Thermally Aged Li-Mn-O Cathode with Stabilized Hybrid Cation and Anion Redox.
basic_science · Level V
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- Record sourced from PubMed, PMID 33988361.
- Also identified by DOI 10.1021/acs.nanolett.0c04920.
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Abstract
Though low-cost and environmentally friendly, Li-Mn-O cathodes suffer from low energy density. Although synthesized Li<sub>4</sub>Mn<sub>5</sub>O<sub>12</sub>-like overlithiated spinel cathode with reversible hybrid anion- and cation-redox (HACR) activities has a high initial capacity, it degrades rapidly due to oxygen loss and side-reaction-induced electrolyte decomposition. Herein, we develop a two-step heat treatment to promote local decomposition as Li<sub>4</sub>Mn<sub>5</sub>O<sub>12</sub> → 2LiMn<sub>2</sub>O<sub>4</sub> + Li<sub>2</sub>MnO<sub>3</sub> + 1/2 O<sub>2</sub>↑, which releases near-surface reactive oxygen that is harmful to cycling stability. The produced nanocomposite delivers a high discharge capacity of 225 mAh/g and energy density of over 700 Wh/kg at active-material level at a current density of 100 mA/g between 1.8 to 4.7 V. Benefiting from suppressed oxygen loss and side reactions, 80% capacity retention is achieved after 214 cycles in half cells. With industrially acceptable electrolyte amount (6 g/Ah), full cells paired with Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub> anode have a good retention over 100 cycles.