The recycling of cathode materials from spent lithium-ion battery has attracted extensive attention,but few research have focused on spent blended cathode materials.In reality,the blended materials of lithium iron pho...The recycling of cathode materials from spent lithium-ion battery has attracted extensive attention,but few research have focused on spent blended cathode materials.In reality,the blended materials of lithium iron phosphate and ternary are widely used in electric vehicles,so it is critical to design an effective recycling technique.In this study,an efficient method for recovering Li and Fe from the blended cathode materials of spent LiFePO_(4)and LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)batteries is proposed.First,87%A1 was removed by alkali leaching.Then,91.65%Li,72.08%Ni,64.6%Co and 71.66%Mn were further separated by selective leaching with H_(2)SO_(4)and H_(2)O_(2).Li,Ni,Co and Mn in solution were recovered in the form of Li_(2)CO_(3)and hydroxide respectively.Subsequently,98.38%Fe was leached from the residue by two stage process,and it is recovered as FePO_(4)·2H_(2)O with a purity of 99.5%by precipitation.Fe and P were present in FePO_(4)·2H_(2)O in amounts of 28.34%and 15.98%,respectively.Additionally,the drift and control of various components were discussed,and cost-benefit analysis was used to assess the feasibility of potential application.展开更多
In order to improve the electrochemical performance of polyoxomolybdate Na3[AlMo6O24H6](NAM) as the cathode material of lithium ion battery, the NAM materials with small particle size were synthesized by elevatingth...In order to improve the electrochemical performance of polyoxomolybdate Na3[AlMo6O24H6](NAM) as the cathode material of lithium ion battery, the NAM materials with small particle size were synthesized by elevatingthe synthesistemperaturein the solution.The as-prepared NAM materials were investigated by FT-IR, XRD, SEM and EIS. Their discharge-charge and cycle performance were also tested. The resultsshowthat the particle size decreasesto less than10μm at the temperature ofhigher than 40℃.When synthesized at 80℃,the NAMwiththe smallest particle size (-3μm)exhibitsthe best electrochemical performance such ashigh initial discharge capacity of 409 mA·h/gandcoulombic efficiency of 95% in the first cycle at 0.04C.展开更多
Lithium battery has recently gained more and more attention worldwide.It has wide usage that range from toys to electric cars.Choosing a suitable material that best fits the overall performance as electrode for the ba...Lithium battery has recently gained more and more attention worldwide.It has wide usage that range from toys to electric cars.Choosing a suitable material that best fits the overall performance as electrode for the battery is very essential.For cathode material,apart from the traditional and widely-used LiCoCO_(2),LiFePO_(4)and so on,there are innovations that include the use of V_(2)O_(5).Researches have been done focusing on how to further improve the performance for V_(2)O_(5)cathode in terms of different structure,forms or combination with other chemical molecules.This research paper will make a summary of the materials derived from traditional V_(2)O_(5)as well as their performances.展开更多
LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction(...LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).The charge-discharge test showed that the cycling and rate capacities of LiMn2O4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.展开更多
The polyoxovanadate(NH4)7[MnV13O38](AMV) was synthesized and characterized by X-ray diffraction pattern, Fourier transform infrared spectra, and field emission scanning electron microscope equipped with energy dis...The polyoxovanadate(NH4)7[MnV13O38](AMV) was synthesized and characterized by X-ray diffraction pattern, Fourier transform infrared spectra, and field emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy. In order to improve the electrochemical performance of AMV, the particle size of as-prepared AMV is decreased to nanoscale by re-precipitation in the water-ethanol solution. The results of the electrochemical impedance spectra and the 4-pin probe measurements show that the electrical conductivity of AMV is improved by decreasing the particle size. The nanoparticle AMV shows higher initial discharge capacity and energy density than the as-prepared AMV when cycled at 0.5C. On the other hand, the nanoparticle AMV exhibits higher rate capability than the as-prepared AMV.展开更多
