Li Zhaoqian, Ren Yingke, Mo Lie, Liu Chaofeng, Hsu Kevin, Ding Youcai, Zhang Xianxi, Li Xiuling, Hu Linhua, Ji Denghui, Cao Guozhong
Key Laboratory of Photovoltaic and Energy Conservation Materials, CAS, Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China.
Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States.
ACS Nano. 2020 May 26;14(5):5581-5589. doi: 10.1021/acsnano.9b09963. Epub 2020 May 13.
The aqueous zinc ion battery has emerged as a promising alternative technology for large-scale energy storage due to its low cost, natural abundance, and high safety features. However, the sluggish kinetics stemming from the strong electrostatic interaction of divalent zinc ions in the host crystal structure is one of challenges for highly efficient energy storage. Oxygen vacancies (V), in the present work, lead to a larger tunnel structure along the axis, which improves the reactive kinetics and enhances Zn-ion storage capability in VO (B) cathode. DFT calculations further support that V in VO (B) result in a narrower bandgap and lower Zn ion diffusion energy barrier compared to those of pristine VO (B). V-rich VO (B) achieves a specific capacity of 375 mAh g at a current density of 100 mA g and long-term cyclic stability with retained specific capacity of 175 mAh g at 5 A g over 2000 cycles (85% capacity retention), higher than that of VO (B) nanobelts (280 mAh g at 100 mA g and 120 mAh g at 5 A g, 65% capacity retention).
水系锌离子电池因其低成本、天然丰度高和高安全特性，已成为一种很有前景的大规模储能替代技术。然而，主体晶体结构中二价锌离子的强静电相互作用导致的缓慢动力学是高效储能面临的挑战之一。在本工作中，氧空位（V）沿 轴导致更大的隧道结构，这改善了反应动力学并增强了VO（B）阴极中的锌离子存储能力。密度泛函理论计算进一步支持，与原始VO（B）相比，VO（B）中的V导致更窄的带隙和更低的锌离子扩散能垒。富V的VO（B）在100 mA g的电流密度下实现了375 mAh g的比容量，并具有长期循环稳定性，在5 A g下经过2000次循环（容量保持率85%）后比容量保持在175 mAh g，高于VO（B）纳米带（在100 mA g下为280 mAh g，在5 A g下为120 mAh g，容量保持率65%）。
