The Advance and Perspective on Electrode Materials for Metal–Ion Hybrid Capacitors

Abstract

High power density supercapacitors that use reversible ion adsorption to store charge at the electrode/electrolyte interface remain functional after hundreds of charge/discharge cycles. [1][2][3] A series of carbonaceous materials such as activated carbon, graphite, fullerenes, graphene, and mesoporous carbon have been proposed to boost the performance of supercapacitors. [4,5] Among them, activated carbons with large specific surface area (%3000 m 2 g À1 ) are favored in supercapacitor designs by forming an electric double layer, thus ensuring the long-term stability. [6] Nevertheless, they offer a relatively low energy density. The capacity of supercapacitors is far from meeting the requirements for powering a variety of ubiquitous portable and flexible electronic devices. Limited gravimetric and volumetric energy densities remain serious issues for the commercialization of supercapacitor. Apart from supercapacitor, battery is another important component of energy storage system. Compared with the performance of supercapacitor, battery shows a low power density because the chemical reactions occur within the electrode material. Considering these limitations, research focus has been desperately put on the metal-ion hybrid capacitor (MHC) combining the merits of battery and supercapacitor. The setup of MHC is composed of capacitor-type and battery-type electrode materials. [41][42][43][44][45] A large part of the advantage of MHCs is due to their higher energy density than supercapacitors and higher power density than batteries without sacrificing cycling stability. [46][47][48][49][50] Using the concept of MHC is to both store and deliver large amounts of energy in devices. Therefore, MHCs have been extensively investigated. However, the high reactivity of alkali metals and the rising cost of scarce lithium resources have driven us to develop multivalent MHCs. Multivalent MHCs possess the merits of abundant resources, high safety, and high energy density owing to their multielectron energy storage process. Few studies have focused on describing a comprehensive review of MHCs, including Li, Na, K, Zn, Mg, Ca, and Al ion capacitors. Therefore, this review is concerned with research activities on electrode materials for MHC and provides a perspective on the future development of electrochemical energy storage technology.

Recent trends, challenges, and perspectives in piezoelectric‐driven self‐chargeable electrochemical supercapacitors

“…The presence of a piezoelectric separator in SCSPCs enables self‐charging whenever the device is subjected to external mechanical stimuli because the generated piezo potential across the piezo separator acts as a power source. Here, it is worth mentioning that the electrochemical reactions that occur during the self‐charging process will be like that of the conventional charging mechanism of an SC electrode or device as suggested in previous studies 36,68–70 . The major difference is that the piezo separator enables charging via mechanical forces instead of a conventional power source.…”

“…Here, it is worth mentioning that the electrochemical reactions that occur during the self-charging process will be like that of the conventional charging mechanism of an SC electrode or device as suggested in previous studies. 36,[68][69][70] The major difference is that the piezo separator enables charging via mechanical forces instead of a conventional power source. The fabrication, testing, and performance of SCSPCs are discussed in the later section.…”

A Review on the Conventional Capacitors, Supercapacitors, and Emerging Hybrid Ion Capacitors: Past, Present, and Future

“…Therefore, the appearance of emerging capacitors containing metal ion hybrid capacitors (HCs) and dual‐ion capacitors (DICs) is expected to enlarge energy density without weakening power density. [ 8 ]…”

“…Therefore, the appearance of emerging capacitors containing metal ion hybrid capacitors (HCs) and dual-ion capacitors (DICs) is expected to enlarge energy density without weakening power density. [8] For the conventional capacitors, supercapacitors, and emerging capacitors, the electrode materials or dielectric materials are one of the most paramount components for affecting their electrochemical performance. Hence, the breakthrough in electrode and dielectric materials promoted the development of EES devices.…”

Efficient Recovery Annealing of the Pseudocapacitive Electrode with a High Loading of Cobalt Oxide Nanoparticles for Hybrid Supercapacitor Applications

“…Electrochemical energy-storage/power-supply systems consist of energy storage batteries and high-power density supercapacitors. However, in order to fill the gap in energy/power capability of these technologies when combined together to create systems with a continuous energy and power storage/delivery spectrum and fulfill the ever-increasing power demands of newly emerging devices, the evolution of hybrid supercapacitors is crucial and has attracted huge interest in recent years with a large number of studies focusing on the development of hybrid supercapacitors and materials for such device structures published [ 1 , 2 , 3 , 4 ]. According to the charge storage mechanism, supercapacitors are classified into three main types: (i) electric double-layer capacitors, (ii) pseudocapacitors, and (iii) hybrid supercapacitors.…”