Huang Zi-Hang, Li Hao, Li Wen-Han, Henkelman Graeme, Jia Baohua, Ma Tianyi
Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang, 110036, China.
Department of Chemistry, The Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, TX, 78712, USA.
Small. 2020 Dec 2:e2004709. doi: 10.1002/smll.202004709.
Intrinsic defects, including oxygen vacancies, can efficiently modify the electrochemical performance of metal oxides. There is, however, a limited understanding of how vacancies influence charge storage properties. Here, using tungsten oxide as a model system, an extensive study of the effects of structure, electrical properties, and charge storage properties of oxygen vacancies is carried out using both experimental and computational techniques. The results provide direct evidence that oxygen vacancies increase the interlayer spacing in the oxide, which suppress the structural pulverization of the material during electrolyte ion insertion and removal in prolonged stability tests. Specifically, no capacitive decay is detected after 30 000 cycles. The medium states and charge storage mechanism of oxygen-deficient tungsten oxide throughout electrochemical charging/discharging processes is studied. The enhanced rate capability of the oxygen-deficient WO is attributed to improved charge storage kinetics in the bulk material. The WO electrode exhibits the highest capacitance in reported tungsten-oxide based electrodes with comparable mass loadings. The capability to improve electrochemical capacitance performance of redox-active materials is expected to open up new opportunities for ultrafast supercapacitive electrodes.
包括氧空位在内的本征缺陷能够有效改变金属氧化物的电化学性能。然而，对于空位如何影响电荷存储性能的理解仍然有限。在此，以氧化钨作为模型体系，运用实验和计算技术对氧空位的结构、电学性能及电荷存储性能的影响展开了广泛研究。结果提供了直接证据，表明氧空位增加了氧化物中的层间距，这在长时间稳定性测试中抑制了材料在电解质离子嵌入和脱出过程中的结构粉化。具体而言，在30000次循环后未检测到电容衰减。研究了缺氧氧化钨在整个电化学充放电过程中的中间状态和电荷存储机制。缺氧WO的倍率性能增强归因于块状材料中电荷存储动力学的改善。在具有可比质量负载的已报道氧化钨基电极中，WO电极展现出最高的电容。氧化还原活性材料改善电化学电容性能的能力有望为超快超级电容电极带来新机遇。
