Structural water and disordered structure promote aqueous sodium-ion energy storage in sodium-birnessite.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31672984.
- Also identified by DOI 10.1038/s41467-019-12939-3 and PMC identifier 6823464.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Birnessite is a low-cost and environmentally friendly layered material for aqueous electrochemical energy storage; however, its storage capacity is poor due to its narrow potential window in aqueous electrolyte and low redox activity. Herein we report a sodium rich disordered birnessite (Na<sub>0.27</sub>MnO<sub>2</sub>) for aqueous sodium-ion electrochemical storage with a much-enhanced capacity and cycling life (83 mAh g<sup>-1</sup> after 5000 cycles in full-cell). Neutron total scattering and in situ X-ray diffraction measurements show that both structural water and the Na-rich disordered structure contribute to the improved electrochemical performance of current cathode material. Particularly, the co-deintercalation of the hydrated water and sodium-ion during the high potential charging process results in the shrinkage of interlayer distance and thus stabilizes the layered structure. Our results provide a genuine insight into how structural disordering and structural water improve sodium-ion storage in a layered electrode and open up an exciting direction for improving aqueous batteries.