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Organic electrode materials have attracted much attention in the field of batteries owing to their low-cost, structure diversity and environmental friendliness. However, most of them suffer from low electrical conductivity, sluggish reaction kinetics, and poor cycle life. In this work, we develop a strategy of fabricating a naphthalene diimide-based sodium salt cathode with high electrical conductivity for facilitating the charge transfer and accelerating the reaction kinetics by the dissolution/reprecipitation process. The recrystallization process of naphthalene molecules in water enhances intermolecular π–π interactions, leading to the formation of a uniform rod-like morphology and significantly increasing its electrical conductivity, which allows fast charge transfer kinetics and high ionic conductivity of organic electrodes in sodium-ion batteries. Therefore, the recrystallized organic cathode (NDI-ONa-r) exhibits a high specific capacity of 145 mA h g⁻¹ at 0.1 A g⁻¹, excellent fast charge/discharge performance (70 mA h g⁻¹ at 20 A g⁻¹, about 127C), and an ultra-long cycle life of 30 000 cycles at 10 A g⁻¹ with a capacity retention of 87%. As a result, the NDI-ONa-r//HC full cells also show a high specific capacity of 140 mA h g⁻¹ at 0.1 A g⁻¹ and good rate performance. Our work presents a potential way to fundamentally facilitate fast electron transport and ion diffusion in organic electrode materials, which would motivate their application in high-performance sodium-ion batteries.

Organic lithium salts are promising cathode candidates for sustainable lithium-ion batteries (LIBs) due to their synthetic simplicity and environmental friendliness. However, their practical application is often thwarted by active material dissolution and sluggish redox kinetics, stemming from limited conjugation and deficient electronic conductivity. Herein, we report a naphthalenediimide-based lithium salt (NDI-OLi) designed with a robust π-conjugated structure and high aromaticity to enhance electronic transport. Experimental and theoretical studies reveal that the relatively high electronic conductivity, rapid reaction kinetics, and stable delocalized electronic geometry of the NDI-OLi cathode are key factors enabling sufficient coordination between carbonyl sites and lithium ions. As a result, the NDI-OLi electrode presents a high reversible capacity of 160 mAh g ⁻¹ at 0.1 A g ⁻¹ , excellent rate performance (99.9 mAh g ⁻¹ at 8 A g ⁻¹ ), and exceptional cycling stability with 85% capacity retention after 5000 cycles at 1 A g ⁻¹ . This work opens up new avenues for developing highly conductive and stable organic salt cathodes toward high-performance and durable LIBs.

Redox-active organic materials have arisen as promising electrode materials for rechargeable batteries owing to their merit of structural diversity and environmental compatibility. However, their practical application in sodium ion batteries (SIBs) has been hindered by the high dissolution in liquid electrolytes and the sluggish redox kinetics. Herein, a series of π-conjugated N-heterocyclic quinones (TTAQ, DPT, DNQ-PQ, and DNQ-PTO) with chelation groups were systematically developed. Among them, DNQ-PTO exhibited exceptional performance, delivering a reversible capacity of ∼275 mA h g⁻¹ at 0.1 A g⁻¹, which referred to a six-electron redox process involving a four-electron transfer for CO/C–O and a two-electron transfer for the CN/C–N group. Moreover, the DNQ-PTO cathodes demonstrated remarkable rate capability, superior cycling stability (∼89% capacity retention after 6000 cycles at 5 A g⁻¹), and excellent low-temperature performance (∼91.4% capacity retention over 100 cycles at −40 °C). The outstanding electrochemical performance of DNQ-PTO stemmed from its extended conjugation system and well-dispersed chelation groups, which facilitated efficient charge delocalization and structural stability. This work demonstrated that the critical challenges in capacity, stability, and kinetics of organic electrode materials could be addressed through molecular structure optimization, which established a new paradigm for high-performance organic electrodes.

The development of covalent organic framework (COF) cathodes for low-temperature sodium-ion batteries (SIBs) remains challenging due to sluggish reaction kinetics at low-temperature temperatures. Herein, we demonstrate a donor-acceptor (D-A) covalent organic framework constructed from p-type triphenylamine and n-type naphthalimides units as a robust cathode for low-temperature SIBs. The stable naphthalimide-based building blocks endow the constructed D-A framework with faster charge transport capability and enhanced redox kinetics, achieving a capacity of 135 mAh g^-1 at 0.1 A g^-1 and an impressive capacity retention of 80% after 2000 cycles at 1 A g^-1. Remarkably, it maintains high capacities of 108 mAh g^-1 at 0 °C and 85 mAh g^-1 at -20 °C, with a capacity retention rate of 91% after 300 cycles at -20 °C. The dual-ion co-storage mechanism of Na⁺ and PF₆⁻ has been elucidated through in situ spectroscopic characterization and theoretical calculations. This work provides a feasible molecular design strategy towards stable and high-performance porous organic cathodes for low-temperature SIBs.