Assisted by graphene oxide(GO),nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indica...Assisted by graphene oxide(GO),nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn0.6Fe0.4PO4(S2)was about 80 nm in diameter.The discharge capacity of LiMn0.6Fe0.4PO4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn0.6Fe0.4PO4 and it in situ reduction of GO could improve the electrical conductivity of LiMn0.6Fe0.4PO4 material.展开更多
Based on synthesizing pure spinel type lithium manganese oxides,the derivations such as LiMn1.5Ti0.5-O4,LiMn1.5Fe0.5O4,LiMn1 .5Ni0.5O4 and LiMn1.5Zn0.5O4 were prepared using solid- step-sintering method. The structure...Based on synthesizing pure spinel type lithium manganese oxides,the derivations such as LiMn1.5Ti0.5-O4,LiMn1.5Fe0.5O4,LiMn1 .5Ni0.5O4 and LiMn1.5Zn0.5O4 were prepared using solid- step-sintering method. The structures were characterized by using XRD,SEM and laser granulometer. The electrochemical measurement results show that the elemen t of iron or nickel can raise the discharging plateau voltage of LiMn2O4,an d element titanium improves the electrochemistry property of LiMn2O4 little,while element zinc destroys the electrochemistry property of LiMn2O4. The i nfluence of elements of titanium,iron,nickel,or zinc on the structure of LiMn 2O4 pure phase was discussed from the viewpoint of structural chemistry.展开更多
The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The...The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The optimum technological condition was obtained through orthogonal experiments by L_9(3~4) and DTA analysis. The result indicates that the factors of effecting the electrochemical properties of synthesized LiNi_(0.8)Co_(0.2)O_2 are molar ratio of Li/Ni/Co, oxygen pressure, homothermal time, the final sintering temperature in turn according to its importance. The oxygen pressure is reviewed independently and the technological condition is further optimized. With the same method, rare earth element Ce was studied as substitute element of Co and the cathode material of LiNi_(0.95)Ce_(0.05)O_2 with excellent electrochemical properties was prepared. The electrochemical testing results of LiNi_(0.8)Co_(0.2)O_2 and LiNi_(0.95)Ce_(0.05)O_2 experimental batteries show that discharge capacities of them reach 165 and 148 mAh·g^(-1) respectively and the persistence is more than 9 h at 3.7 V.展开更多
A new lithium ion battery cathode material, composite oxide LiNi y Co z Mn 1- y-z O 2, was synthesized. The structure and physical properties of the material, including composition, distribution of size, density and s...A new lithium ion battery cathode material, composite oxide LiNi y Co z Mn 1- y-z O 2, was synthesized. The structure and physical properties of the material, including composition, distribution of size, density and specific surface area, were discussed. The characteristic of charge and discharge, reversible specific capacity and cycle property were also studied. The relationship between the structure and properties of the composite oxides was explored. The results show that the composite oxide with a reasonable composition is beneficial to the improvement and enhancement of the properties.展开更多
Li3V2-2/3xMnx(PO4)3(0≤x≤0.12) powders were synthesized by sol-gel method. The effect of Mn2+-doping on the structure and electrochemical performances of Li3V2(PO4)3/C was characterized by XRD, SEM, XPS, galva...Li3V2-2/3xMnx(PO4)3(0≤x≤0.12) powders were synthesized by sol-gel method. The effect of Mn2+-doping on the structure and electrochemical performances of Li3V2(PO4)3/C was characterized by XRD, SEM, XPS, galvanostatic charge /discharge and electrochemical impedance spectroscopy(EIS). The XRD study shows that a small amount of Mn2+-doped does not alter the structure of Li3V2(PO4)3/C materials, and all Mn2+-doped samples are of pure single phase with a monoclinic structure (space group P21/n). The XPS analysis indicates that valences state of V and Mn are +3 and +2 in Li3V1.94Mn0.09(PO4)3/C, respectively, and the citric acid in raw materials was decomposed into carbon during calcination, and residual carbon exists in Li3V1.94Mn0.09(PO4)/C. The results of electrochemical measurements show that Mn2+-doping can improve the cyclic stability and rate performance of these cathode materials. The Li3V1.94Mn0.09(PO4)3/C cathode material shows the best cyclic stability and rate performance. For example, at the discharge current density of 40 mA/g, after 100 cycles, the discharge capacity of Li3V1.94Mn0.09(PO4)3/C declines from initial 158.8 mA·h/g to 120.5 mA·h/g with a capacity retention of 75.9%; however, that of the Mn-undoed sample declines from 164.2 mA·h/g to 72.6 mA·h/g with a capacity retention of 44.2%. When the discharge current is increased up to 1C, the intial discharge capacity of Li3V1.94Mn0.09(PO4)3/C still reaches 146.4 mA·h/g, and the discharge capacity maintains at 107.5 mA·h/g after 100 cycles. The EIS measurement indicates that Mn2+-doping with a appropriate amount of Mn2+ decreases the charge transfer resistance, which is favorable for the insertion/extraction of Li+.展开更多
