Abstract
The polymorphs of MnO2 attract great deal of attention as electrode materials due to their layer/ tunnel structures which allow for rapid intercalation/deintercalation and facilitate fast charge–discharge. Pre-intercalating MnO2 with alkali cations is reported to enhance ion diffusion yielding better electrochemical response. Taking advantage of crystal structure of MnO2 and intercalated K+-ions, a facile synthesis of cauliflower-shaped MnO2 nanoparticles that yields self-intercalation of K+ ions is reported. Controlled sample is obtained by thoroughly washing as-prepared sample and their electrochemical response for Na-ion pseudocapacitors is compared. The sample with K+ exhibits ∼20 % enhancement in specific capacitance value. Both the samples yield better electrochemical properties in basic electrolyte (NaOH) as compared to neutral electrolyte (NaNO3). The asymmetric device fabricated using MnO2-K as the positive electrode and activated carbon (AC) as the negative electrode yields an impressive energy density of ̴ 23 Wh kg−1 with the cycling stability of 98 % after 1000 cycles.
Published Version
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