Solubility contrast strategy for enhancing intercalation pseudocapacitance in layered MnO2 electrodes
| Autor: | Nirpendra Singh, Chuan Xia, Yongjiu Lei, Husam N. Alshareef, Yun-Pei Zhu, Udo Schwingenschlögl |
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| Rok vydání: | 2019 |
| Předmět: |
Birnessite
Nanostructure Materials science Renewable Energy Sustainability and the Environment Coprecipitation Intercalation (chemistry) 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Redox Pseudocapacitance 0104 chemical sciences Chemical engineering General Materials Science Crystallite Electrical and Electronic Engineering Solubility 0210 nano-technology |
| Zdroj: | Nano Energy. 56:357-364 |
| ISSN: | 2211-2855 |
| DOI: | 10.1016/j.nanoen.2018.11.063 |
| Popis: | Pseudocapacitance is generally associated with either surface redox reactions or ion intercalation processes without a phase transition. Typically, these two mechanisms have been independently studied, and most works have focused on optimizing one or the other in different material systems. Here we have developed a strategy based on solubility contrast, in which the contribution from the two capacitive mechanisms is simultaneously optimized. Taking layered birnessite MnO2 as a model, controllable nanostructures and oxygen vacancies are achieved through a simple coprecipitation process. Simultaneously controlling crystallite size and defect concentration is shown to enhance the charging-discharging kinetics together with both redox and intercalation capacitances. This synergistic effect results from enhanced ionic diffusion, electronic conductivity, and large surface-to-volume ratio. In addition, considerable cycling durability is achieved, resulting from improved framework strength by defect creation and the absence of proton (de)intercalation during discharge/charge. This work underscores the importance of synergistically regulating nanostructure and defects in redox-active materials to improve pseudocapacitive charge storage. |
| Databáze: | OpenAIRE |
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