Li3Mg(2x)V(2-2x)(PO4)3/C(x=0,0.05,0.1,0.2) composites were synthesized by carbothermic reduction,using a self-made MgNH4PO4/MgHPO4 compound as Mg-doping agent.X-ray diffraction(XRD),scanning electron microsc...Li3Mg(2x)V(2-2x)(PO4)3/C(x=0,0.05,0.1,0.2) composites were synthesized by carbothermic reduction,using a self-made MgNH4PO4/MgHPO4 compound as Mg-doping agent.X-ray diffraction(XRD),scanning electron microscope(SEM),electrochemical performance tests were employed to investigate the effect of Mg doping on Li3V2(PO4)3/C samples.The results showed that a proper quantity of Mg doping was beneficial to the reduction of charge transfer resistance of Li3V2(PO4)3/C compound without changing the lattice structure,which led to larger charge/discharge capacity and better cycle performance especially at high current density.Li3Mg(2x)V(2-2x)(PO4)3/C sample with x=0.05 exhibited a better performance with initial charge/discharge capacity of146/128 mA·h/g and discharge capacity of 115 mA·h/g at 5C,while these two figures were 142/118 mA·h/g and 90 mA·h/g respectively for samples without Mg doping,indicating that a proper amount of doped Mg can improve the electrochemical performance of LVP sample.All of these proved that,as a trial Mg dopant,the synthesized MgNH4PO4/MgHPO4 compound exhibited well doping effect.展开更多
Y-doped Li3V2(PO4)3 cathode materials were prepared by a carbothermal reduction(CTR) process.The properties of the Y-doped Li3V2(PO4)3 were investigated by X-ray diffraction(XRD) and electrochemical measuremen...Y-doped Li3V2(PO4)3 cathode materials were prepared by a carbothermal reduction(CTR) process.The properties of the Y-doped Li3V2(PO4)3 were investigated by X-ray diffraction(XRD) and electrochemical measurements.XRD studies showed that the Y-doped Li3V2(PO4)3 had the same monoclinic structure as the undoped Li3V2(PO4)3.The Y-doped Li3V2(PO4)3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram(CV), and electrochemical impedance spectra(EIS).The optimal doping content of Y was x=0.03 in Li3V2-xYx(PO4)3 system.The Y-doped Li3V2(PO4)3 samples showed a better cyclic ability.The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Y-doping.The improved electrochemical perormances of the Y-doped Li3V2(PO4)3 cathode materials were attributed to the addition of Y3+ ion by stabilizing the monoclinic structure.展开更多
Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01~0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of t...Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01~0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of the LiCo 1- x RE x O 2 were investigated by XRD. It was found that the lattice parameters c are increased and the lattice volumes are enlarged compared to that of LiCoO 2. Moreover, the performance of LiCo 1- x RE x O 2 as the cathode material in lithium ion battery is improved, especially LiCo 1- x Y x O 2 and LiCo 1- x La x O 2. The initial charge/discharge capacities of LiCo 0.99 Y 0.01 O 2 and LiCo 0.99 La 0.01 O 2 are 174/154 (mAh·g -1 ) and 159/149 (mAh·g -1 ) respectively, while those for LiCoO 2 working in the same way are only 139/131 (mAh·g -1 ).展开更多
A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction (CTR) process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted un...A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction (CTR) process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3+ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure(space group p I ), isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V (vs Ei/Li^+), and the capacity retains 89 mA·h/g after 30 cycles.展开更多
La-doped Li3V2-xLax(PO4)3 ( x = 0.01, 0.02, and 0.03) cathode materials for lithium ion batteries were synthesized by the microwave-assisted carbothermal reduction method (MW-CTR). The structures and properties ...La-doped Li3V2-xLax(PO4)3 ( x = 0.01, 0.02, and 0.03) cathode materials for lithium ion batteries were synthesized by the microwave-assisted carbothermal reduction method (MW-CTR). The structures and properties of the prepared samples were investigated by X-ray diffraction (XRD) and electrochemical measurements. The results showed that all the three Li3V2-xLax(PO4)3 samples had the same monocfinic structures and sharper diffraction peaks of the crystal plane compared with those of the undoped Li3V2(PO4)3. The initial charge/discharge specific capacity, coulomb efficiency, and discharge decay rate of all the three Li3V2-xLax(PO4)3 samples were superior to those of the undoped Li3V2(PO4)3 sample, and the Li3V1.98La0.02(PO4)3 sample exhibited the best features among the three La-doped Li3V2-xLax(PO4)3 samples. Electrochemical impedance spectroscopy (EIS) demonstrated that the Li3V1.98Lao.02(PO4)3 sample had a lower charge transfer resistance and a higher Li ion diffusion coefficient compared with the undoped Li3V2 (PO4)3 sample.展开更多
