S, O dual-doped porous carbon derived from activation of waste papers as electrodes for high performance lithium ion capacitors

Abstract

To circumvent the imbalances of electrochemical kinetics and charge-storage capacity between Li⁺ ion battery anodes and capacitive cathodes in lithium-ion capacitors (LICs), dual carbon based LICs are constructed and investigated extensively. Herein, S, O dual-doped 3D net-like porous carbon (S-NPC) is prepared using waste paper as the carbon source through a facile solvothermal treatment and chemical activation. Benefiting from the combination effect of the rich S,O-doping (about 2.1 at% for S, and 9.0 at% for O), high surface area (2262 m² g⁻¹) and interconnected porous network structure, the S-NPC-40 material exhibits excellent electrochemical performance as both cathode material and anode material for LICs. S, O doping not only increases the pseudocapacity but also improves the electronic conductivity, which is beneficial to reduce the mismatch between the two electrodes. The S-NPC-40//S-NPC-40 LIC delivers high energy densities of 176.1 and 77.8 W h kg⁻¹ at power densities of 400 and 20 kW kg⁻¹, respectively, as well as superior cycling stability with 82% capacitance retention after 20 000 cycles at 2 A g⁻¹. This research provides an efficient method to convert waste paper to porous carbon electrode materials for high performance LIC devices.