马俊红
Well-dispersed Ni3Fe nanoparticles with a N-doped porous carbon shell for highly efficient rechargeable Zn-air batteries
NiFe-based nanoparticles attached to heteroatom-doped carbon are found to act as tremendously efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts. Nevertheless, it is extremely challenging to control the particle size and avoid aggregation. Herein, nitrogen-doped carbon encapsulated Ni3Fe nanoparticles (Ni3Fe@NC) are prepared by two-stage pyrolysis with a low rate based on the in situ structural evolution of FeNi-PBAs. The strategy results in uniform Ni3Fe nanoparticles anchoring within the carbon shell and thus facilitating interfacial interaction. Benefiting from the enhanced synergism between Ni3Fe particles and NC layers, Ni3Fe@NC-600 demonstrates the best catalytic activity and durability, not only with almost the same onset potential (1.01 V) as commercial Pt/C for the ORR but also satisfactory OER performance with a low overpotential of 0.29 V at 10 mA cm-2 in 0.1 M KOH. Moreover, the Zn-air battery assembled using the Ni3Fe@NC-600 cathode exhibits superior performance to commercial Pt/C + RuO2. The simple and scalable method of this work provides insight into the fabrication of high-performance and cost-effective bifunctional oxygen electrocatalysts.
分散良好的具有氮掺杂多孔碳壳的Ni3Fe纳米颗粒用于高效可充电锌空气电池
研究发现，附着在杂原子掺杂碳上的NiFe基纳米颗粒可作为非常有效的氧还原反应(ORR)和氧析出反应(OER)电催化剂。然而，控制颗粒尺寸和避免聚集是极具挑战性的。本文基于FeNi-PBAs的原位结构演化，通过两阶段慢速升温热解制备了氮掺杂碳包封的Ni3Fe纳米颗粒(Ni3Fe@NC)。该策略导致Ni3Fe纳米颗粒均匀地锚定在碳壳内，从而促进界面相互作用。受益于Ni3Fe颗粒和NC层之间增强的协同作用，Ni3Fe@NC-600表现出最佳的催化活性和耐久性，不仅具有几乎与商业Pt/C相同的ORR起始电位(1.01 V)，而且在0.1 M KOH溶液中OER在10 mA cm-2电流密度下也表现出令人满意的低过电位(0.29 V)。此外，使用Ni3Fe@NC-600作为阴极组装的锌-空电池表现出优于商业Pt/C + RuO2的性能。本研究简单和可扩展的方法为高性能和高性价比的双功能氧电催化剂的制备提供了见解。
https://doi.org/10.1039/D2NR05827H
Al doped manganous oxide for high-performance aqueous Zn-ion batteries
MnO has been proved to be a feasible cathode material for aqueous zinc ion batteries, but the absence of tunnel structure in MnO and strong electrostatic interaction between MnO and guest ions make Zn/MnO batteries exhibit poor performance. To remedy this intrinsic defect, we propose a strategy of Al doping to modify MnO, which not only introduces abundant Mn vacancies to improve Zn2+ diffusion, but also increases the specific surface area and pore size of MnO to enhance the wettability of cathode towards electrolyte. We also found that Al-MnO converted into ramsdellite-MnO2 (R-MnO2) during charge/discharge, which further suppresses Mn2+ dissolution. Employing such Al-MnO as cathode material, the assembled aqueous zinc ion batteries (ZIBs) shows high specific capacity (345 mAh g-1 at 0.1 A g-1) and possesses a long-term capacity retention of about 89% over 500 cycles at 1.0 A g-1. This work offers novel insights into the cathode design for low cost and high safety aqueous ZIBs with excellent electrochemical performance.
铝掺杂氧化锰用于高性能水系锌离子电池
MnO已被证明可作为水系锌离子电池的正极材料，但由于MnO缺乏隧道结构且与客体离子之间存在强烈的静电相互作用，导致Zn/MnO电池性能较差。为了克服这一固有缺陷，我们提出了一种Al掺杂修饰MnO的策略。该策略不仅引入了丰富的Mn空位以改善Zn2+扩散，还增加了MnO的比表面积和孔径，增强了电解液对正极的润湿性。此外，在充放电过程中，Al-MnO进一步转化为R-MnO2，并抑制了Mn2+溶解。采用这种Al-MnO作为正极材料，组装的水系锌离子电池(ZIBs)展现出较高的比容量(0.1 A g-1时为345 mAh g-1)，在1.0 A g-1下循环500次后容量保持率约为89%。这项工作为设计低成本、高安全性且具有优异电化学性能的水系ZIBs正极材料提供了新思路。
https://doi.org/10.1016/j.jpowsour.2022.232353