Ribbon-like Cu doped V6O(13) was synthesized via a simple solvothermal approach followed by heat treatment in air.As an cathode material for lithium ion battery,the ribbon-like Cu doped V6O(13 )electrode exhibited...Ribbon-like Cu doped V6O(13) was synthesized via a simple solvothermal approach followed by heat treatment in air.As an cathode material for lithium ion battery,the ribbon-like Cu doped V6O(13 )electrode exhibited good capacity retention with a reversible capacity of over 313 m Ah·g^-1 for up to 50 cycles at 0.1C,as well as a high charge capacity of 306 m Ah·g^-1 at a high current rate of 1 C,in comparison to undoped V6O(13 )electrode(267 m Ah·g^-1 at 0.1C and 273 m Ah·g^-1 at 1 C).The high rate capability and better cycleability of the doped electrode can be attributed to the influence of the Cu ions on the mophology and the electronic conductivity of V6O(13) during the lithiation and delithiation process.展开更多
In situ chemical oxidation polymerization of pyrrole on the surface of sulfur particles was carried out to synthesize a sulfur/polypyrrole (SIPPy) nanocomposite with core-shell structure. The composite was character...In situ chemical oxidation polymerization of pyrrole on the surface of sulfur particles was carried out to synthesize a sulfur/polypyrrole (SIPPy) nanocomposite with core-shell structure. The composite was characterized by elemental analysis, X-ray diffraction, scanning/transmission electron microscopy, and electrochemical measurements. XRD and FTIR results showed that sulfur well dispersed in the core-shell structure and PPy structure was successfully obtained via in situ oxidative polymerization of pyrrole on the surface of sulfur particles. TEM observation revealed that PPy was formed and fixed to the surface of sulfur nanoparticle after polymerization, developing a well-defined core-shell structure and the thickness of PPy coating layer was in the range of 20-30 nm. In the composite, PPy worked as a conducting matrix as well as a coating agent, which confined the active materials within the electrode. Consequently, the as prepared SIPPy composite cathode exhibited good cycling and rate performances for rechargeable lithium/sulfur batteries. The resulting cell containing SIPPy composite cathode yields a discharge capacity of 1039 mAh·g^-1 at the initial cycle and retains 59% of this value over 50 cycles at 0.1 C rate. At 1 C rate, the SIPPy composite showed good cycle stability, and the discharge capacity was 475 mAh·g^-1 after 50 cycles.展开更多
The tmiform layered Li(Ni2/8Co3/8Mn3/8)O2, Li(Ni3/8Co2/8Mn3/8)O2, and Li(Ni3/8Co3/8Mn2/8)O2 cathode materials for lithium ion batteries were prepared using the hydroxide co-precipitation method. The effects of c...The tmiform layered Li(Ni2/8Co3/8Mn3/8)O2, Li(Ni3/8Co2/8Mn3/8)O2, and Li(Ni3/8Co3/8Mn2/8)O2 cathode materials for lithium ion batteries were prepared using the hydroxide co-precipitation method. The effects of calcination temperature and transition metal contents on the structure and electrochemical properties of the Li-Ni-Co-Mn-O were systemically studied. The results of XRD and electrochemical performance measurement show that the ideal preparation conditions were to prepare the Li(Ni3/8Co3/8Mn2/8)O2 cathode material calcined at 900℃ for 10 h. The well-ordered Li(Ni3/8Co3/8Mn2/8)O2 synthesized under the optimal conditions has the I003/I104 ratio of 1.25 and the R value of 0.48 and delivers the initial discharge capacity of 172.9 mA·h·g^-1, the discharge capacity of 166.2 mA·h·g^-1 after 20 cycles at 0.2C rate, and the impedance of 558 Ω after the first cycle. The decrease of Ni content results in the decrease of discharge capacity and the bad cycling performance of the Li-Ni-Co-Mn-O cathode materials, but the decreases of Mn content and Co content to a certain extent can improve the electrochemical properties of the Li-Ni-Co-Mn-O cathode materials.展开更多
