Metal Phosphides and Phosphates‐based Electrodes for Electrochemical Supercapacitors

Abstract

Phosphorus compounds, such as metal phosphides and phosphates have shown excellent performances and great potential in electrochemical energy storage, which are demonstrated by research works published in recent years. Some of these metal phosphides and phosphates and their hybrids compare favorably with transition metal oxides/hydroxides, which have been studied extensively as a class of electrode materials for supercapacitor applications, where they have limitations in terms of electrical and ion conductivity and device stability. To be specific, metal phosphides have both metalloid characteristics and good electric conductivity. For metal phosphates, the open-framework structures with large channels and cavities endow them with good ion conductivity and charge storage capacity. In this review, we present the recent progress on metal phosphides and phosphates, by focusing on their advantages/disadvantages and potential applications as a new class of electrode materials in supercapacitors. The synthesis methods to prepare these metal phosphides/phosphates are looked into, together with the scientific insights involved, as they strongly affect the electrochemical energy storage performance. Particular attentions are paid to those hybrid-type materials, where strong synergistic effects exist. In the summary, the future perspectives and challenges for the metal phosphides, phosphates and hybrid-types are proposed and discussed.

Ni12P5 Nanoparticles Hinged by Carbon Nanotubes as 3D Mesoporous Anodes for Lithium‐Ion Batteries

“…With the development of science and technology, energy products, such as electric vehicles (EVs), electric grids and mobile electrical devices, have been widely used in our daily life. Hence, there is a growing demand for energy storage systems . Lithium‐ion batteries (LIBs) as one of the promising power sources have been arousing intensive interest and research, due to the high working voltage, large capacity density, long cycle life, low self‐discharge, non‐memory effect as well as environmental friendliness .…”

3D‐Graphene Decorated with g‐C3N4/Cu3P Composite: A Noble Metal‐free Bifunctional Electrocatalyst for Overall Water Splitting

“…It is thereby highly intriguing to design durable, efficient and economically desirable non‐noble metal‐based electrocatalysts for complete water splitting. Due to presence of multi‐electron orbitals of phosphorus in transition metal phosphides, it showed better activity compared to metal oxides/hydroxides, as well as metal phosphides possess more metalloid characteristics and thereby leads to high electrical conductivity …”

“…Due to presence of multi-electron orbitals of phosphorus in transition metal phosphides, it showed better activity compared to metal oxides/hydroxides, as well as metal phosphides possess more metalloid characteristics and thereby leads to high electrical conductivity. [13,14] In contrast, non-metal-based materials which are consisting of earth-abundant elements (like C, H, O, and N) acting as catalytically active centers, have been recently recognized as a new class of low-cost and environmentally benign electrocatalyst. [10,12] Among them, graphitic carbon nitrides (g-C 3 N 4 ) with ultrahigh N content have been developed as HER and OER catalyst.…”

Synthesis of Homogeneous Hollow Co3O4 Microspheres for Enhanced Cycle Life and Electrochemical Energy Storage Performance

“…Hybrid supercapacitors, as an important energy storage device, possess high potential for application in many areas owing to several advantages, such as high power density, fast charge/discharge process, long‐term cycle life and eco‐friendly, which can shorten the big gap of power density and energy density between conventional capacitors and batteries. According to the charge storage mechanisms, supercapacitors can usually be divided into two types, one is a double‐layer capacitor that stores the charge at the interface between the electrode of the capacitor and the electrolyte solution, and the other is a pseudocapacitor that stores the charge by Faraday reaction occurring on the surface of the electroactive material on the electrode . Faraday pseudocapacitor have attracted wide attention, because it can be generated not only on the surface of the electrode, but also the active site of redox can penetrate into the interior of the electrode.…”

“…According to the charge storage mechanisms, supercapacitors can usually be divided into two types, one is a double-layer capacitor that stores the charge at the interface between the electrode of the capacitor and the electrolyte solution, and the other is a pseudocapacitor that stores the charge by Faraday reaction occurring on the surface of the electroactive material on the electrode. [5][6][7] Faraday pseudocapacitor have attracted wide attention, because it can be generated not only on the surface of the electrode, but also the active site of redox can penetrate into the interior of the electrode. Therefore, it has higher capacitance and energy density than electric double layer capacitors.…”