Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

https://hal.archives-ouvertes.fr/hal-02417326/document

Materials for electrochemical capacitors

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

/pdf/a-review-of-electrode-materials-for-electrochemical-2cok5em0bo.pdf

A review of electrode materials for electrochemical supercapacitors

Electrochemical energy storage technology is based on devices capable of exhibiting high energy density (batteries) or high power density (electrochemical capacitors). There is a growing need, for current and near-future applications, where both high energy and high power densities are required in the same material. Pseudocapacitance, a faradaic process involving surface or near surface redox reactions, offers a means of achieving high energy density at high charge–discharge rates. Here, we focus on the pseudocapacitive properties of transition metal oxides. First, we introduce pseudocapacitance and describe its electrochemical features. Then, we review the most relevant pseudocapacitive materials in aqueous and non-aqueous electrolytes. The major challenges for pseudocapacitive materials along with a future outlook are detailed at the end.

https://hal.archives-ouvertes.fr/hal-01171774/document

Pseudocapacitive oxide materials for high-rate electrochemical energy storage

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Due to its high theoretical specific capacitance and high oxygen evolution potential, MnO2 has been considered as a promising positive electrode material for high-energy asymmetric supercapacitors (ASCs). However, the search for MnO2 positive electrodes with high specific capacitance and excellent rate performance for ASCs remains challenging. Herein, for the first time we report a novel strategy for the synthesis of Fe(CN)63− ion-modified MnO2/graphene ribbons (m-MnO2/GRs) as the positive electrode for high energy density ASCs. Benefiting from vertically aligned MnO2 grown on the interconnected graphene ribbon and Fe(CN)63− ion modification, the m-MnO2/GR exhibits a high specific capacitance of 435 F g−1, excellent rate capability and cycling stability. More importantly, the assembled m-MnO2/GR//GR ASC exhibits a high energy density of 57.8 W h kg−1 at a power density of 1.2 kW kg−1, as well as outstanding cycling stability with 100% capacitance retention after 10 000 cycles. More importantly, such a device can be charged/discharged within 0.79 s in an ultrafast manner to deliver a high specific energy of 10.5 W h kg−1 at an ultrahigh specific power of 48 kW kg−1. Thus, our strategy could be possibly used for the design and fabrication of new energy storage devices with high energy and power densities for future applications.

Fe(CN)63− ion-modified MnO2/graphene nanoribbons enabling high energy density asymmetric supercapacitors

Biomass-derived carbon is a promising sustainable anode material for sodium-ion batteries (SIBs). Although the electrochemical performance can be improved by introducing functional groups, the sele...

Wood-Derived Carbon with Selectively Introduced C═O Groups toward Stable and High Capacity Anodes for Sodium Storage.

Fabrication and characterization of multi-walled carbon nanotubes-based ink

Here, we report a novel Co3O4–graphene hybrid electrode material with high density Co3O4 nanoparticles (NPs) in a size range of 2–3 nm confined in a few-layered porous graphene nanomesh (PGN) framework driven by an electrochemical process. Raman spectra indicate that Co species preferentially anchor on the defective sites of the PGN, which results in markedly reduced irreversible Li storage and therefore significantly enhanced coulombic efficiency. The ultra-small Co3O4 NPs provide a large surface area and a short solid-state diffusion length, which is propitious to achieving a high Li ion capacity at high rate. Also, the few-layered graphene network with high electronic conductivity not only permits easy access to the high surface area of the Co3O4 NPs for the electrolyte ions, but also serves as a reservoir for high capacity Li storage. As a result, the Co3O4–PGN composite layers deliver an ultra-high capacity (1543 mA h g−1 at 150 mA g−1) and excellent rate capability (1075 mA h g−1 at 1000 mA g−1) with good cycling stability.

High density Co3O4 nanoparticles confined in a porous graphene nanomesh network driven by an electrochemical process: ultra-high capacity and rate performance for lithium ion batteries

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.201470017

Zhuangjun Fan

Papers

Fe(CN)63− ion-modified MnO2/graphene nanoribbons enabling high energy density asymmetric supercapacitors

Wood-Derived Carbon with Selectively Introduced C═O Groups toward Stable and High Capacity Anodes for Sodium Storage.

Fabrication and characterization of multi-walled carbon nanotubes-based ink

High density Co3O4 nanoparticles confined in a porous graphene nanomesh network driven by an electrochemical process: ultra-high capacity and rate performance for lithium ion batteries

Supercapacitors: Recent Advances in Design and Fabrication of Electrochemical Supercapacitors with High Energy Densities (Adv. Energy Mater. 4/2014)