采用水热法合成纳米Li Fe PO4材料并研究了反应溶液p H值和温度对Li Fe PO4材料颗粒形貌、微观结构和电化学性能的影响。控制Li∶Fe∶P摩尔比为3∶1∶1,按照先混合Li OH与H3PO4溶液后加入Fe SO4溶液的投料顺序,在溶液p H值为6.0以上可...采用水热法合成纳米Li Fe PO4材料并研究了反应溶液p H值和温度对Li Fe PO4材料颗粒形貌、微观结构和电化学性能的影响。控制Li∶Fe∶P摩尔比为3∶1∶1,按照先混合Li OH与H3PO4溶液后加入Fe SO4溶液的投料顺序,在溶液p H值为6.0以上可以得到结晶度好且比容量较高的纳米级Li Fe PO4材料。p H为6.0和180℃条件下得到的是Li Fe PO4纳米薄片,调整反应溶液p H值为中性和弱碱性,或控制反应温度在140℃以下或者200℃以上,Li Fe PO4材料可能是方形或者形貌不规则的纳米颗粒。电化学测试结果表明,颗粒形貌方形或者不规则的Li Fe PO4材料大电流放电性能优于薄片状纳米材料。展开更多
A series of manganese spinels LiMn2-yMeyO4 （Me = Li, A1, Mg） were prepared and examined by XRD and electrochemical methods. The spinels doped with Li or high content of A1 can exhibit discharge capacity in the 5 V r...A series of manganese spinels LiMn2-yMeyO4 （Me = Li, A1, Mg） were prepared and examined by XRD and electrochemical methods. The spinels doped with Li or high content of A1 can exhibit discharge capacity in the 5 V region, but spinels doped with Mg do not exhibit any 5 V discharge capacity. It is also observed that the 5 V discharge capacity of Li/A1 doped spinels will be greatly suppressed once calcinated at temperatures above 900 ℃ in preparation. It is suggested that the 5 V discharge capacity of Li/A1 doped spinels may be originated from the special chemical/structural characteristics of spinel phases containing Li or high content of A1 prepared at temperatures below 900 ℃.展开更多
LiFePO4 nanorods were facilely synthesized under hydrothermal condition. The crystalline structure and particle morphology of LiFePO4 powders were characterized by X-ray diffraction （XRD）, and field emission scannin...LiFePO4 nanorods were facilely synthesized under hydrothermal condition. The crystalline structure and particle morphology of LiFePO4 powders were characterized by X-ray diffraction （XRD）, and field emission scanning electron microscopy （FE-SEM）. The electrochemical properties of LiFePO4/Li cells were investigated by galvanostatic test and cyclic voltammetry （CV）. The XRD result demonstrated LiFePO4 powder had an orthorhombic structure with a space group of Pnma. The synthesized LiFePO4 nanorods exhibited a first discharge capacity of 155 mAh·g-1 （91% of theorectical capacity） close to the theorectical capacity of LiFePO4 （170 mAh·g-1） at 0.1 C.展开更多
TiNb2O7的理论比容量高达280 mA h g^-1,是一类有前景的锂离子电容器负极材料.然而其较差的电子导电性严重限制了其倍率性能的提升.在本文中,我们在柔性碳布表面直接生长3D交联的TiNb2O7纳米棒多孔负极,并将其首次应用于柔性锂离子电容...TiNb2O7的理论比容量高达280 mA h g^-1,是一类有前景的锂离子电容器负极材料.然而其较差的电子导电性严重限制了其倍率性能的提升.在本文中,我们在柔性碳布表面直接生长3D交联的TiNb2O7纳米棒多孔负极,并将其首次应用于柔性锂离子电容器;碳布的高导电性,单晶纳米棒结构较短的离子/电子传输路径以及良好的结构稳定性,有效提高了材料的倍率性能和循环稳定性.研究表明,Ti Nb2O7负极表现出优异的倍率性能(从1到40 C,容量保持率高达66.3%),出色的循环稳定性(>2000圈),以及良好的柔韧性(连续弯曲500次后容量无损失).此外,将无粘结剂的Ti Nb2O7负极和商用活性炭正极搭配成锂离子电容器,展现出了较高的质量和体积能量/功率密度(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 m W h cm^-3/419.3 mW cm^-3),优于先前报道的混合超级电容器,同时该器件可以在180°弯曲状态下为LED灯供电.展开更多
