Crystal-defect enriched graphite sieve for lithium-ion capacitors

Graphite is a widely used anode material in lithium-ion capacitors for its remarkable structural stability and low lithium insertion voltage. However, the sluggish diffusion of lithium ions results in poor rate performance, thereby constraining the power density capabilities. This study aims to prepare graphite sieve with abundant crystal defects and thin walls using carbon sieves as precursors. Following atomic reconfiguration during graphitization, the disordered carbon wall evolved into graphite wall with crystal defects like vacancies and dislocations. These defects expanded the interlayer spacing of graphite sieve, thereby enhancing the pathways available for lithium-ion transport. Moreover, the thin graphite enabled faster lithium-ion diffusion by shortening the travel distance. Consequently, the graphite sieve exhibited superior rate performance, delivering a reversible specific capacity of 65 mA h g⁻¹ at 30C, and achieving a high capacity retention rate of 96.5% after 1000 cycles at 0.5C. These results confirmed the superior rate performance and cycling stability of graphite sieve. The Li-ion capacitor utilizing graphite sieve as anode exhibited a power density of 0.88 kW kg⁻¹ and an energy density of 200 Wh kg⁻¹. Furthermore, even at a power density of 66.0 kW kg⁻¹, the energy density remained at 82.5 Wh kg⁻¹. This innovative graphite sieve anode offers a potential solution for next-generation high-power and high-energy-density lithium-ion batteries and capacitors.