因具有大量的晶界和离子扩散通道,低结晶度的电极活性材料有望在储能领域中实现更好的性能.然而在大多数应用中通常是结晶良好的样品具有更好的稳定性,稳定性较差限制了低结晶样品在相关研究领域的应用.本文利用一种溶剂热法调控N-甲基...因具有大量的晶界和离子扩散通道,低结晶度的电极活性材料有望在储能领域中实现更好的性能.然而在大多数应用中通常是结晶良好的样品具有更好的稳定性,稳定性较差限制了低结晶样品在相关研究领域的应用.本文利用一种溶剂热法调控N-甲基吡咯烷酮和水混合溶剂的体积比以合成低结晶度的镍钴氢氧化物(NiCo-OH-L).研究发现,将合成的镍钴氢氧化物用作镍-锌电池正极时,NiCo-OH-L不仅表现出与高结晶度的同类样品相当的循环稳定性能,而且在1-50 A g^(-1)的电流范围内显示出更高的容量以及容量保持率.其优异的电化学性能可归因于低结晶的结构,显著提高的比表面积和降低的电荷转移电阻.此外,NiCo-OH-L的钴组分进一步提高了倍率和循环稳定性能.NiCo-OH-L在1 A g^(-1)时的比容量达到238.9 mA h g^(-1),当电流密度升至50 A g^(-1)时的容量仍有116.4 mA h g^(-1),显示出高容量和高倍率性能.不仅如此,由NiCo-OH-L组装成的镍-锌电池在不同的电流和循环周期下也表现出较高的性能.展开更多
Conversion-type anode materials hold great potential for Li+storage applications owing to their high specific capacity,while large volume expansion and poor electrical conductivity limit their rate and cycling perform...Conversion-type anode materials hold great potential for Li+storage applications owing to their high specific capacity,while large volume expansion and poor electrical conductivity limit their rate and cycling performances.Herein,a bimetal ZnMn-based metal-organic framework(ZnMn-MOF)is engineered for in situ conversion of MnO-encapsulated porous carbon(MnO/PC)composite.The templating and activation effects of coordinated Zn endow the converted PC matrix with a highly porous structure.This enhances the compatibility of PC matrix with MnO particles,resulting in the full encapsulation of MnO particles in the PC matrix.More significantly,the PC matrix provides enough void space to buffer the volume change,which fully wraps the MnO without crack or fracture during repeated cycling.As a result,MnO/PC shows high charge storage capability,extraordinary rate performance,and long-term cycling stability at the same time.Thus MnO/PC exhibits high delithiation capacities of 768mA h g^(-1)at 0.1Ag^(-1)and 487mA h g^(-1)at a high rate of 0.7Ag^(-1),combined with an unattenuated cycling performance after 500 cycles at 0.3Ag^(-1).More significantly,MnO/PC demonstrates a well-matched performance with the capacitive activated carbon electrode in a Li-ion capacitor(LIC)full cell.LIC demonstrates a high specific energy of 153.6W h kg^(-1)at 210W kg^(-1),combined with a specific energy of 71.8W h kg^(-1)at a high specific power of 63.0kW kg^(-1).展开更多
基金financially supported by the National Natural Science Foundation of China(21905148)。
文摘因具有大量的晶界和离子扩散通道,低结晶度的电极活性材料有望在储能领域中实现更好的性能.然而在大多数应用中通常是结晶良好的样品具有更好的稳定性,稳定性较差限制了低结晶样品在相关研究领域的应用.本文利用一种溶剂热法调控N-甲基吡咯烷酮和水混合溶剂的体积比以合成低结晶度的镍钴氢氧化物(NiCo-OH-L).研究发现,将合成的镍钴氢氧化物用作镍-锌电池正极时,NiCo-OH-L不仅表现出与高结晶度的同类样品相当的循环稳定性能,而且在1-50 A g^(-1)的电流范围内显示出更高的容量以及容量保持率.其优异的电化学性能可归因于低结晶的结构,显著提高的比表面积和降低的电荷转移电阻.此外,NiCo-OH-L的钴组分进一步提高了倍率和循环稳定性能.NiCo-OH-L在1 A g^(-1)时的比容量达到238.9 mA h g^(-1),当电流密度升至50 A g^(-1)时的容量仍有116.4 mA h g^(-1),显示出高容量和高倍率性能.不仅如此,由NiCo-OH-L组装成的镍-锌电池在不同的电流和循环周期下也表现出较高的性能.
基金supported by the National Natural Science Foundation of China(21905148)China Postdoctoral Science Foundation(2019T120567 and 2017M612184)+2 种基金the 1000-Talents Planthe World-Class Discipline Programthe Taishan Scholars Advantageous and Distinctive Discipline Program of Shandong province for supporting the research team of energy storage materials.
文摘Conversion-type anode materials hold great potential for Li+storage applications owing to their high specific capacity,while large volume expansion and poor electrical conductivity limit their rate and cycling performances.Herein,a bimetal ZnMn-based metal-organic framework(ZnMn-MOF)is engineered for in situ conversion of MnO-encapsulated porous carbon(MnO/PC)composite.The templating and activation effects of coordinated Zn endow the converted PC matrix with a highly porous structure.This enhances the compatibility of PC matrix with MnO particles,resulting in the full encapsulation of MnO particles in the PC matrix.More significantly,the PC matrix provides enough void space to buffer the volume change,which fully wraps the MnO without crack or fracture during repeated cycling.As a result,MnO/PC shows high charge storage capability,extraordinary rate performance,and long-term cycling stability at the same time.Thus MnO/PC exhibits high delithiation capacities of 768mA h g^(-1)at 0.1Ag^(-1)and 487mA h g^(-1)at a high rate of 0.7Ag^(-1),combined with an unattenuated cycling performance after 500 cycles at 0.3Ag^(-1).More significantly,MnO/PC demonstrates a well-matched performance with the capacitive activated carbon electrode in a Li-ion capacitor(LIC)full cell.LIC demonstrates a high specific energy of 153.6W h kg^(-1)at 210W kg^(-1),combined with a specific energy of 71.8W h kg^(-1)at a high specific power of 63.0kW kg^(-1).
