Ding Xiaobo, Lin Jianhao, Huang Huiying, Zhao Bote, Xiong Xunhui
School of Environment and Energy, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510640, People's Republic of China.
Nanomicro Lett. 2023 Aug 10;15(1):195. doi: 10.1007/s40820-023-01172-9.
Niobium pentoxide (NbO) anodes have gained increasing attentions for high-power lithium-ion batteries owing to the outstanding rate capability and high safety. However, NbO anode suffers poor cycle stability even after modified and the unrevealed mechanisms have restricted the practical applications. Herein, the over-reduction of Nb has been demonstrated to be the critical reason for the capacity loss for the first time. Besides, an effective competitive redox strategy has been developed to solve the rapid capacity decay of NbO, which can be achieved by the incorporation of vanadium to form a new rutile VNbO anode. The highly reversible V/V redox couple in VNbO can effectively inhibit the over-reduction of Nb. Besides, the electron migration from V to Nb can greatly increase the intrinsic electronic conductivity for VNbO. As a result, VNbO anode delivers a high capacity of 206.1 mAh g at 0.1 A g, as well as remarkable cycle performance with a retention of 93.4% after 2000 cycles at 1.0 A g. In addition, the assembled lithium-ion capacitor demonstrates a high energy density of 44 Wh kg at 5.8 kW kg. In summary, our work provides a new insight into the design of ultra-fast and durable anodes.
五氧化二铌（NbO）阳极由于其出色的倍率性能和高安全性，在高功率锂离子电池领域受到了越来越多的关注。然而，即使经过改性，NbO阳极的循环稳定性仍然较差，其尚未揭示的机制限制了其实际应用。在此，首次证明Nb的过度还原是容量损失的关键原因。此外，还开发了一种有效的竞争性氧化还原策略来解决NbO的快速容量衰减问题，这可以通过引入钒形成新的金红石型VNbO阳极来实现。VNbO中高度可逆的V/V氧化还原对可以有效抑制Nb的过度还原。此外，从V到Nb的电子迁移可以大大提高VNbO的本征电子电导率。结果，VNbO阳极在0.1 A g下具有206.1 mAh g的高容量，以及在1.0 A g下2000次循环后93.4%的保留率的出色循环性能。此外，组装的锂离子电容器在5.8 kW kg下表现出44 Wh kg的高能量密度。总之，我们的工作为超快耐用阳极的设计提供了新的见解。
