In order to confirm the optimal Li content of Li-rich Mn-based cathode materials(a fixed mole ratio of Mn to Ni to Co is0.6:0.2:0.2),Li1+x(Mn0.6Ni0.2Co0.2)1-xO2(x=0,0.1,0.2,0.3)composites were obtained,which had a typ...In order to confirm the optimal Li content of Li-rich Mn-based cathode materials(a fixed mole ratio of Mn to Ni to Co is0.6:0.2:0.2),Li1+x(Mn0.6Ni0.2Co0.2)1-xO2(x=0,0.1,0.2,0.3)composites were obtained,which had a typical layered structure with R3m and C2/m space group observed from X-ray powder diffraction(XRD).Electron microscopy micrograph(SEM)reveals that the particle sizes in the range of0.4-1.1μm increase with an increase of x value.Li1.2(Mn0.6Ni0.2Co0.2)0.8O2sample delivers a larger initial discharge capacity of275.7mA·h/g at the current density of20mA/g in the potential range of2.0-4.8V,while Li1.1(Mn0.6Ni0.2Co0.2)0.9O2shows a better cycle performance with a capacity retention of93.8%at0.2C after50cycles,showing better reaction kinetics of lithium ion insertion and extraction.展开更多
Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation me...Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g^(-1) over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g^(-1) at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.展开更多
Mg3（PO4）2-coated Li1.05Ni1/3Mn1/33Co1/3O2 cathode materials were synthesized via co-precipitation method. The morphology, structure, electrochemical performance and thermal stability were characterized by scanning e...Mg3（PO4）2-coated Li1.05Ni1/3Mn1/33Co1/3O2 cathode materials were synthesized via co-precipitation method. The morphology, structure, electrochemical performance and thermal stability were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, cyclic voltammetry（CV）, electrochemical impedance spectroscopy（EIS）, charge/discharge cycling and differential scanning calorimeter （DSC）. SEM analysis shows that Mg3（PO4）2-coating changes the morphologies of their particles and increases the grains size. XRD and CV results show that Mg3（PO4）2-coating powder is homogeneous and has better layered structure than the bare one. Mg3（PO4）2-coating improved high rate discharge capacity and cycle-life performance. The reason why the cycling performance of Mg3（PO4）2-coated sample at 55 ℃ was better than that of room temperature was the increasing of lithium-ion diffusion rate and charge transfer rate with temperature rising. Mg3（PO4）2-coating improved the cathode thermal stability, and the result was consistent with thermal abuse tests using Li-ion cells： the Mg3（PO4）2 coated Li1.05Ni1/3Mn1/3Co1/3O2 cathode did not exhibit thermal runaway with smoke and explosion, in contrast to the cells containing the bare Li1.05Ni1/3Mn1/3Co1/3O2.展开更多
The cathode materials LiNixCo1-xO2 (0≤x≤1) for lithium ion battery were prepared in solid phase . The effects of synthesis temperature , the time of heat treatment and also the ratio of raw materials on products wer...The cathode materials LiNixCo1-xO2 (0≤x≤1) for lithium ion battery were prepared in solid phase . The effects of synthesis temperature , the time of heat treatment and also the ratio of raw materials on products were discussed . The residts showed that the products preheated under 600℃ and then sintered under constant, temperature 75017 were better than those sintered under constant temperature 650℃ or 850℃ , and their layer structures were more obvious and their initial capacity was higher . The longer the heat-treating time is , the stronger the products ’ XRD peaks intensity and the better their structures and electrochemical performance are. The samples LiN-ix Co 1-xO2(0≤x≤1) with a perfect structure and electrochemical performance were synthesized. And the products initial capacity was perfect when n(Li) : n( Ni) : n( Co) ℃ 1.15:0.3:0.7,viz. 156.l46mAh/g.展开更多
A layered oxide Li[Ni1/3Mn1/3Co1/3]O2 was synthesized by an oxalate co- precipitation method. The morphology, structural and composition of the as-papered samples synthesized at different calcination temperatures were...A layered oxide Li[Ni1/3Mn1/3Co1/3]O2 was synthesized by an oxalate co- precipitation method. The morphology, structural and composition of the as-papered samples synthesized at different calcination temperatures were investigated. The results indicate that calcination temperature of the sample at 850℃ can improve the integrity of structural significantly. The effect of calcination temperature varying from 750℃ to 950℃ on the electrochemical performance of Li[Ni1/3Mn1/3Co1/3]O2, cathode material of lithiumion batteries, has been investigated. The results show that Li[Ni1/3Mn1/3Co1/3]O2 calcined at 850℃ possesses a higher capacity retention and better rate capability than other samples. The reversible capacity is up to 178.6 mA.h.g-1, and the discharge capacity still remains 176.3 mA-h.g-1 after 30 cycles. Moreover, our strategy provides a simple and highly versatile route in fabricating cathode materials for lithium-ion batteries.展开更多
