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 ma-terials 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 perfor-mance can be credited to the Co2+ coordination repressing the electrode dissolution and improving the structure stability.

Automated summary

Sodium-ion batteries (SIBs) are considered as a promising candidate for next-generation battery systems, but the design of electrode materials still faces challenges such as volume expansion and low capacity. Organic electrode materials with structural flexibility have attracted attention for their potential in mitigating volume expansion. However, most organic electrode materials suffer from dissolution in electrolytes and capacity fading. In this study, the use of Co2+ coordination effectively addressed the shuttle effect and improved the electrochemical performance of the Co(H2salphdc) electrode.