A team of researchers in Japan, including colleagues from the R&D Center at batter-maker GS Yuasa, are exploring Li3NbO4-based (trilithium niobate) materials as new and promising electrode materials for high-energy rechargeable lithium batteries. A paper on their work is published in Proceedings of the National Academy of Sciences (PNAS).
Herein, as a compound with further excess lithium contents, a cation-ordered rocksalt phase with lithium and pentavalent niobium ions, Li3NbO4, is first examined as the host structure of a new series of high-capacity positive electrode materials for rechargeable lithium batteries.
Approximately 300 mAh⋅g−1 of high-reversible capacity at 50 °C is experimentally observed, which partly originates from charge compensation by solid-state redox of oxide ions. It is proposed that such a charge compensation process by oxide ions is effectively stabilized by the presence of electrochemically inactive niobium ions. These results will contribute to the development of a new class of high-capacity electrode materials, potentially with further lithium enrichment (and fewer transition metals) in the close-packed framework structure with oxide ions.—Yabuuchi et al.
The lithium ions quickly migrate in percolative network in bulk without a sacrifice in kinetics. A large reversible capacity originates from the participation of oxide ions for a charge compensation process, the researchers said.
This finding can be further expanded to the design of innovative positive electrode materials beyond the restriction of the solid-state redox reaction based on the transition metals used for the past three decades.—Yabuuchi et al.
Naoaki Yabuuchi, Mitsue Takeuchi, Masanobu Nakayama, Hiromasa Shiiba, Masahiro Ogawa, Keisuke Nakayama, Toshiaki Ohta, Daisuke Endo, Tetsuya Ozaki, Tokuo Inamasu, Kei Sato, and Shinichi Komaba (2015) “High-capacity electrode materials for rechargeable lithium batteries: Li3NbO4-based system with cation-disordered rocksalt structure” PNAS 112 (25) 7650-7655 doi: 10.1073/pnas.1504901112
Victoria L. McLaren, Caroline A. Kirk, Martha Poisot, Maria Castellanos and Anthony R. West (2004) “Li+ ion conductivity in rock salt-structured nickel-doped Li3NbO4” Dalton Trans. 3042-3047 doi: 10.1039/B316396M
Toetsu Shishido, Hiroe Suzuki, Kazutoshi Ukei, Taketoshi Hibiya, Tsuguo Fukuda (1996) “Flux growth and crystal structure determination of trilithium niobate,” Journal of Alloys and Compounds, Volume 234, Issue 2, Pages 256-259 doi: 10.1016/0925-8388(95)02123-X