All-carbon lithium capacitor based on salt crystal-templated, N-doped porous carbon electrodes with superior energy storage

Abstract

In the pursuit of a lithium ion capacitor (LIC) with higher energy density and lower cost, the all-carbon symmetric-like LIC (ACS-LIC) has recently risen to prominence. In this article, we report a successful example of ACS-LIC synthesized by constructing both anode and cathode with one designed porous carbon material, prepared by a one-pot method and the cheap precursor methyl cellulose. By employing the salt crystal templates and N-doping, the as-obtained materials possess a unique interconnected porous carbon network with hierarchical pores and abundant active sites, showing low internal resistance, good wettability, high conductivity, and rich pseudocapacitance. The resultant NPC//NPC ACS-LIC device exhibited outstanding energy-power characteristics. Even at the super-large power density of 66 000 W kg⁻¹, it can still achieve a high energy density of 70 W h kg⁻¹. More importantly, the NPC//NPC ACS-LIC device demonstrates state-of-the-art cycling performance. After 10 000 cycles at 2 A g⁻¹, the performance is retained at nearly 100%; even when tested at 10 A g⁻¹, the device can still deliver 80.0% retention after 20 000 cycles, with only 0.001% fading per cycle, which is superior or at least comparable to the current state-of-the-art LICs.