Next-generation lithium-battery cathodes often involve the growth of lithium-rich phases, which enable specific capacities that are 2−3 times higher than insertion cathode materials, such as lithium cobalt oxide. Here, we investigated battery chemistry previously deemed irreversible in which lithium oxide, a lithium-rich phase, grows through the reduction of the nitrate anion in a lithium nitrate-based molten salt at 150 °C. Using a suite of independent characterization techniques, we demonstrated that a Ni nanoparticle catalyst enables the reversible growth and dissolution of micrometre-sized lithium oxide crystals through the effective catalysis of nitrate reduction and nitrite oxidation, which results in high cathode areal capacities (~12 mAh cm–2). These results enable a rechargeable battery system that has a full-cell theoretical specific energy of 1,579 Wh kg–1, in which a molten nitrate salt serves as both an active material and the electrolyte.
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The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.
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We thank C. Garland for assistance with the TEM operation, N. Dalleska and the Environmental Analysis Center of the California Institute of Technology for assistance with the ion exchange chromatography, K. Narita for assistance collecting Raman spectra and the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology for use of their XPS. This work was supported by the FY 2014 Vehicle Technologies Program Wide Funding Opportunity Announcement, under Award no. DE-FOA-0000991 (0991–1872), by the US Department of Energy (DOE) and National Energy Technology Laboratory (NETL) on behalf of the Office of Energy Efficiency and Renewable Energy (EERE).
D.A., G.V.C., V.G. and J.U. are inventors on US patent application 2016/0204418.
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