Biomass carbon enabled charge transport network optimization in layered double hydroxides for high-rate energy storage

Abstract

Layered double hydroxides (LDH) are promising in electrochemical energy storage due to their superior theoretical capacity. Nonetheless, the self-agglomeration and poor conductivity of LDH limit their applications, especially during rapid charge–discharge processes. In this study, the charge transport network of LDH has been optimized using a synthesized bifunctional porous carbon to raise the performance of both electrodes and devices. The structure characterization and DFT simulation show that the fabricated porous structure and conductive skeleton facilitate high utilization of electrochemical active sites and charge transfer, thus augmenting the rate capability. The specific capacity of the composite NiCoLDH@NPC reaches 294.3 mA h g⁻¹, with approximately 70% capacity retention as the current density increases by fiftyfold, compared to that of the NiCoLDH of only 22.9%. The energy density of the assembled hybrid supercapacitor maintains 57.8 W h kg⁻¹ even as the power density escalates to a substantial 47 kW kg⁻¹, and the device shows remarkable cycling stability (10 000 cycles, 78.77%). NiCoLDH@NPC is also applied in zinc-ion batteries and demonstrates promising performance (154.4 mA h g⁻¹, 20 A g⁻¹). This composite strategy for LDH via a bifunctional matrix material provides an efficient path to improve high-rate energy storage.