Oxygen‐Deficient Homo‐Interface toward Exciting Boost of Pseudocapacitance

Abstract

Pseudocapacitors hold great promise as charge storage systems that combine battery‐level energy density and capacitor‐level power density. The utilization of pseudocapacitive material, however, is usually restricted to the surface due to poor electrode kinetics, leading to less accessible charge storage sites and limited capacitance. Here, tin oxide is successfully endowed with outstanding pseudocapacitance and fast electrode kinetics in a negative potential window by engineering oxygen‐deficient homo‐interfaces. The as‐prepared SnO2−x@SnO2−x electrode yields a specific capacitance of 376.6 F g−1 at the current density of 2.5 A g−1 and retains 327 F g−1 at a high current density of 80 A g−1. The theoretical calculation reveals that the oxygen defects are more favorable at homo‐interfaces than at the surface due to the lower defect formation energy. Meanwhile, as compared with the surface, the homo‐interface possesses more stable Li+ storage sites that are readily accessed by Li+ due to the occurrence of oxygen vacancies, enabling outstanding pseudocapacitance as well as high rate capability. This oxygen‐deficient homo‐interface design opens up new opportunities to develop high‐energy and power pseudocapacitors.

Encapsulating Oxygen‐Deficient TiNb24O62 Microspheres by N‐Doped Carbon Nanolayer Boosts Capacity and Stability of Lithium‐Ion Battery

“…Additionally, the N-doped carbon nanolayer prevents the direct contact between these nanoparticles and electrolyte, helping form a stable interface layer. [66] At the same time, the extra Li + can be stored in the formed oxygen deficiencies in crystals, and thus providing additional reaction sites and promoting the diffusion of Li ions. [43] Benefiting from both the oxygendeficiency of TNO and N-doped carbon coating nanolayer, the DTNO@NC realizes higher conductivity, smaller charge resistance, more reactive active sites, and stable interface structure, resulting in superior rate capability and electrochemical performance.…”

Intercalation in Two‐Dimensional Transition Metal Carbides and Nitrides (MXenes) toward Electrochemical Capacitor and Beyond

“…[1][2][3][4][5] In some high power or safety required applications, ECs show promise that can work as the supplementary of the batteries or even total substitution. [6][7][8][9][10] In the past decades, thanks to the development of materials science and advanced characterization methods, the performance of ECs has been improved significantly. [11][12][13][14] However, the performance is still not satisfying to meet the higher requirements of the next generation of portable electronics, hybrid electric vehicles, large industrial equipment, and wearable electronics.…”

Transition Bimetal Based MOF Nanosheets for Robust Aqueous Zn Battery

“…The energy density and power density are two important parameters for describing electrochemical performance of Ni,Cu-MOF//Zn battery (Wu et al, 2019;Liu et al, 2020). As revealed in Figure 6A, the as-fabricated Ni,Cu-MOF//Zn battery exhibited a maximum voluminal energy density of 71.23 mWh cm −3 at a power density of 3530.61 mW cm −3 , which outperforms most reported asymmetric supercapacitors and aqueous electrolyte-based batteries, such as hVCNT2//hVCNT2 (41 mWh cm −3 ) (Wu et al, 2016), FGN-300//FGN-300 (27.2 mWh cm −3 ) (Yan et al, 2014), SANF//Zn (15.1 mWh cm −3 ) (Wang R. et al, 2018), CNTs//Fe 3 O 4 -C (1.56 mWh cm −3 ) (Li R. et al, 2015), NiCo//Zn (8 mW h cm −3 ) (Huang et al, 2017).…”