Some rare earth doping spinel LiMn_(2-x)RE_xO_4 (RE=La, Ce, Nd) cathode materials for lithium ion batteries were synthesized by the solid-state reaction method. The structure characteristics of these produced samples ...Some rare earth doping spinel LiMn_(2-x)RE_xO_4 (RE=La, Ce, Nd) cathode materials for lithium ion batteries were synthesized by the solid-state reaction method. The structure characteristics of these produced samples were investigated by XRD, SEM, and particle size distribution analysis. According to the microstructure and charge-discharge testing, the effect of doping rare earth on stabilizing the spinel structure was analyzed. Through a series of doping experiments, it is shown that when the doping content x within the range of 0.01~0.02 the cycle performance of the materials is greatly improved. The discharge capacity of the sample LiMn_(1.98)La_(0.02)O_4, LiMn_(1.98)Ce_(0.02)O_4 and LiMn_(1.98)Nd_(0.02)O_4 remain 119.1, 114.2 and 117.5 mAh·g^(-1) after 50 cycles.展开更多
基金financially supported by the National Key Research and Development Program(Nos.2019YFC1907801,2019YFC1907803 and 2019YFC1907804)the Natural Science Foundation of Hunan(Nos.2021JJ2020066 and 2020JJ4733)+1 种基金the National Natural Science Foundation of China(No.51904340)the Central South University Innovation-Driven Research Program(No.2023CXQD009)。
文摘The recycling of cathode materials from spent lithium-ion battery has attracted extensive attention,but few research have focused on spent blended cathode materials.In reality,the blended materials of lithium iron phosphate and ternary are widely used in electric vehicles,so it is critical to design an effective recycling technique.In this study,an efficient method for recovering Li and Fe from the blended cathode materials of spent LiFePO_(4)and LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)batteries is proposed.First,87%A1 was removed by alkali leaching.Then,91.65%Li,72.08%Ni,64.6%Co and 71.66%Mn were further separated by selective leaching with H_(2)SO_(4)and H_(2)O_(2).Li,Ni,Co and Mn in solution were recovered in the form of Li_(2)CO_(3)and hydroxide respectively.Subsequently,98.38%Fe was leached from the residue by two stage process,and it is recovered as FePO_(4)·2H_(2)O with a purity of 99.5%by precipitation.Fe and P were present in FePO_(4)·2H_(2)O in amounts of 28.34%and 15.98%,respectively.Additionally,the drift and control of various components were discussed,and cost-benefit analysis was used to assess the feasibility of potential application.
文摘In order to improve the electrochemical performance of polyoxomolybdate Na3[AlMo6O24H6](NAM) as the cathode material of lithium ion battery, the NAM materials with small particle size were synthesized by elevatingthe synthesistemperaturein the solution.The as-prepared NAM materials were investigated by FT-IR, XRD, SEM and EIS. Their discharge-charge and cycle performance were also tested. The resultsshowthat the particle size decreasesto less than10μm at the temperature ofhigher than 40℃.When synthesized at 80℃,the NAMwiththe smallest particle size (-3μm)exhibitsthe best electrochemical performance such ashigh initial discharge capacity of 409 mA·h/gandcoulombic efficiency of 95% in the first cycle at 0.04C.
文摘Lithium battery has recently gained more and more attention worldwide.It has wide usage that range from toys to electric cars.Choosing a suitable material that best fits the overall performance as electrode for the battery is very essential.For cathode material,apart from the traditional and widely-used LiCoCO_(2),LiFePO_(4)and so on,there are innovations that include the use of V_(2)O_(5).Researches have been done focusing on how to further improve the performance for V_(2)O_(5)cathode in terms of different structure,forms or combination with other chemical molecules.This research paper will make a summary of the materials derived from traditional V_(2)O_(5)as well as their performances.
基金financially supported by the National High-Tech Research and Development(863) Program of China(No.2006AA11A160)the National Natural Science Foundation of China(No.50604018)
文摘LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).The charge-discharge test showed that the cycling and rate capacities of LiMn2O4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.
文摘The polyoxovanadate(NH4)7[MnV13O38](AMV) was synthesized and characterized by X-ray diffraction pattern, Fourier transform infrared spectra, and field emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy. In order to improve the electrochemical performance of AMV, the particle size of as-prepared AMV is decreased to nanoscale by re-precipitation in the water-ethanol solution. The results of the electrochemical impedance spectra and the 4-pin probe measurements show that the electrical conductivity of AMV is improved by decreasing the particle size. The nanoparticle AMV shows higher initial discharge capacity and energy density than the as-prepared AMV when cycled at 0.5C. On the other hand, the nanoparticle AMV exhibits higher rate capability than the as-prepared AMV.
