Sodium-ion capacitors can potentially combine the virtues of high power capability of conventional electrochemical capacitors and high energy density of batteries. However, the lack of high-performance electrode materials has been the major challenge of sodium-based energy storage devices. In this work, we report a microwave-assisted synthesis of single-crystal-like anatase TiO2 mesocages anchored on graphene as a sodium storage material. The architecture of the nanocomposite results in pseudocapacitive charge storage behavior with fast kinetics, high reversibility, and negligible degradation to the micro/nanostructure. The nanocomposite delivers a high capacity of 268 mAh g–1 at 0.2 C, which remains 126 mAh g–1 at 10 C for over 18 000 cycles. Coupling with a carbon-based cathode, a full cell of sodium-ion capacitor successfully demonstrates a high energy density of 64.2 Wh kg–1 at 56.3 W kg–1 and 25.8 Wh kg–1 at 1357 W kg–1, as well as an ultralong lifespan of 10 000 cycles with over 90% of capacity rete...

Pseudocapacitive Sodium Storage in Mesoporous Single-Crystal-like TiO2–Graphene Nanocomposite Enables High-Performance Sodium-Ion Capacitors

Amorphous manganese oxide deposits with nanostructures (denoted as a-MnO x .nH 2 O) were electrochemically deposited onto graphite substrates from 0.16 M MnSO 4 .5H 2 O with pH 5.6 by means of the potentiostatic, galvanostatic, and potentiodynamic techniques. The maximum specific capacitance of a-MnO x .nH 2 O deposits plated in different modes, measured from cyclic voltammetry at 25 mV s -1 , is about 230 F g -1 in a potential window of 1.0 V. The high electrochemical reversibility, high-power characteristics, good stability, and improved frequency responses in 0.1 M Na 2 SO 4 for these nanostructured a-MnO x .nH 2 O deposits prepared by electrochemical methods demonstrate their promising potential in the application to electrochemical supercapacitors. The nanostructure of a-MnO x .nH 2 O, clearly observed by means of a scanning electron microscope, was found to depend strongly on the deposition mode. The similar capacitive performance of all deposits prepared in different modes was attributable to their nonstoichiometric nature with a very similar oxidation state, demonstrated by XPS spectra.

Nanostructures and capacitive characteristics of hydrous manganese oxide prepared by electrochemical deposition

Nanostructured mesoporous carbon as electrodes for supercapacitors

Cathodic deposition of Ni(OH)2 and Co(OH)2 for asymmetric supercapacitors: Importance of the electrochemical reversibility of redox couples

Practical and theoretical limits for electrochemical double-layer capacitors

Advanced capacitors and their application

PURPOSE:To obtain a capacitor having a high operational breakdown voltage and a low internal resistance, by forming a foil-like electrode substance on a conductive substrate through using as an electrode layer a mixed composite substance which includes at least a conductive filler and a polysaccharides compound, and by winding up at least a pair of foil-like electrode substances via separators, and further, by impregnating the wound substances with alkaline water-soluble electrolyte. CONSTITUTION:An activated carbon slurry is created by the uniform dispersion of activated carbon powder and a acetylene black into the acetic acid solution of chitosan. By a dipping method, the activated carbon slurry is deposited on both surfaces of a nickel foil 1 of 20mum in thickness which is rough-surfaced by a chemical etching method. After the same is dried, films 2, 3 of an activated carbon electrode are formed on both surfaces of the nickel foil 1. A pair of obtained foil-like electrode substances 4, 5 is wound up via separators 6. Into the wound substances, the aqueous solution of sulphuric acid which is 30 in wt.% is used as an electrolyte for impregnation.

Electric double layer capacitor and manufacture thereof

Activated carbon for use in an electric double layer capacitor which has at least activated carbon, electrolyte solution and a separator, the activated carbon having properties of: the total specific surface area of 1000 m2/g or larger; the pore volume distribution of 400 μl/g or larger for the pores larger than 12 Å and smaller than 40 Å in diameter and of 50 μl/g or larger for the pores larger than 40 Å in diameter; and the total pore volume of 1000 μl/g or smaller.

Activated carbon for use in electric double layer capacitor and method of producing the same

A negative electrode for an electrochemical capacitor includes a current collector having electric conductivity, and an electrode layer formed on a surface of the current collector and having cations stored therein. In at least a part of the electrode layer, a value of ratio I a /I b of peak value I a indicating a presence of an anion decomposition compound and peak value I b indicating a presence of an electrolyte in a spectrum of an atom forming the anion is 0.45 or more and less than 2.55 as measured using X-ray photoelectron spectroscopy.

Electrode for electrochemical capacitor and electrochemical capacitor using same

An electrical storage unit includes an electrical storage section whose collector-exposed portion formed on both ends of an element is attached to a terminal plate or an outer case, and a pair of cooling plates making contact with an outer surface of the terminal plate or an outer bottom face of the outer case of the electrical storage section. This enables heat release from the electrical storage section to the cooling plate via a material with high heat conductivity, such as a metal member. Accordingly, the electrical storage section heated in charge and discharge cycles can be efficiently cooled.

Susumu Nomoto

Papers

Advanced capacitors and their application

Electric double layer capacitor and manufacture thereof

Activated carbon for use in electric double layer capacitor and method of producing the same

Electrode for electrochemical capacitor and electrochemical capacitor using same

Electrical storage unit