文摘采用水热法合成纳米Li Fe PO4材料并研究了反应溶液p H值和温度对Li Fe PO4材料颗粒形貌、微观结构和电化学性能的影响。控制Li∶Fe∶P摩尔比为3∶1∶1,按照先混合Li OH与H3PO4溶液后加入Fe SO4溶液的投料顺序,在溶液p H值为6.0以上可以得到结晶度好且比容量较高的纳米级Li Fe PO4材料。p H为6.0和180℃条件下得到的是Li Fe PO4纳米薄片,调整反应溶液p H值为中性和弱碱性,或控制反应温度在140℃以下或者200℃以上,Li Fe PO4材料可能是方形或者形貌不规则的纳米颗粒。电化学测试结果表明,颗粒形貌方形或者不规则的Li Fe PO4材料大电流放电性能优于薄片状纳米材料。
基金Funded partly by the Fundamental Research Funds for the Central Universities (No.WHUT-2012-Ia-029)the Foundation of the Ministry of Education of China for Returned Scholars (No.2007-24)
文摘A series of manganese spinels LiMn2-yMeyO4 （Me = Li, A1, Mg） were prepared and examined by XRD and electrochemical methods. The spinels doped with Li or high content of A1 can exhibit discharge capacity in the 5 V region, but spinels doped with Mg do not exhibit any 5 V discharge capacity. It is also observed that the 5 V discharge capacity of Li/A1 doped spinels will be greatly suppressed once calcinated at temperatures above 900 ℃ in preparation. It is suggested that the 5 V discharge capacity of Li/A1 doped spinels may be originated from the special chemical/structural characteristics of spinel phases containing Li or high content of A1 prepared at temperatures below 900 ℃.
基金Funded by the National Natural Science Foundation of China(No. 20803055)the Self-determined and Innovation Nesearch Funds of WUT (2010-1G-043)
文摘LiFePO4 nanorods were facilely synthesized under hydrothermal condition. The crystalline structure and particle morphology of LiFePO4 powders were characterized by X-ray diffraction （XRD）, and field emission scanning electron microscopy （FE-SEM）. The electrochemical properties of LiFePO4/Li cells were investigated by galvanostatic test and cyclic voltammetry （CV）. The XRD result demonstrated LiFePO4 powder had an orthorhombic structure with a space group of Pnma. The synthesized LiFePO4 nanorods exhibited a first discharge capacity of 155 mAh·g-1 （91% of theorectical capacity） close to the theorectical capacity of LiFePO4 （170 mAh·g-1） at 0.1 C.
基金supported by the National Natural Science Foundation of China (51672205, 21673169 and 51972257)the National Key R&D Program of China (2016YFA0202602)the Natural Science Foundation of Hubei Province (2018CFB581)
文摘TiNb2O7的理论比容量高达280 mA h g^-1,是一类有前景的锂离子电容器负极材料.然而其较差的电子导电性严重限制了其倍率性能的提升.在本文中,我们在柔性碳布表面直接生长3D交联的TiNb2O7纳米棒多孔负极,并将其首次应用于柔性锂离子电容器;碳布的高导电性,单晶纳米棒结构较短的离子/电子传输路径以及良好的结构稳定性,有效提高了材料的倍率性能和循环稳定性.研究表明,Ti Nb2O7负极表现出优异的倍率性能(从1到40 C,容量保持率高达66.3%),出色的循环稳定性(>2000圈),以及良好的柔韧性(连续弯曲500次后容量无损失).此外,将无粘结剂的Ti Nb2O7负极和商用活性炭正极搭配成锂离子电容器,展现出了较高的质量和体积能量/功率密度(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 m W h cm^-3/419.3 mW cm^-3),优于先前报道的混合超级电容器,同时该器件可以在180°弯曲状态下为LED灯供电.
