Towards High-Performance Supercapacitor Electrodes via Achieving 3D Cross-Network and Favorable Surface Chemistry

Abstract

Transition metal phosphides/phosphates (TMPs) are considered appealing electrode materials in energy-related fields, especially in supercapacitors. However, the dilemma of inadequate electrode kinetics and dimensional unreliability evoked by a huge volume variation during cycling significantly plagues their progress. To mitigate this issue, in this work, a 3D cross-network in situ assembled via self-derived N-doped carbon hybrid Ni-Co-P/POx 2D sheets is fabricated. Particularly, high-Fermi-level N-doped carbon well confines Ni-Co-P/POx nanoparticles at the molecular level, and N-doping leads to redistribution of spin/electron density in the carbon skeleton, effectively regulating the electron environment of nearby Ni–Co-based moieties, resulting in a relatively lower surface work function, as known via experimental and Kelvin probe force microscopy (KPFM) results, which favors electron flee from the electrode surface and facilitates electron transport toward a rapid supercapacitor response. Moreover, the well-defined 3D cross-network architectures featured with in-plane pores and interconnected with each other can provide more ion/electron transfer pathways and 2D sheets with excellent surface chemistry available for sustainable ion/electron mobility, synergistically affording the favorable electrode kinetics. Accordingly, the resultant Ni-Co-P/POx@NC electrode shows admirable specific capacitance, excellent rate survivability, and long-term cyclability. The as-assembled asymmetric device exhibits remarkable energy and power outputs (48.5 Wh kg–1 and 7500 W kg–1), superior to many reported devices. Furthermore, our devices possess the prominent ability to power a commercial electronic thermometer for 1560 s at least, showcasing superb application prospects.

Surface chemistry and structure manipulation of graphene-related materials to address the challenges of electrochemical energy storage

“…The modification of surface chemistry of electrode materials plays a critical role in hindering gas evolution in lithium ion batteries, 40 enhancing the stability of lithium–air batteries, 41 improving electron conductivity of electrode materials of SIBs, 42 increasing the wettability of electrodes, and increasing the electrode kinetics of SCs. 43 Introducing specific surface functional moieties on the graphene surface is an important strategy to control its electrochemical activity and improve its electrochemical performance. Graphene is chemically stable, so specific strategies should be used for its functionalization.…”

A Ferricyanide Anion-Philic Interface Induced by Boron Species within Carbon Framework for Efficient Charge Storage in Supercapacitors

“…Supercapacitors (SCs) have drawn substantial attention as they offer a long cycle life, excellent stability, and high power density. 1 Nevertheless, SCs have a relatively low energy density compared with batteries or fuel cells, which still hinders their practical applications. 2 As a result, redox electrolyte-enhanced SCs (R-SCs), in which the soluble redox substances (SRSs, while [Fe(CN) 6 ] 4−/3− is most commonly used) are added in the electrolyte to provide the extra reversible surface redox capacitance, have been proposed to achieve the goal of boosting the capacitance and energy density.…”

“…Supercapacitors (SCs) have drawn substantial attention as they offer a long cycle life, excellent stability, and high power density . Nevertheless, SCs have a relatively low energy density compared with batteries or fuel cells, which still hinders their practical applications .…”