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Abstract Developing low‐voltage carboxylate anode materials is critical for achieving low‐cost, high‐performance, and sustainable Na‐ion batteries (NIBs). However, the structure design rationale and structure‐performance correlation for organic carboxylates in NIBs remains elusive. Herein, the spatial effect on the performance of carboxylate anode materials is studied by introducing heteroatoms in the conjugation structure and manipulating the positions of carboxylate groups in the aromatic rings. Planar and twisted organic carboxylates are designed and synthesized to gain insight into the impact of geometric structures to the electrochemical performance of carboxylate anodes in NIBs. Among the carboxylates, disodium 2,2’‐bipyridine‐5,5’‐dicarboxylate (2255‐Na) with a planar structure outperforms the others in terms of highest specific capacity (210 mAh g⁻¹), longest cycle life (2000 cycles), and best rate capability (up to 5 A g⁻¹). The cyclic stability and redox mechanism of 2255‐Na in NIBs are exploited by various characterization techniques. Moreover, high‐temperature (up to 100 °C) and all‐organic batteries based on a 2255‐Na anode, a polyaniline (PANI) cathode, and an ether‐based electrolyte are achieved and exhibited exceptional electrochemical performance. Therefore, this work demonstrates that designing organic carboxylates with extended planar conjugation structures is an effective strategy to achieve high‐performance and sustainable NIBs. 

Developing high-capacity, stable, and sustainable K-ion batteries (KIBs) is an ongoing challenge due to the lack of high-performance and environmentally benign electrode materials. To address this challenge, organic electrode materials that are affordable, abundant, highly sustainable, highly tunable and flexible offer opportunities. Herein, we report a novel N-containing carboxylate salt, K 2 C 12 H 6 N 2 O 4 (K-DCA), with two bipyridine moieties and two carboxylate groups. The carboxylate- and pyridine-based active centers in K-DCA can reversibly react with four K-ions to provide a specific capacity of 163.3 mA h g −1 with a pair of redox plateaus centered at ∼0.8 V. When coupling with nitrogen-doped reduced graphene oxide (NrGO), the composite anode material, K-DCA-NrGO, demonstrates a high specific capacity of 225.25 mA h g −1 and increased capacity retention during long-term cycling. Additionally, the reaction kinetics and mechanism studies demonstrate that the composite exhibits low overpotentials, low interphase resistance, a partial pseudo-capacitance behavior, and stable chemical/morphological structures upon cycling, which contribute to the fast kinetics and long cycle life.