Rechargeable-battery chemistry based on lithium oxide growth through nitrate anion redox

Abstract

Next-generation lithium-battery cathodes often involve the growth of lithium-rich phases, which enables specific capacities that 2-3 times higher than insertion cathode materials such as lithium cobalt oxide (LiCoO 2). Here, we investigate battery chemistry previously deemed irreversible in which lithium oxide (Li 2 O), a lithium-rich phase, grows through reduction of the nitrate anion in a lithium nitrate-based molten salt at 150 °C. Using a suite of independent characterization techniques, we demonstrate that a Ni nanoparticle catalyst enables the reversible growth and dissolution of micron-sized Li 2 O crystals through the effective catalysis of nitrate reduction and nitrite oxidation, resulting 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 1579 Wh/kg, in which a molten nitrate salt serves as both active material and electrolyte.

Designing electrolytes with polymerlike glass-forming properties and fast ion transport at low temperatures

“…It is commonly assumed that the beneficial effects of LiNO 3 come mostly from its role in regulating chemistry and transport properties of interphases formed on the Li electrode. Various literature has also explained the beneficial effects of LiNO 3 in terms of its influence on Li surface chemistry and solvation of intermediates formed at Li electrodes in liquid electrolytes (14,29,(36)(37)(38). Because Li already exhibits exceptional reversibility in the DOL electrolyte, we hypothesized that these electrolytes would provide a good testbed for understanding how LiNO 3 works.…”

Enhanced ion transport in Li2O and Li2S films

“…They typically form as part of a solidelectrolyte interphase (SEI) passivation layer when a low-voltage anode reduces an electrolyte that contains the elements oxygen or sulfur. [1][2][3] They are also an important reaction product in conversion electrodes based on oxides, 4 oxygen, 5 nitrates, 6 sulfides, 4 sulfur, 7 and so on. The solid-state ion transport rates within the Li 2 O and Li 2 S can limit battery performance, yet the rates are not well-understood, partly because many phases are involved.…”

First-Principles Computational and Experimental Investigation of Molten-Salt Electrolytes: Implications for Li–O2 Battery

“…Prior studies in primary thermal batteries have reported NO 3 – → NO 2 – nitrate to nitrite reduction driven by catalytic electrodes. , Using Ni nanoparticles as catalytic cathodes, Giordani et al. have demonstrated a rechargeable electrochemistry with the main deposition product as Li 2 O. The grand potential analysis currently does not capture the NO 3 – → NO 2 – nitrate to nitrite reduction.…”