Yadav Priya, Putro Dimas, Kumari Nisha, Kim Jaekook, Rai Alok Kumar
Department of Chemistry, University of Delhi, Delhi, 110007, India.
Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-dong, Bukgu, Gwangju, 500-757, Republic of Korea.
Phys Chem Chem Phys. 2023 Aug 9;25(31):21082-21088. doi: 10.1039/d3cp02179c.
Recently, aqueous zinc ion batteries (AZIBs) have attracted significant attention owing to their high safety, low cost, and abundant raw materials. However, finding an affordable and stable cathode, which can reversibly store a substantial amount of Zn ions without damaging the original crystal structure, is still a major challenge for the practical application of ZIBs. It has already been demonstrated that δ-MnO is a promising cathode for AZIBs owing to its layered structure and superior electrochemical performance; however, the reported results are still unsatisfactory (especially cyclability). Thus, using an oil bath method, we have fabricated a δ-MnO cathode that exhibits a unique mixed phase morphology of mostly spherical nanoparticles and a few nanorods. It is believed that some of the nanoparticles are agglomerated to form nanorods, which may eventually help to offer numerous active sites for Zn diffusion, enhancing the electrolyte osmosis and the contact area between the electrode and electrolyte. The obtained cathode delivers a high reversible capacity of ∼204 mA h g for the 100th cycle and ∼75 mA h g over 1000 cycles at a high current density of 3000 mA g with stable long-range cycling. results indicate the mechanism of formation of ZnMnO during discharge, followed by the evolution of the layered δ-MnO during charge.
最近，水系锌离子电池（AZIBs）因其高安全性、低成本和丰富的原材料而备受关注。然而，找到一种价格合理且稳定的正极，能够在不破坏原始晶体结构的情况下可逆地存储大量锌离子，仍然是水系锌离子电池实际应用中的一个重大挑战。已经证明，δ-MnO由于其层状结构和优异的电化学性能，是一种有前途的水系锌离子电池正极；然而，报道的结果仍然不尽人意（尤其是循环稳定性）。因此，我们采用油浴法制备了一种δ-MnO正极，它呈现出一种独特的混合相形态，主要是球形纳米颗粒和少量纳米棒。据信，一些纳米颗粒团聚形成纳米棒，这最终可能有助于为锌离子扩散提供大量活性位点，增强电解质渗透以及电极与电解质之间的接触面积。所制备的正极在3000 mA g的高电流密度下，第100次循环时具有约204 mA h g的高可逆容量，在1000次循环中约为~75 mA h g，且具有稳定的长循环性能。结果表明了放电过程中ZnMnO的形成机制，随后是充电过程中层状δ-MnO的演变。
