All alginate-derived high-performance T-Nb2O5/C//seaweed carbon Li-ion capacitors

Abstract

Lithium-ion capacitors (LICs) have attracted intense attention due to their high energy/power densities and good stability. However, their performance is severely limited by the imbalance in reaction kinetics and electrochemical capacity between the faradaic battery-like anodes and non-faradic capacitive cathodes. Here, we propose an all alginate-derived LIC assembled with a three-dimensional porous orthorhombic phase Nb₂O₅/C hybrid as the anode, seaweed-derived carbon as the cathode and sodium alginate (SA) as the electrode binder. The increase in the rate performance of the anode and the capacity of the cathode efficiently mitigates the mismatch between the counter electrodes, and the SA binder provides facilitated access for Li ions to the surfaces of electrode materials. The all alginate-derived LIC exhibits high energy (143.9 W h kg⁻¹ at 87.6 W kg⁻¹) and power (17.5 kW kg⁻¹ at 75.1 W h kg⁻¹) densities with a superior cyclability (84.6% capacity retention after 3000 charge–discharge cycles), surpassing those of previous Nb₂O₅-based LICs. This work provides a novel design strategy for the electrodes of next-generation high-performance LICs.