Nanosized and metastable molybdenum oxides as negative electrode materials for durable high-energy aqueous Li-ion batteries

Jeongsik Yun; Ryota Sagehashi; Yoshihiko Sato; Takuya Masuda; Satoshi Hoshino; Hongahally Basappa Rajendra; Kazuki Okuno; Akihisa Hosoe; Aliaksandr S Bandarenka; Naoaki Yabuuchi

doi:10.1073/pnas.2024969118

Nanosized and metastable molybdenum oxides as negative electrode materials for durable high-energy aqueous Li-ion batteries

Proc Natl Acad Sci U S A. 2021 Nov 30;118(48):e2024969118. doi: 10.1073/pnas.2024969118.

Authors

Jeongsik Yun^{1

2}, Ryota Sagehashi³, Yoshihiko Sato⁴, Takuya Masuda⁵, Satoshi Hoshino³, Hongahally Basappa Rajendra⁴, Kazuki Okuno⁶, Akihisa Hosoe⁶, Aliaksandr S Bandarenka^{1

2}, Naoaki Yabuuchi^{7

8

9}

Affiliations

¹ Physics of Energy Conversion and Storage, Physik-Department, Technische Universität München, 85748 Garching, Germany.
² E-Conversion 80799 Munich, Germany.
³ Department of Applied Chemistry, Tokyo Denki University, Tokyo 120-8551, Japan.
⁴ Department of Chemistry and Life Science, Yokohama National University, Kanagawa 240-8501, Japan.
⁵ Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Ibaraki 305-0044, Japan.
⁶ Energy and Electronics Materials R&D Laboratories, Sumitomo Electric Industries, Ltd., 554-0024 Osaka, Japan.
⁷ Department of Chemistry and Life Science, Yokohama National University, Kanagawa 240-8501, Japan; yabuuchi-naoaki-pw@ynu.ac.jp.
⁸ Advanced Chemical Energy Research Center, Yokohama National University, Kanagawa 240-8501, Japan.
⁹ Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Kyoto 615-8245, Japan.

Abstract

The development of inherently safe energy devices is a key challenge, and aqueous Li-ion batteries draw large attention for this purpose. Due to the narrow electrochemical stable potential window of aqueous electrolytes, the energy density and the selection of negative electrode materials are significantly limited. For achieving durable and high-energy aqueous Li-ion batteries, the development of negative electrode materials exhibiting a large capacity and low potential without triggering decomposition of water is crucial. Herein, a type of a negative electrode material (i.e., Li _x Nb_2/7Mo_3/7O₂) is proposed for high-energy aqueous Li-ion batteries. Li _x Nb_2/7Mo_3/7O₂ delivers a large capacity of ∼170 mA ⋅ h ⋅ g^-1 with a low operating potential range of 1.9 to 2.8 versus Li/Li⁺ in 21 m lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) aqueous electrolyte. A full cell consisting of Li_1.05Mn_1.95O₄/Li_9/7Nb_2/7Mo_3/7O₂ presents high energy density of 107 W ⋅ h ⋅ kg^-1 as the maximum value in 21 m LiTFSA aqueous electrolyte, and 73% in capacity retention is achieved after 2,000 cycles. Furthermore, hard X-ray photoelectron spectroscopy study reveals that a protective surface layer is formed at the surface of the negative electrode, by which the high-energy and durable aqueous batteries are realized with Li _x Nb_2/7Mo_3/7O₂ This work combines a high capacity with a safe negative electrode material through delivering the Mo-based oxide with unique nanosized and metastable characters.

Keywords: aqueous battery; metastable; rock-salt oxide.