Solubility Contrast Strategy for Enhancing Intercalation Pseudocapacitance in Layered MnO2 Electrodes

Yun-Pei Zhu, Chuan Xia, Yongjiu Lei, Nirpendra Singh, Udo Schwingenschlögl, Husam N. Alshareef

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

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 pseudocapative charge storage.
Original languageEnglish (US)
Pages (from-to)357-364
Number of pages8
JournalNano Energy
Volume56
DOIs
StatePublished - Nov 24 2018

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