Origins of Boosted Charge Storage on Heteroatom‐Doped Carbons

Abstract

Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons,n one of the present studies has shown aw hole landscape.H erein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in ab roadened operating voltage,but also successfully promotes the specific capacitance in aqueous supercapacitors.I np articular,t he electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, ak ey step of water decomposition during the charging process,w hich broadens the voltage windowo fa queous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore,t he reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatomdoped carbon surface,t hus yielding ab oosted charge storage performance.

Perspective on High‐Energy Carbon‐Based Supercapacitors

“…Using density functional theory calculations, they proposed that such phosphorus-enriched carbon with the minimum adsorption energy promotes more electrolyte cations to adsorb on the carbon surface, which suppresses hydrogen evolution reaction and thus is responsible for the widened potential window. [119] Sulfur doping at the edge or near defects of carbon materials typically forms C-S bonds including Sp3/2, Sp1/2, and C-SOx-C states. Although the electronegativity of sulfur is similar to carbon, the presence of sulfur on carbon surface can modify the bond lengths and bond angles, and spin densities, thus providing the redox-active sites for pseudocapacitance.…”

Recent advances in carbon-based supercapacitors

“…Alternative carbon precursors encompass conventional biomasses and phenolic resins as well as novel organic salts/polymers such as metal salts, metal-organic frameworks (MOFs), covalent organic frameworks, conjugated microporous polymers, hypercrosslinked polymers, ionic liquids and poly(ionic liquid)s, etc. [13][14][15][16] High flexibility in the precursor choice and condition regulation can customize ideal porous carbon electrodes with the following structural superiorities: (a) large surface area to guarantee a vast accumulation platform for high energy storage, coupled with abundant adsorbing sites exposed on the surface topography to improve the accessible surface area; 17,18 (b) tunable pore structures to ensure the rapid transmission of electrolyte ions and continuous infiltration into the electrode surface, thereby enabling higher power delivery; 11,19,20 (c) surface wettability/activity to boost the electrolyte/electrode interfacial contact and afford more active sites for improved charge accumulation and ion kinetics; [21][22][23] and (d) stable conductive frameworks for long-term operation. 7,24,25 In the following sections, we focus on the recent advances in the two core components (i.e., electrodes and electrolytes) of CSs.…”

“…22,120 Firstly, binding heterogeneous atoms into the carbon backbone induces positive partial charges on the neighboring carbon atoms/heteroatoms with lower electronegativity to present a polarized electrode surface, and therefore, these polarized sites enhance the interactions with electrolyte ions to facilitate adsorption. 20,23 Secondly, the substitutive incorporation of electron-donor heteroatoms supplements the lone pair of electrons to the delocalized carbon framework for improved intrinsic conductivity, and the decreased valence band contributes toward the long-term running and high electron density at the Fermi level. 25 Thirdly, the embedment of pseudo-active heteroatoms can facilitate proton adsorption and endow bare carbons with remarkable faradaic pseudocapacitance based on electrochemical redox reactions.…”

Rapid and Controllable Synthesis of Nanocrystallized Nickel‐Cobalt Boride Electrode Materials via a Mircoimpinging Stream Reaction for High Performance Supercapacitors

“…[1][2][3][4] However, the low energy density of commercial supercapacitors has impeded their applications in energy storage devices. For this reason, many battery-type "pseudocapacitors" have been developed with the aim of boosting energy densities, including such as heteroatom-doped carbon, [5][6][7] transition metal compounds, [8][9][10] and their hybrids. [11,12] Recently, intensive research works have been focused on the studies of transition metal oxides and hydroxides as ideal pseudocapacitive materials [13][14][15][16][17] for supercapacitors, due to their large theoretical capacitances.…”