Fukuma Ryutaro, Harada Maho, Zhao Wenwen, Sawamura Miho, Noda Yusuke, Nakayama Masanobu, Goto Masato, Kan Daisuke, Shimakawa Yuichi, Yonemura Masao, Ikeda Naohiro, Watanuki Ryuta, Andersen Henrik L, D'Angelo Anita M, Sharma Neeraj, Park Jiwon, Byon Hye Ryung, Fukuyama Sayuri, Han Zhenji, Fukumitsu Hitoshi, Schulz-Dobrick Martin, Yamanaka Keisuke, Yamagishi Hirona, Ohta Toshiaki, Yabuuchi Naoaki
Department of Applied Chemistry, Tokyo Denki University, 5 Senju Asahi-cho, Adachi-ku, Tokyo, Tokyo 120-8551, Japan.
Frontier Research Institute for Materials Science (FRIMS), Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.
ACS Cent Sci. 2022 Jun 22;8(6):775-794. doi: 10.1021/acscentsci.2c00238. Epub 2022 May 23.
Dependence on lithium-ion batteries for automobile applications is rapidly increasing. The emerging use of anionic redox can boost the energy density of batteries, but the fundamental origin of anionic redox is still under debate. Moreover, to realize anionic redox, many reported electrode materials rely on manganese ions through π-type interactions with oxygen. Here, through a systematic experimental and theoretical study on a binary system of LiNbO-NiO, we demonstrate for the first time the unexpectedly large contribution of oxygen to charge compensation for electrochemical oxidation in Ni-based materials. In general, for Ni-based materials, ., LiNiO, charge compensation is achieved mainly by Ni oxidation, with a lower contribution from oxygen. In contrast, for LiNbO-NiO, oxygen-based charge compensation is triggered by structural disordering and σ-type interactions with nickel ions, which are associated with a unique environment for oxygen, ., a linear Ni-O-Ni configuration in the disordered system. Reversible anionic redox with a small hysteretic behavior was achieved for LiNiNbO with a cation-disordered Li/Ni arrangement. Further Li enrichment in the structure destabilizes anionic redox and leads to irreversible oxygen loss due to the disappearance of the linear Ni-O-Ni configuration and the formation of unstable Ni ions with high oxidation states. On the basis of these results, we discuss the possibility of using σ-type interactions for anionic redox to design advanced electrode materials for high-energy lithium-ion batteries.
汽车应用对锂离子电池的依赖正在迅速增加。阴离子氧化还原的新兴应用可以提高电池的能量密度，但阴离子氧化还原的基本起源仍在争论之中。此外，为了实现阴离子氧化还原，许多报道的电极材料通过与氧的π型相互作用依赖锰离子。在这里，通过对LiNbO-NiO二元体系的系统实验和理论研究，我们首次证明了在镍基材料中氧对电化学氧化电荷补偿的意外巨大贡献。一般来说，对于镍基材料，如LiNiO，电荷补偿主要通过镍的氧化来实现，氧的贡献较低。相比之下，对于LiNbO-NiO，基于氧的电荷补偿是由结构无序和与镍离子的σ型相互作用引发的，这与氧的独特环境有关，即在无序体系中的线性Ni-O-Ni构型。对于具有阳离子无序Li/Ni排列的LiNiNbO，实现了具有小滞后行为的可逆阴离子氧化还原。结构中进一步的锂富集使阴离子氧化还原不稳定，并由于线性Ni-O-Ni构型的消失和高氧化态不稳定镍离子的形成而导致不可逆的氧损失。基于这些结果，我们讨论了利用σ型相互作用进行阴离子氧化还原以设计用于高能锂离子电池的先进电极材料的可能性。
