制备了一种空心碳球负载二硫化硒(SeS_2@HCS)复合材料作为锂离子电池正极材料。通过扫描电子显微镜(SEM),X射线衍射(XRD)以及氮气吸脱附测试(BET)等对产物形貌、组成和结构进行了表征。实验结果显示,采用模板法结合化学聚合法可以合成...制备了一种空心碳球负载二硫化硒(SeS_2@HCS)复合材料作为锂离子电池正极材料。通过扫描电子显微镜(SEM),X射线衍射(XRD)以及氮气吸脱附测试(BET)等对产物形貌、组成和结构进行了表征。实验结果显示,采用模板法结合化学聚合法可以合成形貌均一、单分散的空心碳球;其直径约为500 nm,壁厚约为30 nm。进一步采用熔融灌入法可以得到空心碳球负载二硫化硒复合材料。将所制备复合材料组装成电池进行电化学性能测试,与原始二硫化硒块体材料相比,SeS_2@HCS复合材料具有更高的初始容量(100 m A?g^(-1)电流密度下,初始放电容量为956 m Ah?g^(-1))和更长的循环寿命(100 m A?g^(-1)电流密度下,循环200圈),同时显示出更优异的倍率性能。研究结果表明该复合材料是一种具有应用前景的新型锂离子电池正极材料。展开更多
Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily ac...Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2)electroreduction remains challenging yet indispensable.In this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx sites.Benefiting from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be ensured.As a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2)and a Faradaic efficiency of 93.0%at-1.0 V vs.RHE,outperforming those of its PEI-free analog.Apart from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term stability.The findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2)reduction.Furthermore,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.展开更多
穿梭效应导致锂硫电池(LSBs)充放电性能衰减、寿命短,阻碍其成功进入商业化。穿梭效应的抑制策略可阻止聚硫负离子移动和减少可溶性Li_(2)Sx浓度。前者对穿梭效应的抑制存在饱和现象,因此在优化锂硫电池正极材料中,引入过渡金属催化剂...穿梭效应导致锂硫电池(LSBs)充放电性能衰减、寿命短,阻碍其成功进入商业化。穿梭效应的抑制策略可阻止聚硫负离子移动和减少可溶性Li_(2)Sx浓度。前者对穿梭效应的抑制存在饱和现象,因此在优化锂硫电池正极材料中,引入过渡金属催化剂加速聚硫化锂的转化是进一步抑制穿梭效应、提高电池寿命的可行方案。通过优化碳复合材料设计制备了氧化亚锰(MnO)@空心碳球复合材料,两面三点(物理:多孔笼状结构的阻碍;化学:极性材料共价吸附和催化剂加速多硫化锂转化)协同抑制穿梭效应。结果表明,该优化材料能有效提升锂硫电池充放电性能、改善循环寿命,且倍率性能良好。在0.5 C倍率下,其初始放电比容量达到1009 m A·h/g,经过200次循环之后,其比容量为853 m A·h/g,容量保持率达到84.5%。展开更多
采用高温石墨化处理和原位沉淀法,首次将高度石墨化空心碳球(HGS)与纳米锗(Ge)球复合制备锂离子电池负极材料。所制备复合材料中Ge的负载量为57.9%,表现出较高的循环稳定性和优异的倍率性能,特别是具有较高的首次库仑效率。在0.2 C下,...采用高温石墨化处理和原位沉淀法,首次将高度石墨化空心碳球(HGS)与纳米锗(Ge)球复合制备锂离子电池负极材料。所制备复合材料中Ge的负载量为57.9%,表现出较高的循环稳定性和优异的倍率性能,特别是具有较高的首次库仑效率。在0.2 C下,首次充放电比容量分别为1 427.4和1 153.3 m Ah/g,首次库仑效率高达80.8%;在4 C倍率下可逆比容量可达600 m Ah/g;经过100次循环后,平均每次循环容量衰减量小于0.46%。展开更多
文摘制备了一种空心碳球负载二硫化硒(SeS_2@HCS)复合材料作为锂离子电池正极材料。通过扫描电子显微镜(SEM),X射线衍射(XRD)以及氮气吸脱附测试(BET)等对产物形貌、组成和结构进行了表征。实验结果显示,采用模板法结合化学聚合法可以合成形貌均一、单分散的空心碳球;其直径约为500 nm,壁厚约为30 nm。进一步采用熔融灌入法可以得到空心碳球负载二硫化硒复合材料。将所制备复合材料组装成电池进行电化学性能测试,与原始二硫化硒块体材料相比,SeS_2@HCS复合材料具有更高的初始容量(100 m A?g^(-1)电流密度下,初始放电容量为956 m Ah?g^(-1))和更长的循环寿命(100 m A?g^(-1)电流密度下,循环200圈),同时显示出更优异的倍率性能。研究结果表明该复合材料是一种具有应用前景的新型锂离子电池正极材料。
文摘Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2)electroreduction remains challenging yet indispensable.In this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx sites.Benefiting from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be ensured.As a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2)and a Faradaic efficiency of 93.0%at-1.0 V vs.RHE,outperforming those of its PEI-free analog.Apart from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term stability.The findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2)reduction.Furthermore,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.
文摘穿梭效应导致锂硫电池(LSBs)充放电性能衰减、寿命短,阻碍其成功进入商业化。穿梭效应的抑制策略可阻止聚硫负离子移动和减少可溶性Li_(2)Sx浓度。前者对穿梭效应的抑制存在饱和现象,因此在优化锂硫电池正极材料中,引入过渡金属催化剂加速聚硫化锂的转化是进一步抑制穿梭效应、提高电池寿命的可行方案。通过优化碳复合材料设计制备了氧化亚锰(MnO)@空心碳球复合材料,两面三点(物理:多孔笼状结构的阻碍;化学:极性材料共价吸附和催化剂加速多硫化锂转化)协同抑制穿梭效应。结果表明,该优化材料能有效提升锂硫电池充放电性能、改善循环寿命,且倍率性能良好。在0.5 C倍率下,其初始放电比容量达到1009 m A·h/g,经过200次循环之后,其比容量为853 m A·h/g,容量保持率达到84.5%。
基金supported by National Natural Science Foundation of China(22108306)Taishan Scholars Program of Shandong Province(tsqn201909065)Shandong Provincial Natural Science Foundation(ZR2021YQ15,ZR2020QB174)。
文摘采用高温石墨化处理和原位沉淀法,首次将高度石墨化空心碳球(HGS)与纳米锗(Ge)球复合制备锂离子电池负极材料。所制备复合材料中Ge的负载量为57.9%,表现出较高的循环稳定性和优异的倍率性能,特别是具有较高的首次库仑效率。在0.2 C下,首次充放电比容量分别为1 427.4和1 153.3 m Ah/g,首次库仑效率高达80.8%;在4 C倍率下可逆比容量可达600 m Ah/g;经过100次循环后,平均每次循环容量衰减量小于0.46%。
