Transition‐Metal Oxynitride: A Facile Strategy for Improving Electrochemical Capacitor Storage

Abstract

The use of transition‐metal oxide (TMO) as an extended‐life electrochemical energy storage material remains challenging because TMO undergoes volume expansion during energy storage. In this work, a transition‐metal oxynitride layer (TMON, M: Fe, Co, Ni, and V) was synthesized on TMO nanowires to address the crucial issue of volume expansion. The unique oxynitride layer possesses numerous active sites, excellent conductivity, and outstanding stability. These characteristics enhance specific capacitance and alleviate volume expansion effectively. Specifically, the specific capacity of the TMON electrode is enhanced by approximately twofold relative to that of its corresponding oxide. Notably, the capacitance of the TMON remains above 94% even after 10 000 cycles. This result indicates that the cycling performance of the TMON electrode is superior to that of its corresponding oxide. First‐principles and quantitative kinetics analyses are performed to investigate the mechanism underlying the improved electrochemical performances of the TMON layers. Results demonstrate that the proposed TMON layer has attractive applications in the fields of energy storage, conversion, and beyond.

Redox Tuning in Crystalline and Electronic Structure of Bimetal–Organic Frameworks Derived Cobalt/Nickel Boride/Sulfide for Boosted Faradaic Capacitance

“…Extensive energy demands by portable electronics and electric vehicles have indorsed the rapid development of highly efficient energy storage technologies for human society . Electrochemical capacitors (ECs) have received significant attention as a strong candidate in virtue of high power density, fast charging rate, and long‐term cyclability . Since the performance metrics and energy storage mechanism of ECs depend on the electrode materials, extensive investigations have been performed to optimize the structure and electronic valence of inorganic materials to improve the energy density …”

Miniaturized Energy Storage Devices Based on Two‐Dimensional Materials

“…Layered TMOs (typically Fe, Co, Ni, Mn, or V compounds) also can be exfoliated into 2D nanosheets, and thus, have attracted intense interest in electrochemical energy storage research because of their high specific capacity, facile synthetic strategies, abundant reserves, adjustable material structures, and so forth. However, TMO materials suffer from poor electrical conductivity and large volume changes in energy storage, which usually lead to rapid capacity decays . A recognized strategy for increasing the electrical conductivity of TMOs is to combine them with highly conductive materials, such as CNTs, graphene, and conducting polymers.…”

“…However,T MO materials suffer from poor electrical conductivity and large volumec hanges in energy storage, which usually lead to rapid capacityd ecays. [137][138][139] Ar ecognized strategy for increasing the electrical conductivity of TMOs is to combine them with highly conductive materials, such as CNTs, graphene,a nd conducting polymers. Additionally,m any other methods, including the introduction of defects( holes or vacan-cies), doping with metallicc omponents, and incorporation into ac onductive matrix, can be also effective at realizing better electrochemical performances for TMOs.…”

Heterocarbides Reinforced Electrochemical Energy Storage

“…In addition, Mo–C (MoC, 282.9 eV) and Mo–C (Mo 2 C, 283.7 eV) bonds were individually observed in the MoC‐nws and Mo 2 C‐nws samples, respectively, and signals at 282.9/283.7 eV were both observed in MoC‐Mo 2 C‐hnws. The above results demonstrate that these samples contain different Mo–C bonding modes and Mo chemical states, which may result in distinct electronic states and associated divergent anodic performances of the samples …”

“…In comparison, aside from some oxidation peaks, only the distinctive Mo 3+ peak could be detected in MoC‐nws, and Mo 2+ species in Mo 2 C‐nws, respectively. It is known that conversion reaction based materials with lightweight and additional metal cation valences are beneficial for raising the theoretical capacity for lithium storage . In addition to this, rich interfaces in nanoelectrodes could contribute to facilitating mass transport process and redox reversibility because of the significantly reduced diffusion distances of charge carriers .…”