高安全、長寿命、高エネルギー密度の水系リチウムイオン電池の開発に成功
藪内 直明 教授（横国大：計画A04）増田 卓也GL（NIMS：公募A02）
【概要】
横浜国立大学の藪内教授らの研究グループは、不燃性で安全な水系電解液を用い、さらに、独自に開発した岩塩型モリブデン系酸化物負極材料を利用することで、従来の可燃性の有機溶媒を用いるリチウムイオン電池と同等の長寿命を実現する安全・安心なリチウムイオン電池の開発に成功しました。 自然エネルギーの活用には大規模蓄電池システムが必要とされていますが、燃えない安全なリチウムイオン電池はこれらの用途へ応用が期待できる新しい技術です。
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., LixNb2/7Mo3/7O2) is proposed for high-energy aqueous Li-ion batteries. LixNb2/7Mo3/7O2 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 Li1.05Mn1.95O4/Li9/7Nb2/7Mo3/7O2 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 LixNb2/7Mo3/7O2. This work combines a high capacity with a safe negative electrode material through delivering the Mo-based oxide with unique nanosized and metastable characters.
Jeongsik Yun, Ryota Sagehashi, Yoshihiko Sato, Takuya Masuda, Satoshi Hoshino, Hongahally Basappa Rajendra, Kazuki Okuno, Akihisa Hosoe, Aliaksandr S. Bandarenka, Naoaki Yabuuchi, PNAS 118, e2024969118, (2021). "Nanosized and metastable molybdenum oxides as negative electrode materials for durable high-energy aqueous Li-ion batteries"
Published on November 30, 2021
