Entropy-increased LiMn<sub>2</sub>O<sub>4</sub>-based positive electrodes for fast-charging lithium metal batteries.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39191739.
- Also identified by DOI 10.1038/s41467-024-51168-1 and PMC identifier 11349939.
- Licence recorded as CC BY-NC-ND.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Fast-charging, non-aqueous lithium-based batteries are desired for practical applications. In this regard, LiMn<sub>2</sub>O<sub>4</sub> is considered an appealing positive electrode active material because of its favourable ionic diffusivity due to the presence of three-dimensional Li-ion diffusion channels. However, LiMn<sub>2</sub>O<sub>4</sub> exhibits inadequate rate capabilities and rapid structural degradation at high currents. To circumvent these issues, here we introduce quintuple low-valence cations to increase the entropy of LiMn<sub>2</sub>O<sub>4</sub>. As a result, the entropy-increased LiMn<sub>2</sub>O<sub>4</sub>-based material, i.e., LiMn<sub>1.9</sub>Cu<sub>0.02</sub>Mg<sub>0.02</sub>Fe<sub>0.02</sub>Zn<sub>0.02</sub>Ni<sub>0.02</sub>O<sub>4</sub>, when tested in non-aqueous lithium metal coin cell configuration, enable 1000 cell cycles at 1.48 A g<sup>-1</sup> (corresponding to a cell charging time of 4 minutes) and 25°C with a discharge capacity retention of about 80%. We demonstrate that the increased entropy in LiMn<sub>2</sub>O<sub>4</sub> leads to an increase in the disordering of dopant cations and a contracted local structure, where the enlarged LiO<sub>4</sub> space and enhanced Mn-O covalency improve the Li-ion transport and stabilize the diffusion channels. We also prove that stress caused by cycling at a high cell state of charge is relieved through elastic deformation via a solid-solution transition, thus avoiding structural degradation upon prolonged cycling.