Enhanced Ionic Conductivity and Electrochemical Properties of Li2B12H12/ZrO2 Nanocomposites for All-Solid-State Lithium Metal Batteries

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Abstract
Solid-state electrolytes play a key role in the development of safe and high-capacity all-solid-state batteries. Complex hydrides such as Li2B12H12 are attractive as solid electrolytes due to their low weight and good electrochemical stability, but suffer from low conductivities at room temperature. Herein, we report a three-order-magnitude increase in the ionic conductivity of Li2B12H12 upon nanocomposite formation with ZrO2 via mechanochemical treatment, reaching 2.9 × 10-4 S cm-1 at 30 °C. Results from infrared spectroscopy, X-ray Raman scattering and electron microscopy coupled with electron energy loss spectroscopy suggest that the increased ionic conductivity is due to strong interfacial interaction/reaction between Li2B12H12 and ZrO2. This leads to a highly defective interphase region where the Li, B, Zr, and O chemical environments are distinctively different from the bulk Li2B12H12 and ZrO2. The improved ionic conductivity of the nanocomposite compared to the pristine material enabled the realization of all-solid-state batteries with a Li metal anode and both TiS2 and LiFePO4 cathodes. We demonstrate the suitability of the nanocomposite at various charging rates up to C/2 (0.34 mA cm-2) for over 170 cycles at 40-60 °C (Li|Li2B12H12/ZrO2|TiS2).
Funding Information
  • H2020 Marie Sklodowska-Curie Actions (860553)
  • Nederlandse Organisatie voor Wetenschappelijk Onderzoek
  • BatteryNL – Next Generation Batteries based on Understanding Materials Interfaces (NWA.1389.20.089)
  • Netherlands Electron Microscopy Infrastructure (184.034.014)

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