为了提高锂硫电池电化学性能,针对其面临的多硫化锂穿梭问题,本文以还原氧化石墨烯(rGO)为生长基质,结合四硫化钒(VS4)与多价态钼(Mo)带来的吸附性能及硫空位修复优势,采用水热法制备了复合材料VS4/Mo@rGO作为锂硫正极材料中的载体组分...为了提高锂硫电池电化学性能,针对其面临的多硫化锂穿梭问题,本文以还原氧化石墨烯(rGO)为生长基质,结合四硫化钒(VS4)与多价态钼(Mo)带来的吸附性能及硫空位修复优势,采用水热法制备了复合材料VS4/Mo@rGO作为锂硫正极材料中的载体组分,它不仅有更多的活性点位缓解穿梭效应,还能减少VS4本征硫空位的体积膨胀,为克制电解液中多硫化锂的溶解及极片失效粉化提供了较大帮助。通过熔融扩散法载硫后,该正极在负载量8 mg cm−2、0.3 C时首次放电915 mAh g−1,在10 mg cm−2负载电极的倍率测试中,其放电比容量中值仍有513 mAh g−1,整体倍率性能远高于rGO/S和CB@rGO/S。展开更多
采用一步水热法并添加表面活性剂聚乙二醇400制备出花球状二硫化钒,利用X射线粉末衍射仪、场发射扫描电子显微镜等方法对产物的物相和形貌进行了表征.观测生长过程发现花球状二硫化钒由若干六边形二硫化钒纳米片堆叠穿插组成,该花球状...采用一步水热法并添加表面活性剂聚乙二醇400制备出花球状二硫化钒,利用X射线粉末衍射仪、场发射扫描电子显微镜等方法对产物的物相和形貌进行了表征.观测生长过程发现花球状二硫化钒由若干六边形二硫化钒纳米片堆叠穿插组成,该花球状结构使材料拥有较高的比表面积及出色的结构稳定性.将花球状二硫化钒用于锂离子电池正极材料测试,结果表明花球状二硫化钒在电压区间为1～3 V,电流密度为200 m A·g^(-1)时具有出色的循环稳定性且循环50周之后容量可达450 m Ah·g^(-1).展开更多
锂硫电池因其高的理论比容量与能量密度而被视为最具前景的储能电池之一,但锂硫电池中活性物质硫及其放电产物Li_(2)S的低导电性、充放电过程产生的中间产物的穿梭效应、缓慢的硫氧化还原动力学等问题造成了严重的容量衰减,限制了其实...锂硫电池因其高的理论比容量与能量密度而被视为最具前景的储能电池之一,但锂硫电池中活性物质硫及其放电产物Li_(2)S的低导电性、充放电过程产生的中间产物的穿梭效应、缓慢的硫氧化还原动力学等问题造成了严重的容量衰减,限制了其实际应用。本文通过一步水热法合成3种不同的钒基硫化物@MXene异质结构催化剂,并将其应用于锂硫电池正极宿主。结果表明相比于VS_(4)@MXene和V_(5)S_(8)@MXene,VS_(2)@MXene具有更大的比表面积与电化学活性面积,为锂硫电池提供了更多的活性位点,从而提高电化学反应动力学。本文实验与密度泛函理论(Density Functional Theory,DFT)计算结果表明,VS_(2)@MXene具有更强的多硫化物吸附能力与电子导电性,有效地缓解了多硫化物的穿梭效应并提高了硫的利用率。以S/VS_(2)@MXene为正极的锂硫电池,在1 C的电流密度下实现了815.4 m Ah·g^(-1)的首圈放电比容量,并在400圈循环后,仍然能保持在645.4 m Ah·g^(-1)的可逆比容量。本文为锂硫电池中钒基硫化物正极催化材料的选择提供了一定的思路。展开更多
Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelect...Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water splitting.However,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)kinetics.In this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)photoanode.The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co S.This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.展开更多
文摘为了提高锂硫电池电化学性能,针对其面临的多硫化锂穿梭问题,本文以还原氧化石墨烯(rGO)为生长基质,结合四硫化钒(VS4)与多价态钼(Mo)带来的吸附性能及硫空位修复优势,采用水热法制备了复合材料VS4/Mo@rGO作为锂硫正极材料中的载体组分,它不仅有更多的活性点位缓解穿梭效应,还能减少VS4本征硫空位的体积膨胀,为克制电解液中多硫化锂的溶解及极片失效粉化提供了较大帮助。通过熔融扩散法载硫后,该正极在负载量8 mg cm−2、0.3 C时首次放电915 mAh g−1,在10 mg cm−2负载电极的倍率测试中,其放电比容量中值仍有513 mAh g−1,整体倍率性能远高于rGO/S和CB@rGO/S。
文摘采用一步水热法并添加表面活性剂聚乙二醇400制备出花球状二硫化钒,利用X射线粉末衍射仪、场发射扫描电子显微镜等方法对产物的物相和形貌进行了表征.观测生长过程发现花球状二硫化钒由若干六边形二硫化钒纳米片堆叠穿插组成,该花球状结构使材料拥有较高的比表面积及出色的结构稳定性.将花球状二硫化钒用于锂离子电池正极材料测试,结果表明花球状二硫化钒在电压区间为1～3 V,电流密度为200 m A·g^(-1)时具有出色的循环稳定性且循环50周之后容量可达450 m Ah·g^(-1).
文摘锂硫电池因其高的理论比容量与能量密度而被视为最具前景的储能电池之一,但锂硫电池中活性物质硫及其放电产物Li_(2)S的低导电性、充放电过程产生的中间产物的穿梭效应、缓慢的硫氧化还原动力学等问题造成了严重的容量衰减,限制了其实际应用。本文通过一步水热法合成3种不同的钒基硫化物@MXene异质结构催化剂,并将其应用于锂硫电池正极宿主。结果表明相比于VS_(4)@MXene和V_(5)S_(8)@MXene,VS_(2)@MXene具有更大的比表面积与电化学活性面积,为锂硫电池提供了更多的活性位点,从而提高电化学反应动力学。本文实验与密度泛函理论(Density Functional Theory,DFT)计算结果表明,VS_(2)@MXene具有更强的多硫化物吸附能力与电子导电性,有效地缓解了多硫化物的穿梭效应并提高了硫的利用率。以S/VS_(2)@MXene为正极的锂硫电池,在1 C的电流密度下实现了815.4 m Ah·g^(-1)的首圈放电比容量,并在400圈循环后,仍然能保持在645.4 m Ah·g^(-1)的可逆比容量。本文为锂硫电池中钒基硫化物正极催化材料的选择提供了一定的思路。
文摘Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water splitting.However,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)kinetics.In this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)photoanode.The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co S.This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.
