Borates as promising electrode materials for rechargeable batteries

Abstract

Lithium ion batteries (LIBs) have been extensively applied in our daily life, and they are playing more and more important role in our societies. To further improve their electrochemical performances or find out some alternative rechargeable batteries to better satisfy the requirements of our lives, exploration of novel electrode materials or modifications of known ones is the one of the main choices. There are a large number of electrode materials belonging to the polyanion-type, which have more stable structures than the other ones during electrochemical cycling, therefore attracting widespread interest all over the world. Among them, phosphates, silicates, and sulphates have been summarized systematically for their potentials on energy storage, however, as far as we know, there is no a specialized review to address borates. Given that a number of borates have been studied as cathode or anode materials for LIBs, and several ones also have been investigated their potentials for other types of rechargeable batteries beyond LIBs, including sodium ion batteries (SIBs), magnesium-ion batteries (MIBs), and Zn-air batteries, it is necessary to summarize them and give some meaningful discussions to promote their further development. This work addresses almost all the known borate-type electrodes for LIBs and beyond. The involved borates in this work are classified into several subgroups according to their chemical compositions, and their syntheses, crystal structures, electrochemical performances, advantages/disadvantages, and potentials are introduced one by one. Finally, several future prospects on borate-based electrode material for rechargeable batteries are proposed.