基金supported by 973(2011CB935900,2010CB631303)NSFC(21231005,51071087)+4 种基金111 Project(B12015)MOE(IRT13R30)the Research Fund for the Doctoral Program of Higher Education of China(20120031110001)Tianjin Sci&Tech Project(10SYSYJC27600)the Nature Science Foundation of Tianjin(11JCYBJC07700)
文摘Assisted by graphene oxide(GO),nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn0.6Fe0.4PO4(S2)was about 80 nm in diameter.The discharge capacity of LiMn0.6Fe0.4PO4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn0.6Fe0.4PO4 and it in situ reduction of GO could improve the electrical conductivity of LiMn0.6Fe0.4PO4 material.
文摘Based on synthesizing pure spinel type lithium manganese oxides,the derivations such as LiMn1.5Ti0.5-O4,LiMn1.5Fe0.5O4,LiMn1 .5Ni0.5O4 and LiMn1.5Zn0.5O4 were prepared using solid- step-sintering method. The structures were characterized by using XRD,SEM and laser granulometer. The electrochemical measurement results show that the elemen t of iron or nickel can raise the discharging plateau voltage of LiMn2O4,an d element titanium improves the electrochemistry property of LiMn2O4 little,while element zinc destroys the electrochemistry property of LiMn2O4. The i nfluence of elements of titanium,iron,nickel,or zinc on the structure of LiMn 2O4 pure phase was discussed from the viewpoint of structural chemistry.
文摘The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The optimum technological condition was obtained through orthogonal experiments by L_9(3~4) and DTA analysis. The result indicates that the factors of effecting the electrochemical properties of synthesized LiNi_(0.8)Co_(0.2)O_2 are molar ratio of Li/Ni/Co, oxygen pressure, homothermal time, the final sintering temperature in turn according to its importance. The oxygen pressure is reviewed independently and the technological condition is further optimized. With the same method, rare earth element Ce was studied as substitute element of Co and the cathode material of LiNi_(0.95)Ce_(0.05)O_2 with excellent electrochemical properties was prepared. The electrochemical testing results of LiNi_(0.8)Co_(0.2)O_2 and LiNi_(0.95)Ce_(0.05)O_2 experimental batteries show that discharge capacities of them reach 165 and 148 mAh·g^(-1) respectively and the persistence is more than 9 h at 3.7 V.
文摘A new lithium ion battery cathode material, composite oxide LiNi y Co z Mn 1- y-z O 2, was synthesized. The structure and physical properties of the material, including composition, distribution of size, density and specific surface area, were discussed. The characteristic of charge and discharge, reversible specific capacity and cycle property were also studied. The relationship between the structure and properties of the composite oxides was explored. The results show that the composite oxide with a reasonable composition is beneficial to the improvement and enhancement of the properties.
基金Project (20771100) supported by the National Natural Science Foundation of China
文摘Li3V2-2/3xMnx(PO4)3(0≤x≤0.12) powders were synthesized by sol-gel method. The effect of Mn2+-doping on the structure and electrochemical performances of Li3V2(PO4)3/C was characterized by XRD, SEM, XPS, galvanostatic charge /discharge and electrochemical impedance spectroscopy(EIS). The XRD study shows that a small amount of Mn2+-doped does not alter the structure of Li3V2(PO4)3/C materials, and all Mn2+-doped samples are of pure single phase with a monoclinic structure (space group P21/n). The XPS analysis indicates that valences state of V and Mn are +3 and +2 in Li3V1.94Mn0.09(PO4)3/C, respectively, and the citric acid in raw materials was decomposed into carbon during calcination, and residual carbon exists in Li3V1.94Mn0.09(PO4)/C. The results of electrochemical measurements show that Mn2+-doping can improve the cyclic stability and rate performance of these cathode materials. The Li3V1.94Mn0.09(PO4)3/C cathode material shows the best cyclic stability and rate performance. For example, at the discharge current density of 40 mA/g, after 100 cycles, the discharge capacity of Li3V1.94Mn0.09(PO4)3/C declines from initial 158.8 mA·h/g to 120.5 mA·h/g with a capacity retention of 75.9%; however, that of the Mn-undoed sample declines from 164.2 mA·h/g to 72.6 mA·h/g with a capacity retention of 44.2%. When the discharge current is increased up to 1C, the intial discharge capacity of Li3V1.94Mn0.09(PO4)3/C still reaches 146.4 mA·h/g, and the discharge capacity maintains at 107.5 mA·h/g after 100 cycles. The EIS measurement indicates that Mn2+-doping with a appropriate amount of Mn2+ decreases the charge transfer resistance, which is favorable for the insertion/extraction of Li+.
