Titanium Disulfide Coated Carbon Nanotube Hybrid Electrodes Enable High Energy Density Symmetric Pseudocapacitors

Abstract

While electrochemical supercapacitors often show high power density and long operation lifetimes, they are plagued by limited energy density. Pseudocapacitive materials, in contrast, operate by fast surface redox reactions and are shown to enhance energy storage of supercapacitors. Furthermore, several reported systems exhibit high capacitance but restricted electrochemical voltage windows, usually no more than 1 V in aqueous electrolytes. Here, it is demonstrated that vertically aligned carbon nanotubes (VACNTs) with uniformly coated, pseudocapacitive titanium disulfide (TiS ) composite electrodes can extend the stable working range to over 3 V to achieve a high capacitance of 195 F g in an Li-rich electrolyte. A symmetric cell demonstrates an energy density of 60.9 Wh kg -the highest among symmetric pseudocapacitors using metal oxides, conducting polymers, 2D transition metal carbides (MXene), and other transition metal dichalcogenides. Nanostructures prepared by an atomic layer deposition/sulfurization process facilitate ion transportation and surface reactions to result in a high power density of 1250 W kg with stable operation over 10 000 cycles. A flexible solid-state supercapacitor prepared by transferring the TiS -VACNT composite film onto Kapton tape is demonstrated to power a 2.2 V light emitting diode (LED) for 1 min.

Experimental and Theoretical Investigation of the Effect of Oxygen Vacancies on the Electronic Structure and Pseudocapacitance of MnO2

“…Generally,s upercapacitors can be divided into two types of systems according to the different charges toragep rinciples. [4,5] Electrochemicald ouble-layer capacitors (EDLCs) store the charge by formingadouble layer of opposing ions, [6,7] generally employing graphene, [8] carbon nanotubes [9,10] or activated carbon [11] as electrodes. Another type is pseudocapacitors, which can be used to achievee nergy storaget hrough Faraday charget rans-fer;t he electrode materials are usually formed from conducting polymers and transition metal oxides/hydroxides, such as NiO, [12,13] MnO 2 , [14] Co 3 O 4 , [15] MoS 2 , [3] andN i(OH) 2.…”

Sandwich‐Like Ultrathin TiS2 Nanosheets Confined within N, S Codoped Porous Carbon as an Effective Polysulfide Promoter in Lithium‐Sulfur Batteries

“…XPS was carried out to investigate the elemental bonding configurations of the as-prepared TiS 2 @NSC. [29] The peaks at the binding energies of 163.6, 164.8, and 168.8 eV in the high-resolution S 2p spectrum indicate the presence of Ti-S and S-O covalent bonds ( Figure S4c, Supporting Information). The high resolution Ti 2p XPS spectrum exhibits two peaks at 458.7 and 464.3 eV, which can be ascribed to Ti 4+ 2p3/2 and Ti 4+ 2p1/2, respectively ( Figure S4b, Supporting Information).…”

Aqueous Symmetric Supercapacitors with Carbon Nanorod Electrodes and Water‐in‐Salt Electrolyte

“…Increasing the amount pores and adjusting the pore size are effective strategies to increase the surface area of electrode materials . Although the introduction of pseudocapacitive reaction in supercapacitors can improve the capacitance of the electrode materials, it will certainly sacrifice the intrinsic characteristics of fast charge ability, high output power and superior cyclic stability of EDLCs . Among the electrode materials for EDLCs, porous activated carbon is one of the most promising and typical electrode materials because of their advantages of excellent conductivity, high specific surface area, easy availability and low cost .…”