Oxygen vacancies refilling and potassium ions intercalation of δ-manganese dioxide with high structural stability toward 2.3 V high voltage asymmetric supercapacitors

Jingli Zhao; Xuesong Liu; Peng Liu; Kuan Deng; Xingbin Lv; Wen Tian; Caihong Wang; Shuai Tan; Junyi Ji

doi:10.1016/j.jcis.2022.09.119

Oxygen vacancies refilling and potassium ions intercalation of δ-manganese dioxide with high structural stability toward 2.3 V high voltage asymmetric supercapacitors

J Colloid Interface Sci. 2023 Jan;629(Pt B):1039-1048. doi: 10.1016/j.jcis.2022.09.119. Epub 2022 Sep 27.

Authors

Jingli Zhao¹, Xuesong Liu¹, Peng Liu¹, Kuan Deng¹, Xingbin Lv², Wen Tian¹, Caihong Wang¹, Shuai Tan¹, Junyi Ji³

Affiliations

¹ School of Chemical Engineering, Sichuan University, Chengdu 610065, PR China.
² College of Chemistry and Environment, Southwest Minzu University, Sichuan 610041, PR China.
³ School of Chemical Engineering, Sichuan University, Chengdu 610065, PR China; State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, PR China. Electronic address: junyiji@scu.edu.cn.

PMID: 36209567
DOI: 10.1016/j.jcis.2022.09.119

Abstract

Oxygen vacancies occupation and coordination environment modulation of the transition-metal based electrodes are effective strategies to improve the structural stability and electrochemical performance. In this work, the 2-methylimidazole (2-MI) doped manganese dioxide (MnO₂) anchored on carbon cloth (CC) is fabricated via a simple method (MI-MnO_2-x/CC), where the oxygen defects on/inside the K⁺ doped δ-MnO₂ nanosheets are in-situ created by reductive ethanol/Mn²⁺ and occupied by 2-MI ligands. With the pre-embedded K⁺ ions and abundant ligand-refilled defects, the electronic coordination structure, structural stability and electron/ion diffusion efficiency can be effectively enhanced. Therefore, the MI-MnO_2-x/CC reveals a remarkable specific capacitance of 721.2 mF cm^-2 with excellent cycle durability (capacitance retention of 93.4% after 10,000 cycles) under 1.3 V operation potential window. In addition, an asymmetric supercapacitor assembled by MI-MnO_2-x/CC and activated mechanical exfoliated graphene oxide yields a maximum energy density of 57.0 Wh kg^-1 and a highest power density of 23.0 kW kg^-1 under 2.3 V. This effective oxygen defect stabilization strategy by ligands refilling can be extended to various metal oxide-based electrodes for energy storage and conversion.

Keywords: Enlarged potential window; K(+) dopant; Ligand refilling; Oxygen defects; Supercapacitor; δ-MnO(2) nanosheets.