基金Project(2014CB643405)supported by the National Basic Research Program of China
文摘Li3Mg(2x)V(2-2x)(PO4)3/C(x=0,0.05,0.1,0.2) composites were synthesized by carbothermic reduction,using a self-made MgNH4PO4/MgHPO4 compound as Mg-doping agent.X-ray diffraction(XRD),scanning electron microscope(SEM),electrochemical performance tests were employed to investigate the effect of Mg doping on Li3V2(PO4)3/C samples.The results showed that a proper quantity of Mg doping was beneficial to the reduction of charge transfer resistance of Li3V2(PO4)3/C compound without changing the lattice structure,which led to larger charge/discharge capacity and better cycle performance especially at high current density.Li3Mg(2x)V(2-2x)(PO4)3/C sample with x=0.05 exhibited a better performance with initial charge/discharge capacity of146/128 mA·h/g and discharge capacity of 115 mA·h/g at 5C,while these two figures were 142/118 mA·h/g and 90 mA·h/g respectively for samples without Mg doping,indicating that a proper amount of doped Mg can improve the electrochemical performance of LVP sample.All of these proved that,as a trial Mg dopant,the synthesized MgNH4PO4/MgHPO4 compound exhibited well doping effect.
基金supported by Guangxi Natural Science Foundation (0832259)Program to Sponsor Teams for Innovation in the Construction of Talent Highlands in Guangxi Institutions of Higher Learning (GuiJiaoRen [2007]71)Research Funds of the Guangxi Key Laboratory of Environmental Engineering, Protection and Assessment
文摘Y-doped Li3V2(PO4)3 cathode materials were prepared by a carbothermal reduction(CTR) process.The properties of the Y-doped Li3V2(PO4)3 were investigated by X-ray diffraction(XRD) and electrochemical measurements.XRD studies showed that the Y-doped Li3V2(PO4)3 had the same monoclinic structure as the undoped Li3V2(PO4)3.The Y-doped Li3V2(PO4)3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram(CV), and electrochemical impedance spectra(EIS).The optimal doping content of Y was x=0.03 in Li3V2-xYx(PO4)3 system.The Y-doped Li3V2(PO4)3 samples showed a better cyclic ability.The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Y-doping.The improved electrochemical perormances of the Y-doped Li3V2(PO4)3 cathode materials were attributed to the addition of Y3+ ion by stabilizing the monoclinic structure.
文摘Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01~0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of the LiCo 1- x RE x O 2 were investigated by XRD. It was found that the lattice parameters c are increased and the lattice volumes are enlarged compared to that of LiCoO 2. Moreover, the performance of LiCo 1- x RE x O 2 as the cathode material in lithium ion battery is improved, especially LiCo 1- x Y x O 2 and LiCo 1- x La x O 2. The initial charge/discharge capacities of LiCo 0.99 Y 0.01 O 2 and LiCo 0.99 La 0.01 O 2 are 174/154 (mAh·g -1 ) and 159/149 (mAh·g -1 ) respectively, while those for LiCoO 2 working in the same way are only 139/131 (mAh·g -1 ).
基金financially supported by NSAF(No.U1530155)Ministry of Science and Technology(MOST)of China,US–China Collaboration on Cutting-edge Technology Development of Electric Vehicle,the Nation Key Basic Research Program of China(No.2015CB251100)Beijing Key Laboratory of Environmental Science and Engineering(No.20131039031)
基金Project(50302016) supported by the National Natural Science Foundation of China
文摘A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction (CTR) process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3+ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure(space group p I ), isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V (vs Ei/Li^+), and the capacity retains 89 mA·h/g after 30 cycles.
基金supported by the Key Research Project of the Science and Technology Department of Jiangxi Province,China (2006)
文摘La-doped Li3V2-xLax(PO4)3 ( x = 0.01, 0.02, and 0.03) cathode materials for lithium ion batteries were synthesized by the microwave-assisted carbothermal reduction method (MW-CTR). The structures and properties of the prepared samples were investigated by X-ray diffraction (XRD) and electrochemical measurements. The results showed that all the three Li3V2-xLax(PO4)3 samples had the same monocfinic structures and sharper diffraction peaks of the crystal plane compared with those of the undoped Li3V2(PO4)3. The initial charge/discharge specific capacity, coulomb efficiency, and discharge decay rate of all the three Li3V2-xLax(PO4)3 samples were superior to those of the undoped Li3V2(PO4)3 sample, and the Li3V1.98La0.02(PO4)3 sample exhibited the best features among the three La-doped Li3V2-xLax(PO4)3 samples. Electrochemical impedance spectroscopy (EIS) demonstrated that the Li3V1.98Lao.02(PO4)3 sample had a lower charge transfer resistance and a higher Li ion diffusion coefficient compared with the undoped Li3V2 (PO4)3 sample.