Cathode materials Li[CoxNiyMn1-x-y]O2 for lithium secondary batteries have been prepared by a new route using layered double hydroxides （LDHs） as a precursor. The resulting layered phase with the α- NaFe02 structur...Cathode materials Li[CoxNiyMn1-x-y]O2 for lithium secondary batteries have been prepared by a new route using layered double hydroxides （LDHs） as a precursor. The resulting layered phase with the α- NaFe02 structure crystallizes in the rhombohedral system, with space group R-3m having an interlayer spacing close to 0.47 nm. X-ray photoelectron spectroscopy （XPS） was used to measure the oxidation states of Co, Ni and Mn. The effects of varying the Co[Ni[Mn ratio on both the structure and electrochemical properties of Li[CoxNiyMn1-x-y]O2 have been investigated by X-ray diffraction and electrochemical tests. The products demonstrated a rather stable cycling behavior, with a reversible capacity of 118 mAh/g for the layered material with Co/Ni/Mn = 1/1/1.展开更多
Porous structure Li[Ni1/3Co1/3Mn1/3]O2 has been synthesized via a facile carbonate co-precipitation method using Li2CO3 as template and lithium-source. The physical and electrochemical properties of the materials were...Porous structure Li[Ni1/3Co1/3Mn1/3]O2 has been synthesized via a facile carbonate co-precipitation method using Li2CO3 as template and lithium-source. The physical and electrochemical properties of the materials were examined by many characterizations including TGA, XRD, SEM, EDS, TEM, BET, CV, EIS and galvanostatic charge-discharge cycling. The results indicate that the as-synthesized materials by this novel method own a well-ordered layered structure a-NaFeO2 [space group： R-3m（166）], porous morphology, and an average primary particle size of about 150 nm. The porous material exhibits larger specific surface area and delivers a high initial capacity of 169.9 mAh·g^-1 at 0.1 C （1 C=180 mA·g ^-1） between 2.7 and 4.3 V, and 126.4, 115.7 mAh.g 1 are still respectively reached at high rate of 10 C and 20 C. After 100 charge-discharge cycles at 1 C, the capacity retention is 93.3%, indicating the excellent cycling stability.展开更多
基金Project(21473258) supported by the National Natural Science Foundation of ChinaProject(13JJ1004) supported by Distinguished Young Scientists of Hunan Province,ChinaProject(NCET-11-0513) supported by Program for the New Century Excellent Talents in University,China
文摘In order to confirm the optimal Li content of Li-rich Mn-based cathode materials(a fixed mole ratio of Mn to Ni to Co is0.6:0.2:0.2),Li1+x(Mn0.6Ni0.2Co0.2)1-xO2(x=0,0.1,0.2,0.3)composites were obtained,which had a typical layered structure with R3m and C2/m space group observed from X-ray powder diffraction(XRD).Electron microscopy micrograph(SEM)reveals that the particle sizes in the range of0.4-1.1μm increase with an increase of x value.Li1.2(Mn0.6Ni0.2Co0.2)0.8O2sample delivers a larger initial discharge capacity of275.7mA·h/g at the current density of20mA/g in the potential range of2.0-4.8V,while Li1.1(Mn0.6Ni0.2Co0.2)0.9O2shows a better cycle performance with a capacity retention of93.8%at0.2C after50cycles,showing better reaction kinetics of lithium ion insertion and extraction.
基金financially supported by the National Natural Science Foundation of China (No. 51372136)the NSFC-Guangdong United Fund (No. U1401246)
文摘Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g^(-1) over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g^(-1) at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.
基金Funded by the National Natural Science Foundation of China (No. 20273047)
文摘Mg3（PO4）2-coated Li1.05Ni1/3Mn1/33Co1/3O2 cathode materials were synthesized via co-precipitation method. The morphology, structure, electrochemical performance and thermal stability were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, cyclic voltammetry（CV）, electrochemical impedance spectroscopy（EIS）, charge/discharge cycling and differential scanning calorimeter （DSC）. SEM analysis shows that Mg3（PO4）2-coating changes the morphologies of their particles and increases the grains size. XRD and CV results show that Mg3（PO4）2-coating powder is homogeneous and has better layered structure than the bare one. Mg3（PO4）2-coating improved high rate discharge capacity and cycle-life performance. The reason why the cycling performance of Mg3（PO4）2-coated sample at 55 ℃ was better than that of room temperature was the increasing of lithium-ion diffusion rate and charge transfer rate with temperature rising. Mg3（PO4）2-coating improved the cathode thermal stability, and the result was consistent with thermal abuse tests using Li-ion cells： the Mg3（PO4）2 coated Li1.05Ni1/3Mn1/3Co1/3O2 cathode did not exhibit thermal runaway with smoke and explosion, in contrast to the cells containing the bare Li1.05Ni1/3Mn1/3Co1/3O2.
