Understanding the mechanisms of mixed-ion cathode materials for aqueous and non-aqueous lithium/sodium-ion batteries – A review

In spite of reliability and high-energy density of lithium-ion batteries (LIBs), scarcity of Li and safety concerns have prompted the need to develop new-alternate systems. Sodium-ion batteries (SIBs) are becoming increasingly popular in this regard. Their progress is hampered by poor electrochemical performances caused by slow Na-ion diffusion-kinetics. To address these concerns, new concepts and new battery technology, such as the fabrication of hybrid-ion and mixed-ion batteries, have been proposed. In this review, we explored the significance of mixed-ion batteries and mixed-ion electrolytes for aqueous and non-aqueous batteries.