Li dendrite issue as more electron-conducting defective sites are exposed. In ad eparture from the removal approach,h ere we report an ew surface chemistry that converts the contaminants into af luorinated interface at moderate temperature < 180 8 8C. The modified interface shows ahigh electron tunneling barrier and alow energy barrier for Li + surface diffusion, so that it enables dendrite-proof Li plating/stripping at ah igh critical current density of 1.4 mA cm À2 .M oreover,t he modified interface exhibits high chemical and electrochemical stability against air exposure,which prevents regeneration of contaminants and keeps high critical current density of 1.1 mA cm À2 .T he new chemistry presents apractical solution for realization of highenergy solid-state Li metal batteries.

Sun, wind and tides have huge potential in providing us electricity in an environmental-friendly way. However, its intermittency and non-dispatchability are major reasons preventing full-scale adoption of renewable energy generation. Energy storage will enable this adoption by enabling a constant and high-quality electricity supply from these systems. But which storage technology should be considered is one of important issues. Nowadays, great effort has been focused on various kinds of batteries to store energy, lithium-related batteries, sodium-related batteries, zinc-related batteries, aluminum-related batteries and so on. Some cathodes can be used for these batteries, such as sulfur, oxygen, layered compounds. In addition, the construction of these batteries can be changed into flexible, flow or solid-state types. There are many challenges in electrode materials, electrolytes and construction of these batteries and research related to the battery systems for energy storage is extremely active. With the myriad of technologies and their associated technological challenges, we were motivated to assemble this 2020 battery technology roadmap.

Recycling of spent lithium-ion batteries has become a critical issue recently for both environmental concerns and reutilization of resources. Among the existing recycling strategies, direct regeneration is largely encouraged from...