Advanced electrode materials embrace the key to the fundamental progress in rechargeable ion battery systems, which are essential to meet the finite nature of fossil fuels and the growing energy demands for clean and renewable energy. Metal phosphides in particular offer opportunities in rechargeable ion batteries owing to the extraordinarily high theoretical capacity and suitable redox potential. Notwithstanding these advantages, metal phosphides suffer from drastic volume variation during the electrochemical cycling process, resulting in relatively low capacity retention. Constructing metal phosphide–carbon heterostructures is an engrossing approach, which is because nanocarbon possesses bifunctional features that afford an electronic pathway and alleviate large volume expansion. Thus, the hybridization strategies of metal phosphides with different carbonaceous species are specifically highlighted in this review, followed by the illustration of how a robust understanding of these carbon matrixes within composites provides fundamental insights into the electronic conductivity, cycling durability, and rate capacity in metal phosphide electrodes. Meanwhile, the systematic discussion of the Li+/Na+/K+ ion storage mechanism in metal phosphides has also been expressly represented. Based on the insights, we outline the critical issues and challenges of metal phosphide/carbon heterostructures that need to be addressed to broaden their contribution in rechargeable ion batteries.

Progress and perspective of metal phosphide/carbon heterostructure anodes for rechargeable ion batteries

Efficient degradation of organic dye using Ni-MOF derived NiCo-LDH as peroxymonosulfate activator.

• The energy storage mechanisms of electric double-layer supercapacitors are presented. • Several commonly used supercapacitor carbon electrode materials are shown. • Prospects for further research and development of the supercapacitor carbon materials. The role of supercapacitors in the energy storage industry is gaining importance due to their high power density and long life cycle. In recent years, supercapacitors have made numerous breakthroughs. Carbon materials are the most commonly used electrode materials for supercapacitors and the researches of carbon materials are significant for developing supercapacitors. Herein, this article presents the energy storage mechanisms of supercapacitors and the commonly used carbon electrode materials. The energy storage mechanism includes commonly used energy storage models and the verification and in-depth understanding of these models using molecular dynamic simulation and in-situ technology. The carbon electrode materials section introduces the most commonly used carbon materials and their applications in the field of supercapacitors. Finally, the development trend of carbon-based supercapacitors is prospected. 

A review of carbon materials for supercapacitors

Metal-organic frameworks as highly efficient electrodes for long cycling stability supercapacitors

Black phosphorus (BP) has recently attracted significant interest due to its unique electronic and optical properties. Doping is an effective strategy to tune a material's electronic structures, however, the direct and controllable growth of BP with a high yield and its doping remain a great challenge. Here we report an efficient short-distance transport (SDT) growth approach and achieve the controlled growth of high quality BP with the highest yield so far, where 98% of the red phosphorus is converted to BP. The doping of BP by As, Sb, Bi, Se and Te are also achieved by this SDT growth approach. Spectroscopic results show that doping systematically changes its electronic structures including band gap, work function, and energy band position. As a result, we have found that the air-stability of doped BP samples (Sb and Te-doped BP) improves compared with pristine BP, due to the downshift of the conduction band minimum with doping. This work develops a new method to grow BP and doped BP with tunable electronic structures and improved stability, and should extend the uses of these class of materials in various areas.

High Yield Growth and Doping of Black Phosphorus with Tunable Electronic Properties

Urchin-like FeS2 hierarchitectures wrapped with N-doped multi-wall carbon nanotubes@rGO as high-rate anode for sodium ion batteries

In
this work, a type of high-performance electrode material of
Ni/C/rGO-n [n = wt % of reduced
graphene oxide (rGO)] derived from nickel-based metal–organic
framework (Ni-MOF) for supercapacitors is successfully prepared. First,
a hydrogen-bonding-assisted approach to continuous growth of Ni-MOFs
on graphene oxide (GO) sheets is developed through the application
of a hexadentate ligand, hexakis­(4-carboxylphenoxy)­cyclotriphosphazene
(CTP-COOH), as the anchor with multiple biting points. The thicknesses
of the obtained layer cakelike Ni-MOF/GO-n (n: wt % GO) nanosheet composites with GO as the filling
content can be controlled by tuning the ratio between GO and Ni-MOF.
During the subsequent process of thermolysis treatment of Ni-MOF/GO-n composites, GO acts as a “hard” template
and thus the decomposition of loaded metal–organic frameworks
(MOFs) affords highly porous metal/C composites homogeneously embedded
on the rGO matrix. This highly porous structure enhances the stability
of Ni/C composites profoundly. Besides, both the rGO matrix and porous
metal/C composites can provide an expressway for electron transport
and shorten ion diffusion paths for greatly enhanced diffusion kinetics
within the electrode materials, therefore leading to a superior rate
capability. Moreover, application of the hexadentate ligand CTP-COOH
with a six-membered ring backbone, which consisted of N and P atoms
linked together alternatively, enables self-doping of N, O, and P
to the derived materials. It is proven that the electrochemical performances,
especially the stability, are remarkably enhanced for the derived
Ni/C/rGO-n composites compared with the bare Ni-MOF-derived
Ni/C composites. More importantly, this work pioneeringly demonstrates
the potential application of MOF derivatives in energy storage devices.

Metal-Organic-Framework-Derived N-, P-, and O-Codoped Nickel/Carbon Composites Homogeneously Decorated on Reduced Graphene Oxide for Energy Storage

Metal-organic framework derived high-content N, P and O-codoped Co/C composites as electrode materials for high performance supercapacitors

Hierarchical nanosheet-based MoS2–NiS nanotubes coated with N-doped carbon (MNS-HNT@NC) composites were fabricated using a template-assisted hydrothermal and post-sulfidation strategy. The composite, with a tube-like structure, is mainly constructed by ultrathin MoS2–NiS nanosheets. Such hierarchical nanosheet-based nanotubes possess high surface-to-volume ratios, which can release mechanical stress during Na ion insertion/extraction and shorten the pathways for Na ion/electron transport. Furthermore, the internal void space in the nanotube can effectively accommodate the large volume change of the electrode, thereby alleviating structural collapse of the electrode. On the other hand, abundant lattice defects and the internal electric field induced by the heterostructure of MoS2 and NiS boost the Na ion intercalation kinetics. In addition, the MoS2 and NiS nanocrystals uniformly dispersed in the composite can act as mutual spacers, thereby avoiding aggregation during cycling. The MNS-HNT further coated with N-doped carbon can reduce contact resistance and restrict the large volume change, preventing electrode pulverization. Benefiting from these advantages and using an ether-based electrolyte, MNS-HNT@NC, as anode for SIBs, delivers a considerable specific capacity (707 mA h g−1 at 0.1 A g−1), high initial coulombic efficiency of 94%, stable long-term cycling stability (391 mA h g−1 maintained after 700 cycles at 2 A g−1) and superior rate performance (342 mA h g−1 at 10 A g−1).

Lianyi Shao

Papers

Urchin-like FeS2 hierarchitectures wrapped with N-doped multi-wall carbon nanotubes@rGO as high-rate anode for sodium ion batteries

Metal-Organic-Framework-Derived N-, P-, and O-Codoped Nickel/Carbon Composites Homogeneously Decorated on Reduced Graphene Oxide for Energy Storage

Metal-organic framework derived high-content N, P and O-codoped Co/C composites as electrode materials for high performance supercapacitors

Hierarchical MoS2-NiS nanosheet-based nanotubes@N-doped carbon coupled with Ether-based electrolytes towards high-performance Na-ion Batteries

Niobium Carbide as a Promising Pseudocapacitive Sodium-Ion Storage Anode