基金Funded by the Program for New Century Excellent Talents in University of Ministry of Education,(No.NCET-12-0655)the Guangxi Natural Science Foundation(No.2014GXNSFFA118004)
文摘Ribbon-like Cu doped V6O(13) was synthesized via a simple solvothermal approach followed by heat treatment in air.As an cathode material for lithium ion battery,the ribbon-like Cu doped V6O(13 )electrode exhibited good capacity retention with a reversible capacity of over 313 m Ah·g^-1 for up to 50 cycles at 0.1C,as well as a high charge capacity of 306 m Ah·g^-1 at a high current rate of 1 C,in comparison to undoped V6O(13 )electrode(267 m Ah·g^-1 at 0.1C and 273 m Ah·g^-1 at 1 C).The high rate capability and better cycleability of the doped electrode can be attributed to the influence of the Cu ions on the mophology and the electronic conductivity of V6O(13) during the lithiation and delithiation process.
基金supported by the Natural Science Foundation of Shaanxi Province,China(2013JM2009)
文摘In situ chemical oxidation polymerization of pyrrole on the surface of sulfur particles was carried out to synthesize a sulfur/polypyrrole (SIPPy) nanocomposite with core-shell structure. The composite was characterized by elemental analysis, X-ray diffraction, scanning/transmission electron microscopy, and electrochemical measurements. XRD and FTIR results showed that sulfur well dispersed in the core-shell structure and PPy structure was successfully obtained via in situ oxidative polymerization of pyrrole on the surface of sulfur particles. TEM observation revealed that PPy was formed and fixed to the surface of sulfur nanoparticle after polymerization, developing a well-defined core-shell structure and the thickness of PPy coating layer was in the range of 20-30 nm. In the composite, PPy worked as a conducting matrix as well as a coating agent, which confined the active materials within the electrode. Consequently, the as prepared SIPPy composite cathode exhibited good cycling and rate performances for rechargeable lithium/sulfur batteries. The resulting cell containing SIPPy composite cathode yields a discharge capacity of 1039 mAh·g^-1 at the initial cycle and retains 59% of this value over 50 cycles at 0.1 C rate. At 1 C rate, the SIPPy composite showed good cycle stability, and the discharge capacity was 475 mAh·g^-1 after 50 cycles.
基金supported by the Natural Science Foundation of Hunan Province, China (No. 07JJ6082)
文摘The tmiform layered Li(Ni2/8Co3/8Mn3/8)O2, Li(Ni3/8Co2/8Mn3/8)O2, and Li(Ni3/8Co3/8Mn2/8)O2 cathode materials for lithium ion batteries were prepared using the hydroxide co-precipitation method. The effects of calcination temperature and transition metal contents on the structure and electrochemical properties of the Li-Ni-Co-Mn-O were systemically studied. The results of XRD and electrochemical performance measurement show that the ideal preparation conditions were to prepare the Li(Ni3/8Co3/8Mn2/8)O2 cathode material calcined at 900℃ for 10 h. The well-ordered Li(Ni3/8Co3/8Mn2/8)O2 synthesized under the optimal conditions has the I003/I104 ratio of 1.25 and the R value of 0.48 and delivers the initial discharge capacity of 172.9 mA·h·g^-1, the discharge capacity of 166.2 mA·h·g^-1 after 20 cycles at 0.2C rate, and the impedance of 558 Ω after the first cycle. The decrease of Ni content results in the decrease of discharge capacity and the bad cycling performance of the Li-Ni-Co-Mn-O cathode materials, but the decreases of Mn content and Co content to a certain extent can improve the electrochemical properties of the Li-Ni-Co-Mn-O cathode materials.
基金Project supported by the National Natural Science Foundation of China (20273047)
文摘Some rare earth doping spinel LiMn_(2-x)RE_xO_4 (RE=La, Ce, Nd) cathode materials for lithium ion batteries were synthesized by the solid-state reaction method. The structure characteristics of these produced samples were investigated by XRD, SEM, and particle size distribution analysis. According to the microstructure and charge-discharge testing, the effect of doping rare earth on stabilizing the spinel structure was analyzed. Through a series of doping experiments, it is shown that when the doping content x within the range of 0.01~0.02 the cycle performance of the materials is greatly improved. The discharge capacity of the sample LiMn_(1.98)La_(0.02)O_4, LiMn_(1.98)Ce_(0.02)O_4 and LiMn_(1.98)Nd_(0.02)O_4 remain 119.1, 114.2 and 117.5 mAh·g^(-1) after 50 cycles.