一种高度稳定的 δ-MnO2 正极，具有优异的电化学性能，适用于可充电水性锌离子电池,Physical Chemistry Chemical Physics

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一种高度稳定的 δ-MnO2 正极，具有优异的电化学性能，适用于可充电水性锌离子电池
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2023-07-19 , DOI: 10.1039/d3cp02179c
Priya Yadav ₁ , Dimas Putro ₂ , Nisha Kumari ₁ , Jaekook Kim ₂ , Alok Kumar Rai ₁

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近年来，水性锌离子电池（AZIB）因其安全性高、成本低、原材料丰富而受到广泛关注。然而，寻找一种经济实惠且稳定的阴极，能够可逆地储存大量Zn ²⁺离子而不破坏原始晶体结构，仍然是ZIBs实际应用的一个重大挑战。已经证明δ-MnO ₂由于其层状结构和优异的电化学性能而成为AZIBs的有前途的正极。然而，报告的结果仍然不令人满意（特别是循环性）。因此，使用油浴法，我们制备了δ-MnO ₂阴极，其表现出独特的混合相形态，主要为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Zn ²⁺扩散提供大量活性位点，增强电解质渗透以及电极和电解质之间的接触面积。^{所获得的正极在3000 mA g -1的}高电流密度下，在第100次循环中提供～204 mA hg ^-1的高可逆容量，在1000次循环中提供～75 mA hg ^-1的高可逆容量，并具有稳定的长程循环。非原位结果表明了放电过程中形成 ZnMn ₂ O ₄的机制，随后在充电过程中演化出层状 δ-MnO _{2 。}

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A highly stable δ-MnO2 cathode with superior electrochemical performance for rechargeable aqueous zinc ion batteries

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 Zn²⁺ 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-MnO₂ 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-MnO₂ 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 Zn²⁺ 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⁻¹ for the 100th cycle and ∼75 mA h g⁻¹ over 1000 cycles at a high current density of 3000 mA g⁻¹ with stable long-range cycling. Ex situ results indicate the mechanism of formation of ZnMn₂O₄ during discharge, followed by the evolution of the layered δ-MnO₂ during charge.

更新日期：2023-07-19

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