在 MnO2 中选择性和赝电容性 Zn 离子插入的高能稳定低温 Zn-MnO2 水系电池,Advanced Materials

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在 MnO2 中选择性和赝电容性 Zn 离子插入的高能稳定低温 Zn-MnO2 水系电池
Advanced Materials ( IF 27.4 ) Pub Date : 2022-03-25 , DOI: 10.1002/adma.202201510
Siyuan Gao _{1,

2} , Bomin Li _{1,

2} , Haiyan Tan ₃ , Fan Xia ₁ , Olusola Dahunsi ₁ , Wenqian Xu ₄ , Yuzi Liu ₅ , Rongyue Wang ₂ , Yingwen Cheng ₁

Affiliation

实际应用中水系 Zn-MnO ₂电池面临的一个主要挑战是其在冰点以下的性能无法接受。这里描述了使用简单的 Zn(ClO ₄ ) ₂水性电解质用于全天候 Zn-MnO ₂电池，甚至低至 -60 °C。对称的、庞大的 ClO ₄^-阴离子有效地破坏了水分子之间的氢键，即使在冷冻时也能提供固有的离子扩散，并在 -30 °C 下在 MnO _{2阴极上实现 ≈260 mAh g}^{-1 。}已确定低于冰点的循环将 MnO ₂正极上的反应机制从不稳定的 H ⁺插入主要是赝电容性Zn ²⁺插入，这将MnO ₂纳米纤维转化为复杂的锌化MnO _x，这些MnO x 在很大程度上是无序的并且看起来像皱巴巴的纸片。-30 °C 下的 Zn ²⁺插入比 20 °C 下更快且更稳定，并且在没有 Mn ²⁺添加剂的情况下在 1000 次循环中提供约 80% 的容量保持率。此外，简单的 Zn(ClO ₄ ) ₂电解质还可以在 -30 °C 下实现几乎完全可逆且无枝晶的 Zn 负极，库仑效率约为 98%。经实验验证的单位能量密度为 148 Wh kg ^-1的Zn-MnO _2原型进一步证明了负正比为 1.5 和电解质与容量比为 2.0。

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High-Energy and Stable Subfreezing Aqueous Zn–MnO2 Batteries with Selective and Pseudocapacitive Zn-Ion Insertion in MnO2

One major challenge of aqueous Zn–MnO₂ batteries for practical applications is their unacceptable performance below freezing temperatures. Here the use of simple Zn(ClO₄)₂ aqueous electrolytes is described for all-weather Zn–MnO₂ batteries even down to −60 °C. The symmetric, bulky ClO₄⁻ anion effectively disrupts hydrogen bonds between water molecules and provides intrinsic ion diffusion even while frozen, and enables ≈260 mAh g⁻¹ on MnO₂ cathodes at −30 °C . It is identified that subfreezing cycling shifts the reaction mechanism on the MnO₂ cathode from unstable H⁺ insertion to predominantly pseudocapacitive Zn²⁺ insertion, which converts MnO₂ nanofibers into complicated zincated MnO_x that are largely disordered and appeared as crumpled paper sheets. The Zn²⁺ insertion at −30 °C is faster and much more stable than at 20 °C, and delivers ≈80% capacity retention for 1000 cycles without Mn²⁺ additives. In addition, simple Zn(ClO₄)₂ electrolyte also enables a nearly fully reversible and dendrite-free Zn anode at −30 °C with ≈98% Coulombic efficiency. Zn–MnO₂ prototypes with an experimentally verified unit energy density of 148 Wh kg⁻¹ at a negative-to-positive ratio of 1.5 and an electrolyte-to-capacity ratio of 2.0 are further demonstrated.

更新日期：2022-03-25

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