Cobalt coordination modified double-schiff-base with low solubility as a long-cycle life anode for sodium-ion batteries

Sodium-ion batteries (SIBs) have been recently considered as an intriguing candidate for next-generation battery systems with their advantages in large-scale energy storage applications. However, the design of electrode materials of SIBs still suffers from severe volume expansion and low capacity caused by the larger ion radius, high re-dox potential and heavy atom weight of Na. Organic electrode materials with structural flexibility have attracted great attention recently for their potential in alleviating volume expansion. However, most organic electrode materials suffer from dissolution in electrolytes and consequent capacity fading during the long-term cycling process. In this work, a method coordinating with Co²⁺ was applied to solve the shuttle effect of H₄salphdc (N, N’-phenylene-bis-(salicylideneimine) dicarboxylic acid). By virtue of the Co²⁺ coordination, the Co(H₂salphdc) electrode delivered a desirable discharge capacity of 123 mAh g^?1 after 1500 cycles at the current density of 200 ?mA ?g^?1, while the H₄salphdc electrode exhibited severe capacity fading. Such excellent electrochemical performance can be credited to the Co²⁺ coordination repressing the electrode dissolution and improving the structure stability.