基金Funded by the National Science Foundation of China (No. 50062001)
文摘The cathode materials LiNixCo1-xO2 (0≤x≤1) for lithium ion battery were prepared in solid phase . The effects of synthesis temperature , the time of heat treatment and also the ratio of raw materials on products were discussed . The residts showed that the products preheated under 600℃ and then sintered under constant, temperature 75017 were better than those sintered under constant temperature 650℃ or 850℃ , and their layer structures were more obvious and their initial capacity was higher . The longer the heat-treating time is , the stronger the products ’ XRD peaks intensity and the better their structures and electrochemical performance are. The samples LiN-ix Co 1-xO2(0≤x≤1) with a perfect structure and electrochemical performance were synthesized. And the products initial capacity was perfect when n(Li) : n( Ni) : n( Co) ℃ 1.15:0.3:0.7,viz. 156.l46mAh/g.
文摘A layered oxide Li[Ni1/3Mn1/3Co1/3]O2 was synthesized by an oxalate co- precipitation method. The morphology, structural and composition of the as-papered samples synthesized at different calcination temperatures were investigated. The results indicate that calcination temperature of the sample at 850℃ can improve the integrity of structural significantly. The effect of calcination temperature varying from 750℃ to 950℃ on the electrochemical performance of Li[Ni1/3Mn1/3Co1/3]O2, cathode material of lithiumion batteries, has been investigated. The results show that Li[Ni1/3Mn1/3Co1/3]O2 calcined at 850℃ possesses a higher capacity retention and better rate capability than other samples. The reversible capacity is up to 178.6 mA.h.g-1, and the discharge capacity still remains 176.3 mA-h.g-1 after 30 cycles. Moreover, our strategy provides a simple and highly versatile route in fabricating cathode materials for lithium-ion batteries.
基金supported by the National Natural Science Foun-dation of China, the 111 Project (grant no.: B07004) the Natural Science Foundation for Young Teachers of Beijing University of Chemical Technology (grant no.: QN0723)
文摘Cathode materials Li[CoxNiyMn1-x-y]O2 for lithium secondary batteries have been prepared by a new route using layered double hydroxides （LDHs） as a precursor. The resulting layered phase with the α- NaFe02 structure crystallizes in the rhombohedral system, with space group R-3m having an interlayer spacing close to 0.47 nm. X-ray photoelectron spectroscopy （XPS） was used to measure the oxidation states of Co, Ni and Mn. The effects of varying the Co[Ni[Mn ratio on both the structure and electrochemical properties of Li[CoxNiyMn1-x-y]O2 have been investigated by X-ray diffraction and electrochemical tests. The products demonstrated a rather stable cycling behavior, with a reversible capacity of 118 mAh/g for the layered material with Co/Ni/Mn = 1/1/1.
文摘研究应用于锂二次电池阴极的新型高能量密度存贮材料 L i( Alx Co1- x) O2 的充放电特性 ,并与相同条件下制备的传统材料 L i Co O2 进行对比 .结果表明 ,70 0℃烧结的Li( Al0 .3 Co0 .7) O2 有较好的充放电平台 ,电化学容量大于同样条件下制备的 Li Co O2 .
文摘Porous structure Li[Ni1/3Co1/3Mn1/3]O2 has been synthesized via a facile carbonate co-precipitation method using Li2CO3 as template and lithium-source. The physical and electrochemical properties of the materials were examined by many characterizations including TGA, XRD, SEM, EDS, TEM, BET, CV, EIS and galvanostatic charge-discharge cycling. The results indicate that the as-synthesized materials by this novel method own a well-ordered layered structure a-NaFeO2 [space group： R-3m（166）], porous morphology, and an average primary particle size of about 150 nm. The porous material exhibits larger specific surface area and delivers a high initial capacity of 169.9 mAh·g^-1 at 0.1 C （1 C=180 mA·g ^-1） between 2.7 and 4.3 V, and 126.4, 115.7 mAh.g 1 are still respectively reached at high rate of 10 C and 20 C. After 100 charge-discharge cycles at 1 C, the capacity retention is 93.3%, indicating the excellent cycling stability.
