硒(Se)因其较高的体积比容量(3253 mAh cm^(-3))和电子电导率(1×10^(-5)S m^(-1))而成为新一代锂硒(Li-Se)电池储能材料。针对其反应过程中体积膨胀较大、容量衰减较快以及活性物质利用率低等问题,本研究通过在碳布(CC)上生长二维Z...硒(Se)因其较高的体积比容量(3253 mAh cm^(-3))和电子电导率(1×10^(-5)S m^(-1))而成为新一代锂硒(Li-Se)电池储能材料。针对其反应过程中体积膨胀较大、容量衰减较快以及活性物质利用率低等问题,本研究通过在碳布(CC)上生长二维Zn基金属有机框架(ZIF-L)并碳化,设计了一种ZIF-L衍生氮掺杂碳纳米片/硒自支撑复合材料(Se@NC/CC)用于锂硒电池研究。ZIF-L碳化形成的氮掺杂碳纳米片中丰富的微孔结构有效缓解了反应过程中的体积膨胀,掺杂N原子有利于吸附反应过程中的Li2Se,减少活性物质损失。特别地,Se@NC/CC电极中Se和C之间存在强的化学键作用,在一定程度上也可以减少活性物质损失,提高整体性能稳定性。电化学测试表明,在0.5C(1.0C=675 mAh g^(-1))电流密度下,Se@NC/CC电极的初始放电比容量为574 mAh g^(-1),展现出高初始放电比容量;电流密度为2.0C时,初始放电比容量为453.3 mAh g^(-1),循环500圈后仍然具有406.2 mAh g^(-1)的容量;同时也表现出了良好的倍率性能,与文献报道相比有较明显的优势。本研究设计的柔性自支撑硒电极为先进碱金属-硒电池的硒宿主材料设计提供了新的研究思路。展开更多
以甘氨酸作为碳源,KOH为活化剂,通过直接碳化/活化,制备了氮掺杂的多孔碳材料。继与硒高温融混,制得多孔碳/硒复合材料。X-射线衍射和氮气吸脱附测试结果表明多孔碳主要呈无定型结构,并具有以微孔为主的多孔结构;硒则均匀地分散于多孔...以甘氨酸作为碳源,KOH为活化剂,通过直接碳化/活化,制备了氮掺杂的多孔碳材料。继与硒高温融混,制得多孔碳/硒复合材料。X-射线衍射和氮气吸脱附测试结果表明多孔碳主要呈无定型结构,并具有以微孔为主的多孔结构;硒则均匀地分散于多孔碳的微孔中。以其作为正极的锂硒电池,在电流密度为0.2C时,其首次可逆放电比容量为378.5 m Ah·g-1,经过100次循环,放电比容量仍可以保持在321 m Ah·g-1,表现出了良好的电化学性能。展开更多
Li metal possesses a high theoretical specific capacity,high electronic conductivity,and a low electrochemical potential,making it a promising anode material for building next-generation rechargeable metal batteries.I...Li metal possesses a high theoretical specific capacity,high electronic conductivity,and a low electrochemical potential,making it a promising anode material for building next-generation rechargeable metal batteries.In case conventional liquid electrolytes were used,and the anode using Li metal has been hindered by unstable(electro)chemistry at Li/electrolyte interface and the accompanied dendrite issue.Specifically,for the Li-Se batteries,the dissolution and shuttle of polyselenide intermediates lead to the deposition of poorly-conductive species on the anode,which further aggravates the chemical environment at the anode.In this work,we proposed to stabilize the Li-Se electrochemistry by constructing a gel polymer electrolyte via in situ gelations of conventional ether-based electrolytes at room temperature.The results demonstrate that the in situ gelated electrolyte helps to build electrochemically stable electrode/electrolyte interfaces and promote the efficient transfer of charge carriers across the interface.Compared with the liquid electrolytes,the gelated electrolyte shows improved chemical compatibility with the Li metal anode,which effectively alleviates the unfavorable side reactions and dendrite formation at the anode/electrolyte interface,and the polyselenide shuttle from the cathode to the anode.As a result,the Li-Se battery shows a higher Coulombic efficiency and improved cycling performance.展开更多
文摘硒(Se)因其较高的体积比容量(3253 mAh cm^(-3))和电子电导率(1×10^(-5)S m^(-1))而成为新一代锂硒(Li-Se)电池储能材料。针对其反应过程中体积膨胀较大、容量衰减较快以及活性物质利用率低等问题,本研究通过在碳布(CC)上生长二维Zn基金属有机框架(ZIF-L)并碳化,设计了一种ZIF-L衍生氮掺杂碳纳米片/硒自支撑复合材料(Se@NC/CC)用于锂硒电池研究。ZIF-L碳化形成的氮掺杂碳纳米片中丰富的微孔结构有效缓解了反应过程中的体积膨胀,掺杂N原子有利于吸附反应过程中的Li2Se,减少活性物质损失。特别地,Se@NC/CC电极中Se和C之间存在强的化学键作用,在一定程度上也可以减少活性物质损失,提高整体性能稳定性。电化学测试表明,在0.5C(1.0C=675 mAh g^(-1))电流密度下,Se@NC/CC电极的初始放电比容量为574 mAh g^(-1),展现出高初始放电比容量;电流密度为2.0C时,初始放电比容量为453.3 mAh g^(-1),循环500圈后仍然具有406.2 mAh g^(-1)的容量;同时也表现出了良好的倍率性能,与文献报道相比有较明显的优势。本研究设计的柔性自支撑硒电极为先进碱金属-硒电池的硒宿主材料设计提供了新的研究思路。
文摘以甘氨酸作为碳源,KOH为活化剂,通过直接碳化/活化,制备了氮掺杂的多孔碳材料。继与硒高温融混,制得多孔碳/硒复合材料。X-射线衍射和氮气吸脱附测试结果表明多孔碳主要呈无定型结构,并具有以微孔为主的多孔结构;硒则均匀地分散于多孔碳的微孔中。以其作为正极的锂硒电池,在电流密度为0.2C时,其首次可逆放电比容量为378.5 m Ah·g-1,经过100次循环,放电比容量仍可以保持在321 m Ah·g-1,表现出了良好的电化学性能。
基金This work was supported by the National Key R&D Program of China(No.2016YFA0202500)the National Natural Science Foundation of China(Nos.21975266,21805062)and the Beijing National Laboratory for Molecular Sciences,China(No.BNLMS-CXXM-201906).
文摘Li metal possesses a high theoretical specific capacity,high electronic conductivity,and a low electrochemical potential,making it a promising anode material for building next-generation rechargeable metal batteries.In case conventional liquid electrolytes were used,and the anode using Li metal has been hindered by unstable(electro)chemistry at Li/electrolyte interface and the accompanied dendrite issue.Specifically,for the Li-Se batteries,the dissolution and shuttle of polyselenide intermediates lead to the deposition of poorly-conductive species on the anode,which further aggravates the chemical environment at the anode.In this work,we proposed to stabilize the Li-Se electrochemistry by constructing a gel polymer electrolyte via in situ gelations of conventional ether-based electrolytes at room temperature.The results demonstrate that the in situ gelated electrolyte helps to build electrochemically stable electrode/electrolyte interfaces and promote the efficient transfer of charge carriers across the interface.Compared with the liquid electrolytes,the gelated electrolyte shows improved chemical compatibility with the Li metal anode,which effectively alleviates the unfavorable side reactions and dendrite formation at the anode/electrolyte interface,and the polyselenide shuttle from the cathode to the anode.As a result,the Li-Se battery shows a higher Coulombic efficiency and improved cycling performance.
