Intercalation-Induced Conversion Reactions Give High-Capacity Potassium Storage.
basic_science · Level V
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- Record sourced from PubMed, PMID 33016705.
- Also identified by DOI 10.1021/acsnano.0c06606.
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Abstract
Potassium ion batteries (PIBs) have shown great potential as a next-generation electrochemical energy storage system, due to the natural abundance of potassium and the relatively low redox potential of K ions. To accommodate the large ionic radius of K ions, conversion-type electrode materials are regarded as suitable candidates for K ion storage. However, the triggering mechanism of a conversion reaction in most anode materials of PIBs is unclear, which limits their further development. To reveal the mechanism, in this work, MoSe<sub>2</sub>, MoS<sub>2</sub>, and MoO<sub>2</sub> were selected as model materials, guided by theoretical calculations, to investigate the K ion storage process. Through <i>ex situ</i> characterization, it was found that intercalation reactions preferentially occur in MoSe<sub>2</sub> and MoS<sub>2</sub>, while an adsorption reaction preferentially occurs in MoO<sub>2</sub>. This is because of the larger interlayer spacing and lower K ion intercalation barrier in MoSe<sub>2</sub> and MoS<sub>2</sub> than in MoO<sub>2</sub>. The preferential intercalation reactions are able to induce a further conversion reaction by reducing the reaction barrier, thereby realizing high K ion storage capacities. As a result, the MoSe<sub>2</sub>-rGO and MoS<sub>2</sub>-rGO hybrids showed higher reversible capacities than the MoO<sub>2</sub>-rGO hybrid. By demonstrating a relationship between intercalation and the conversion reaction and understanding the mechanism, guidance is provided for selecting the electrode materials to obtain PIBs with high performance.