@article{34065,
  author = {Haegyeom Kim and Dong-Hwa Seo and Alexander Urban and Jinhyuk Lee and Deok-Hwang Kwon and Shou-Hang Bo and Tan Shi and Joseph K Papp and Bryan D McCloskey and Gerbrand Ceder},
  title = {Stoichiometric Layered Potassium Transition Metal Oxide for Rechargeable Potassium BatteriesStoichiometric Layered Potassium Transition Metal Oxide for Rechargeable Potassium Batteries},
  abstract = {<p>K-ion batteries are promising alternative energy storage systems for large-scale applications because of the globally abundant K reserves. K-ion batteries benefit from the lower standard redox potential of K/K<sup>+</sup> than that of Na/Na<sup>+</sup> and even Li/Li<sup>+</sup>, which can translate into a higher working voltage. Stable KC<sub>8</sub> can also be formed via K intercalation into a graphite anode, which contrasts with the thermodynamically unfavorable Na intercalation into graphite, making graphite a readily available anode for K-ion battery technology. However, to construct practical rocking-chair K-ion batteries, an appropriate cathode material that can accommodate reversible K release and storage is still needed. We show that stoichiometric KCrO<sub>2</sub> with a layered O3-type structure can function as a cathode for K-ion batteries and demonstrate a practical rocking-chair K-ion battery. In situ X-ray diffraction and electrochemical titration demonstrate that K<sub><em>x</em></sub>CrO<sub>2</sub> is stable for a wide K content, allowing for topotactic K extraction and reinsertion. We further explain why stoichiometric KCrO<sub>2</sub> is unique in forming the layered structure unlike other stoichiometric K-transition metal oxide compounds, which form nonlayered structures; this fundamental understanding provides insight for the future design of other layered cathodes for K-ion batteries.</p>},
  year = {2018},
  journal = {Chemistry of Materials},
  volume = {30},
  pages = {6532 - 6539},
  month = {08/2018},
  issn = {0897-4756},
  url = {https://pubs.acs.org/doi/10.1021/acs.chemmater.8b03228https://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.8b03228https://pubs.acs.org/doi/suppl/10.1021/acs.chemmater.8b03228/suppl_file/cm8b03228_si_001.pdf},
  doi = {10.1021/acs.chemmater.8b03228},
  language = {eng},
}