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Principles of interlayer-spacing regulation of layered vanadium phosphates for superior zinc-ion batteries
Energy & Environmental Science ( IF 32.5 ) Pub Date : 2021-5-26 , DOI: 10.1039/d1ee01158h
Linfeng Hu 1, 2, 3, 4, 5 , Zeyi Wu 4, 5, 6, 7 , Chengjie Lu 1, 2, 3, 4 , Fei Ye 1, 2, 3, 4 , Qiang Liu 1, 2, 3, 4 , Zhengming Sun 1, 2, 3, 4
Affiliation  

Layered vanadium phosphate (VOPO4·2H2O) is reported as a promising cathode material for rechargeable aqueous Zn2+ batteries (ZIBs) owing to its unique layered framework and high discharge plateau. However, its sluggish Zn2+ diffusion kinetics, low specific capacity and poor electrochemical stability remain major issues in battery application. In this work, a group of phenylamine (PA)–intercalated VOPO4·2H2O materials with varied interlayer spacing (14.8, 15.6 and 16.5 Å) is synthesized respectively via a solvothermal method for the cathode of aqueous ZIBs. The specific capacity is quite dependent on the d-spacing in the PA–VOPO4·2H2O system following an approximate linear tendency, and the maximum interlayer spacing (16.5 Å phase) results in a discharge capacity of 268.2 mA h g−1 at 0.1 A g−1 with a high discharge plateau of ∼1.3 V and an energy density of 328.5 W h kg−1. Both of the experimental data and DFT calculation identify that the optimal 16.5 Å spacing can boost fast zinc-ion diffusion with an ultrahigh diffusion coefficient of ∼5.7 × 10−8 cm−2 s−1. The intercalation of PA molecules also significantly increases the hydrophobility in the aqueous electrolyte, resulting in the inhibition of the decomposition/dissolution of VOPO4·2H2O and remarkably improved cycling stability over 2000 cycles at 5.0 A g−1 with a capacity retention of ∼200 mA h g−1. Our study provides a feasible solution for the sluggish Zn2+ diffusion kinetics and poor cyclic stability, and also shows a clear understanding of the interlayer chemistry principle of layered phosphates toward high-performance zinc-ion batteries.

中文翻译:

优质锌离子电池层状磷酸钒层间距调节原理

据报道,层状磷酸钒 (VOPO 4 ·2H 2 O)因其独特的层状框架和高放电平台而被认为是可充电水相 Zn 2+电池 (ZIBs) 的一种有前途的正极材料。然而,其缓慢的Zn 2+扩散动力学、低比容量和差的电化学稳定性仍然是电池应用中的主要问题。在这项工作中,通过溶剂热法分别合成了一组具有不同层间距(14.8、15.6和 16.5 Å)的苯胺 (PA) 插层 VOPO 4 ·2H 2 O 材料,用于水性 ZIBs 的阴极。比容量非常依赖于PA-VOPO 中的d间距4 ·2H 2 O 系统遵循近似线性趋势,最大层间距(16.5 Å 相)导致在0.1 A g -1 下放电容量为 268.2 mA hg -1,放电平台高约 1.3 V 和328.5 W h kg -1 的能量密度。实验数据和 DFT 计算都表明,最佳的 16.5 Å 间距可以促进快速的锌离子扩散,其超高扩散系数为 ~5.7 × 10 -8 cm -2 s -1。PA分子的嵌入也显着增加了水性电解质中的疏水性,从而抑制了VOPO 4 ·2H的分解/溶解2 O,并且在 5.0 A g -1 的2000 次循环中显着提高了循环稳定性,容量保持率约为 200 mA hg -1。我们的研究为缓慢的Zn 2+扩散动力学和较差的循环稳定性提供了可行的解决方案,也表明对层状磷酸盐对高性能锌离子电池的层间化学原理的清晰理解。
更新日期:2021-06-18
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