Scalable self-growth of Ni@NiO core-shell electrode with ultrahigh capacitance and super-long cyclic stability for supercapacitors
Scalable self-growth of Ni@NiO core-shell electrode with ultrahigh capacitance and super-long cyclic stability for supercapacitors
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DOI：
10.1038/am.2014.78
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发表时间：
2014-09
影响因子：
9.7
通讯作者：
Minghao Yu;Wang Wang-Wang;Cheng Li;Teng Zhai;Xihong Lu;Y. Tong
中科院分区：
文献类型：
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作者：
Minghao Yu;Wang Wang-Wang;Cheng Li;Teng Zhai;Xihong Lu;Y. Tong
三维（3D）电极由于其独特的结构和优异的电化学性能已被证明是高性能超级电容器的有希望的候选者。然而，当前3D电极的制造工艺是不可扩展的。本文中，已经开发了一种新颖且具有成本效益的活化方法，以宏观地制备具有增强的电化学性能的3D多孔Ni@NiO核壳电极。通过在3 M HCl溶液中活化的商业Ni泡沫（NF）获得的多孔Ni@NiO核壳电极在8 mA cm-2的高电流密度下产生2.0F cm-2的电容面积，其显著高于大多数报道的3D NF基电极的电容面积。此外，活化的NF（ANF）电极具有超长的循环稳定性。由于循环过程中增加的可及表面积和电化学活性NiO的连续形成，ANF电极的面积电容没有表现出任何衰减，而是在100 mV s-1下100 000次循环后从0.47 F cm-2增加到1.27 F cm-2。这是通过3D NF基电极实现的最佳循环稳定性。此外，还制备了基于所制备的ANF阴极和还原的氧化石墨烯（RGO）阳极的高性能不对称超级电容器（ASC）装置。ANF//RGO-ASC设备能够提供1.06 mWh cm−3的最大能量密度和0.42 W cm−3的最大功率密度。来自中国的研究人员发现了一种使用泡沫镍大规模生产超级电容器的成本效益高的方法。这种三维多孔金属由于其轻质、耐腐蚀的结构而成为高容量储能的理想电极。然而，为了实现超级电容，研究人员必须将活性物质（如石墨烯）深入镍孔中。来自中山大学的Xihong Lu和他的同事通过将商业级泡沫镍浸入热盐酸中几分钟解决了这个问题。一步反应使原先光滑的泡沫镍表面产生凹坑，并产生一层薄薄的氧化镍外壳，包围着镍的内核。电化学实验表明，有利的核-壳结构与从酸蚀刻获得的更易接近的表面积相结合，产生了能量密集的超级电容器电极，其有效地进行超过100，000次充电-再充电循环。提出了一种新的、低成本的活化工艺，在HCl水溶液中通过活化泡沫镍（ANF）宏观制备三维多孔Ni@NiO核壳电极。ANF电极在8 mA cm−2的高电流密度下产生了2.0 F cm−2的显著面积电容，并且在100 000次循环后表现出良好的长期循环稳定性而没有任何电容衰减。
Three-dimensional (3D) electrodes have been demonstrated to be promising candidates for high-performance supercapacitors because of their unique architectures and outstanding electrochemical properties. However, the fabrication process for current 3D electrodes is not scalable. Herein, a novel and cost-effective activation process has been developed to macroscopically produce 3D porous Ni@NiO core-shell electrodes with enhanced electrochemical properties. The porous Ni@NiO core-shell electrode obtained by activated commercial Ni foam (NF) in a 3 M HCl solution yields an ultrahigh areal capacitance of 2.0 F cm−2 at a high current density of 8 mA cm−2, which is substantially higher than that of most reported 3D NF-based electrodes. Moreover, the activated NF (ANF) electrode exhibited super-long cycling stability. Owing to the increased accessible surface area and continual formation of electrochemically active NiO during cycling, the areal capacitance of the ANF electrode did not exhibit any decay and instead increased from 0.47 to 1.27 F cm−2 after 100 000 cycles at 100 mV s−1. This is the best cycling stability achieved by a 3D NF-based electrode. Additionally, a high-performance asymmetrical supercapacitor (ASC) device based on the as-prepared ANF cathode and a reduced graphene oxide (RGO) anode was also prepared. The ANF//RGO-ASC device was able to deliver a maximum energy density of 1.06 mWh cm−3 and a maximum power density of 0.42 W cm−3. Researchers from China have discovered a cost-effective way to produce supercapacitors on large scales using nickel foam. This three-dimensional porous metal is an ideal electrode for high-capacity energy storage because of its lightweight, corrosion-resistant structure. To achieve supercapacitance, however, researchers must insert active substances, such as graphene, deep into the nickel pores. Xihong Lu and colleagues from Sun Yat-Sen University solved this problem by immersing commercial-grade nickel foam into hot hydrochloric acid for several minutes. The one-step reaction pitted the formerly smooth nickel foam surface and created a thin outer ‘shell’ of nickel oxide that surrounded an inner nickel ‘core’. Electrochemical experiments revealed that the favorable core–shell structure, combined with a more accessible surface area achieved from the acid etching, yielded an energy-dense supercapacitor electrode that was effective for more than 100,000 charge–recharge cycles. A novel and cost-effective activation process has been developed to macroscopically produce three-dimensional (3D) porous Ni@NiO core-shell electrode by activated Ni foam (ANF) in HCl aqueous solution. The ANF electrode yielded a remarkable areal capacitance of 2.0 F cm−2 at a high current density of 8 mA cm−2 and exhibited ultrahigh long-term cycling stability without any decay of capacitance after 100 000 cycles.