Some special fields,such as deep-sea exploration,require batteries and their electrode materials to withstand extremely high pressure.As the cathode material has the highest energy density,Li-excess Mn-based materials...Some special fields,such as deep-sea exploration,require batteries and their electrode materials to withstand extremely high pressure.As the cathode material has the highest energy density,Li-excess Mn-based materials are also likely to be utilized in such an environment.However,the effect of pressure on the crystal structure and migration barrier of this kind of material is still not clear at present.Therefore,in this study,we investigate the properties of the matrix material of Li-excess Mn-based material,Li_(2)MnO_(3),under high pressure.The equation of state,bulk modulus,and steady-state volume of Li_(2)MnO_(3) are predicted by the method of first principles calculation.The calculations of unit cells at different pressures reveal that the cell parameters suffer anisotropic compression under high pressure.During compression,Li-O bond is more easily compressed than Mn-O bond.The results from the climbing image nudged elastic band(CINEB)method show that the energy barrier of Li^(+)migration in the lithium layer increases with pressure increasing.Our study can provide useful information for utilizing Li-excess Mn-based materials under high pressure.展开更多
商业化的多壁碳纳米管通常是相互缠绕且紧密团聚,长度高达数十微米,不利于电解液离子的传输,尤其是难以利用碳纳米管内部空间。本文通过简单的化学氧化方法从横向和纵向同时裁剪多壁碳纳米管,形成弯曲的石墨烯带(CGS),将其浸入0.1 mol L...商业化的多壁碳纳米管通常是相互缠绕且紧密团聚,长度高达数十微米,不利于电解液离子的传输,尤其是难以利用碳纳米管内部空间。本文通过简单的化学氧化方法从横向和纵向同时裁剪多壁碳纳米管,形成弯曲的石墨烯带(CGS),将其浸入0.1 mol L^(-1)高锰酸钾溶液中,合成了CGS-MnO_(2)复合材料。利用FESEM、TEM、XRD、Raman对CGS-MnO_(2)的形貌和结构进行详细表征,结果表明无定形MnO_(2)成功地锚定在CGS的表面。在三电极体系中,CGS-MnO_(2)在2 mV s^(-1)的扫速下电容值达到236 F g^(-1),甚至在100 mV s^(-1)下电容仍能保持127 F g^(-1),远高于对比样品的电容值,例如MWCNTs(15 F g^(-1)),CGS(88 F g^(-1))和MWCNTs-MnO_(2)复合材料(111 F g^(-1))。此外,该材料还表现出优异的循环稳定性能,循环1000次后电容仍然保持97%。展开更多
In this work, Al-substituted a-Co（OH）2/GO composites with supercapacitive properties were prepared by chemical co-precipitated method in which cobalt nitrate and aluminum nitrate were used as the raw material, and g...In this work, Al-substituted a-Co（OH）2/GO composites with supercapacitive properties were prepared by chemical co-precipitated method in which cobalt nitrate and aluminum nitrate were used as the raw material, and graphite oxide was employed as carrier. The as-prepared materials were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and fourier transform infrared spectroscopy （FF-IR）. Cyclic voltammetry （CV） and galvanostatic charge/discharge measurements showed that the Al-substituted a-Co（OH）2/GO electrode material had excellent electrochemical capacitance. The specific capacitance of 1137 F·g-11 was achieved in 6 mol/L KOH solution at a current density of 1 A·g-1 within a potential range of 0-0.5 V. Moreover, only 12% losses of the initial specific capacitance were found after 500 cycles at a current density of 1 A·g-1.展开更多
基金Project supported by the Research on High Power Flexible Battery in All Sea Depth,China (Grant No.2020-XXXXXX-246-00)。
文摘Some special fields,such as deep-sea exploration,require batteries and their electrode materials to withstand extremely high pressure.As the cathode material has the highest energy density,Li-excess Mn-based materials are also likely to be utilized in such an environment.However,the effect of pressure on the crystal structure and migration barrier of this kind of material is still not clear at present.Therefore,in this study,we investigate the properties of the matrix material of Li-excess Mn-based material,Li_(2)MnO_(3),under high pressure.The equation of state,bulk modulus,and steady-state volume of Li_(2)MnO_(3) are predicted by the method of first principles calculation.The calculations of unit cells at different pressures reveal that the cell parameters suffer anisotropic compression under high pressure.During compression,Li-O bond is more easily compressed than Mn-O bond.The results from the climbing image nudged elastic band(CINEB)method show that the energy barrier of Li^(+)migration in the lithium layer increases with pressure increasing.Our study can provide useful information for utilizing Li-excess Mn-based materials under high pressure.
文摘商业化的多壁碳纳米管通常是相互缠绕且紧密团聚,长度高达数十微米,不利于电解液离子的传输,尤其是难以利用碳纳米管内部空间。本文通过简单的化学氧化方法从横向和纵向同时裁剪多壁碳纳米管,形成弯曲的石墨烯带(CGS),将其浸入0.1 mol L^(-1)高锰酸钾溶液中,合成了CGS-MnO_(2)复合材料。利用FESEM、TEM、XRD、Raman对CGS-MnO_(2)的形貌和结构进行详细表征,结果表明无定形MnO_(2)成功地锚定在CGS的表面。在三电极体系中,CGS-MnO_(2)在2 mV s^(-1)的扫速下电容值达到236 F g^(-1),甚至在100 mV s^(-1)下电容仍能保持127 F g^(-1),远高于对比样品的电容值,例如MWCNTs(15 F g^(-1)),CGS(88 F g^(-1))和MWCNTs-MnO_(2)复合材料(111 F g^(-1))。此外,该材料还表现出优异的循环稳定性能,循环1000次后电容仍然保持97%。
基金funded by the National Key Research and Development Program of China (2016YFC0300200)the National Natural Science Foundation of China (21975229)the Natural Science Foundation of Zhejiang Province (Y19B060003)
基金Project supported by the National Natural Science Foundation of China （Nos. 20963009, 21163017）, Gansu Science and Technology Committee （No. 0803RJA005） and the postgraduate advisor program of Provincial Education Department of Gansu.
文摘In this work, Al-substituted a-Co（OH）2/GO composites with supercapacitive properties were prepared by chemical co-precipitated method in which cobalt nitrate and aluminum nitrate were used as the raw material, and graphite oxide was employed as carrier. The as-prepared materials were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and fourier transform infrared spectroscopy （FF-IR）. Cyclic voltammetry （CV） and galvanostatic charge/discharge measurements showed that the Al-substituted a-Co（OH）2/GO electrode material had excellent electrochemical capacitance. The specific capacitance of 1137 F·g-11 was achieved in 6 mol/L KOH solution at a current density of 1 A·g-1 within a potential range of 0-0.5 V. Moreover, only 12% losses of the initial specific capacitance were found after 500 cycles at a current density of 1 A·g-1.
