Polymer binder: a key component in negative electrodes for high-energy Na-ion batteries

In the hope of finding potential replacements of Li-ion batteries, in which lithium, a minor-metal is used as ion carrier, Na-ion batteries that are operable at high voltage, higher than 3 volts, under ambient condition are attractive to develop much low-priced energy systems. However, owing to the larger atomic/ionic volume of sodium than that of lithium, severer volume change upon sodiation/desodiation inevitably deteriorates the performance of Na-ion batteries. Polymer binder, as a key component in maintaining the structural integrity during the volume change with pre-formed SEI effect, has not been thoroughly discussed for negative electrode in Na-ion batteries. In this review, we summarized several advanced polymer binders that have already been reported, and introduced their recent advances for high capacity electrode in Na cells.