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Scientific article
English

Enhanced Room-Temperature Ionic Conductivity of NaCB 11 H 12 via High-Energy Mechanical Milling

Published inACS applied materials & interfaces, vol. 13, no. 51, p. 61346-61356
Publication date2021-12-20
First online date2021-12-20
Abstract

The body-centered cubic (bcc) polymorph of NaCB11H12 has been stabilized at room temperature by highenergy mechanical milling. Temperature-dependent electrochemical impedance spectroscopy shows an optimum at 45-min milling time, leading to an rt conductivity of 4 mS cm−1. Mechanical milling suppresses an order−disorder phase transition in the investigated temperature range. Nevertheless, two main regimes can be identified, with two clearly distinct activation energies. Powder X-ray diffraction and 23Na solid-state NMR reveal two different Na+ environments, which are partially occupied, in the bcc polymorph. The increased number of available sodium sites w.r.t. ccp polymorph raises the configurational entropy of the bcc phase, contributing to a higher ionic conductivity. Mechanical treatment does not alter the oxidative stability of NaCB11H12. Electrochemical test on a symmetric cell (Na|NaCB11H12|Na) without control of the stack pressure provides a critical current density of 0.12 mA cm−2, able to fully charge/discharge a 120 mA h g−1 specific capacity positive electrode at the rate of C/2.

eng
Keywords
  • Na+ superionic conductor
  • NaCB11H12
  • Boron chemistry
  • Hydroborate
  • Mechanical milling
  • Solid electrolyte
Research group
Citation (ISO format)
MURGIA, Fabrizio et al. Enhanced Room-Temperature Ionic Conductivity of NaCB<sub> 11</sub> H<sub> 12</sub> via High-Energy Mechanical Milling. In: ACS applied materials & interfaces, 2021, vol. 13, n° 51, p. 61346–61356. doi: 10.1021/acsami.1c21113
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ISSN of the journal1944-8244
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Creation01/11/2022 2:31:00 PM
First validation01/11/2022 2:31:00 PM
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