Defect-Engineered 3D Cross-Network Co₃O_4–xN_x Nanostructure for High-Performance Solid-State Asymmetric Supercapacitors

Abstract

A 3D cross-network Co 3 O 4−x N x nanostructure is obtained from the cobalt−alanine complex (Co(C 3 H 5 O 2 N) 2 ) by amino acid self-assembly and subsequent pyrolysis. In this process, Co(C 3 H 5 O 2 N) 2 forms a 2D sheet structure by intermolecular selfassembly; then, the 2D sheet structure self-assembles to form a 3D cross-network nanostructure, which undergoes pyrolysis to form Co 3 O 4−x N x . The resulting Co 3 O 4−x N x has a 3D cross-network nanostructure with a high specific surface area and suitable pore diameter. The unique 3D cross-network nanostructure of Co 3 O 4−x N x can supply a large amount of active sites, and the pores can promote ion migration, which can reduce volume expansion during cycling. Importantly, the amino acid self-assembly strategy is performed at the molecular level so that the N atoms in alanine (C 3 H 7 O 2 N) migrate in the molecule to form in-situ doping and simultaneously create defects. Defect engineering can facilitate rapid transport of electrons in the electrode, further effectively improving the conductivity of the material, which has been further proved by density functional theory calculations. N-doping can also improve the hydrophilicity of the material. Hence, the Co 3 O 4−x N x -300 electrode shows high specific capacitance (666 Fg −1 at 1 Ag −1 ) and outstanding cycling stability (a capacitance retention rate of 74.1% after 10,000 cycles). In addition, an all-solid-state asymmetric supercapacitor based on the Co 3 O 4−x N x -300 cathode and active carbon anode displays a high energy density of 33.2 W h kg −1 at 751.1 W kg −1 and long cycling stability with a capacitance loss of 15.8% after 5000 cycles. All the experiment results show that the Co 3 O 4−x N x material has great potential as a supercapacitor material. KEYWORDS: supercapacitor, amino acid self-assembly, Co 3 O 4−x N x , defect-engineered, all-solid-state asymmetric device

Tuned Bimetallic Fe–Ni Thiophosphides as Advanced Battery Materials for Asymmetric Electrochemical Supercapacitors with Outstanding Energy Density

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Triethanolamine assisted synthesis of bimetallic nickel cobalt nitride/nitrogen-doped carbon hollow nanoflowers for supercapacitor

“…The peaks at 38.9°, 42.1°, 44.5°, 58.5°, 70.6° and 78.4° could be attributed to the (110), (002), ( 111), ( 112), (300) and (113) 002), ( 101), ( 102), ( 110) and ( 103) crystal faces of Co 2 N 0.67 (JCPDS:10-0280). All these peaks are sharp and narrow due to the good crystallinity of the material [30] . Moreover, no peaks were observed for nickel oxide or cobalt oxide, suggesting pristine metal nitrides were obtained.…”

Deciphering the In Situ Surface Reconstruction of Supercapacitive Bimetallic Ni-Co Oxyphosphide during Electrochemical Activation Using Multivariate Statistical Analyses

“…Supercapacitors are promising energy storage platforms owing to their rapid charging speed and long-term stability . However, their full potential is yet to be realized, mainly due to their lower energy content compared to batteries. , Hybrid devices with both battery and supercapacitor characteristics are thus a rational approach for improved energy storage applications.…”

“…9,10 ECA is a widely recognized process for various electrochemical systems, such as supercapacitors, batteries, and oxygen and hydrogen evolution reactions. In carbon-based materials, ECA could be explained due to one of several phenomena: (1) the extensive accessibility to the multiporous layer, 11 (2) enhanced hydrophilicity of the surface, 12,13 and (3) graphitization in certain circumstances. 14 ECA is, however, often overlooked for transition metal-based materials.…”