Li₃Mo₄P₅O₂₄: A two-electron cathode for lithium-ion batteries with three-dimensional diffusion pathways

Journal Article · Sat Mar 05 00:00:00 EST 2016 · Chemistry of Materials

DOI:https://doi.org/10.1021/acs.chemmater.6b00177· OSTI ID:1257965

Wen, Bohua ^[1]; Khalifah, Peter G. ^[2]; Liu, Jue ^[2]; Chernova, Natasha A. ^[1]; Wang, Xiaoya ^[1]; Janssen, Yuri ^[3]; Omenya, Fredrick ^[1]; Whittingham, M. Stanley ^[1]

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1. State Univ. of New York at Binghamton, Binghamton, NY (United States)
2. State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
3. State Univ. of New York at Stony Brook, Stony Brook, NY (United States)

The structure of the novel compound Li₃Mo₄P₅O₂₄ has been solved from single crystal X-ray diffraction data. The Mo cations in Li₃Mo₄P₅O₂₄ are present in four distinct types of MoO₆ octahedra, each of which has one open vertex at the corner participating in a Mo=O double bond and whose other five corners are shared with PO₄ tetrahedra. On the basis of a bond valence sum difference map (BVS-DM) analysis, this framework is predicted to support the facile diffusion of Li⁺ ions, a hypothesis that is confirmed by electrochemical testing data, which show that Li₃Mo₄P₅O₂₄ can be utilized as a rechargeable battery cathode material. It is found that Li can both be removed from and inserted into Li₃Mo₄P₅O₂₄. The involvement of multiple redox processes occurring at the same Mo site is reflected in electrochemical plateaus around 3.8 V associated with the Mo⁶⁺/Mo⁵⁺ redox couple and 2.2 V associated with the Mo⁵⁺/Mo⁴⁺ redox couple. The two-electron redox properties of Mo cations in this structure lead to a theoretical capacity of 198 mAh/g. When cycled between 2.0 and 4.3 V versus Li⁺/Li, an initial capacity of 113 mAh/g is observed with 80% of this capacity retained over the first 20 cycles. Lastly, this compound therefore represents a rare example of a solid state cathode able to support two-electron redox capacity and provides important general insights about pathways for designing next-generation cathodes with enhanced specific capacities.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States); Energy Frontier Research Centers (EFRC) (United States). Northeastern Center for Chemical Energy Storage (NECCES)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012704; SC0001294
• OSTI ID: 1257965
• Report Number(s): BNL-112314-2016-JA; R&D Project: CO009; KC0302010
• Journal Information: Chemistry of Materials, Vol. 28, Issue 7; ISSN 0897-4756
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY