To achieve large-scale application of solvothermal method and settle structural collapse of polycrystalline ternary NCM cathode materials(LiNi0.8Co0.1Mn0.1O2,NCM811)during long charge and discharge cycling,single-crys...To achieve large-scale application of solvothermal method and settle structural collapse of polycrystalline ternary NCM cathode materials(LiNi0.8Co0.1Mn0.1O2,NCM811)during long charge and discharge cycling,single-crystalline NCM materials with high cycling stability were prepared by rapid ethanol-water solvothermal method.The morphology and electrochemical properties of NCM materials were characterized by X-ray diffractometry,cross-section scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy,and electrochemical measurement.The results show that single-crystalline NCM synthesized with 60 min solvothermal time has the most excellent electrochemical performance.Its reversible capacity reaches 157.28 mA·h/g at 1C and retention rate achieves 55.06%after 200 cycles,which is much better than the polycrystalline NCM cathode material.Cross-section scanning electron microscopy results show that the single-crystalline NCM cathode material has no apparent cracks after 200 cycles.展开更多
Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acet...Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acetylene black composite and MWNTs in 1.0 mol·L-1 LiClO4 / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi0.8Co0.2O2 / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g-1, while the energy density is up to 339.5 Wh·kg-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.展开更多
LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-preci...LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.展开更多
The microwave coprecipitation method was used to synthesize α-Ni0.8Co0.2(OH)2 precursor for preparing LiNi0.8Co0.2O2 cathode material.The precursor α-Ni0.8Co0.2(OH)2 was mixed with LiOH·H2O and then calcined in...The microwave coprecipitation method was used to synthesize α-Ni0.8Co0.2(OH)2 precursor for preparing LiNi0.8Co0.2O2 cathode material.The precursor α-Ni0.8Co0.2(OH)2 was mixed with LiOH·H2O and then calcined in O2 for 10 h at different temperatures(700℃,800℃,900℃).XRD,SEM analyses and electrochemical tests were used to study the physical and electrochemical performance of the cathode material.With increasing calcination temperature,the characteristic peaks of the cathode materials became stronger and sharper,corresponding to a perfect crystalization.The results of electrochemical tests indicate that the sample LiNi0.8Co0.2O2 (900℃)showed excellent electrochemical properties,with an initial discharge capacity of 189.1 mA·h·g-1 and an initial discharge efficiency of 92.5%.After 30 cycles,the discharge capacity was still 148 mA·h·g-1,showing good cyclic stability.展开更多
The gradient composite LiNi0.8Co0.2O2 was synthesized using spherical Ni(OH)2 particle coated by a sol-gel containing cobalt and lithium. The precursor was examined by DSC-TG. The gradient composite was characterized ...The gradient composite LiNi0.8Co0.2O2 was synthesized using spherical Ni(OH)2 particle coated by a sol-gel containing cobalt and lithium. The precursor was examined by DSC-TG. The gradient composite was characterized by SEM, EDS, XPS, XRD and ICP-AES. The XPS, EDS and ICP-AES results show that content of cobalt in the surface is higher than in the center of the spherical particle of the gradient composite. The first discharge specific capacity of the gradient composite sintered at 700 ℃ is 187.3 mAh·g-1.展开更多
With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical pe...With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical performances of LiNi0.8Co0.2O2 particles were studied in a voltage window of 3.00-4.35 V and at a current density of 30 mA/g. The results show that in the pilot-scale spray pyrolysis process, the morphology of particles is dependent upon the precursor concentration and flux of carrier gas. The initial discharge capacity of the LiNi0.8Co0.2O2particles at 720 ℃ for 12 h is 187.3 mA.h/g, and the capacity remains 96.8% with excellent cycleability after 30 cycles. The LiNi0.8Co0.2O2 samples synthesized under the optimized conditions by the spray pyrolysis method shows a good electrochemical performance.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22068009,22262006)the Science and Technology Support Project of Guizhou Provincial Science and Technology Department,China(Nos.ZK[2023]050 and ZK[2023]403)Guizhou Province Outstanding Young Scientific and Technological Talents Program,China(No.YQK2023007)。
摘要To achieve large-scale application of solvothermal method and settle structural collapse of polycrystalline ternary NCM cathode materials(LiNi0.8Co0.1Mn0.1O2,NCM811)during long charge and discharge cycling,single-crystalline NCM materials with high cycling stability were prepared by rapid ethanol-water solvothermal method.The morphology and electrochemical properties of NCM materials were characterized by X-ray diffractometry,cross-section scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy,and electrochemical measurement.The results show that single-crystalline NCM synthesized with 60 min solvothermal time has the most excellent electrochemical performance.Its reversible capacity reaches 157.28 mA·h/g at 1C and retention rate achieves 55.06%after 200 cycles,which is much better than the polycrystalline NCM cathode material.Cross-section scanning electron microscopy results show that the single-crystalline NCM cathode material has no apparent cracks after 200 cycles.
摘要Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2 / MWNTs composite and LiNi0.8Co0.2O2/acetylene black composite and MWNTs in 1.0 mol·L-1 LiClO4 / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi0.8Co0.2O2 / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g-1, while the energy density is up to 339.5 Wh·kg-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.
摘要LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.
摘要The microwave coprecipitation method was used to synthesize α-Ni0.8Co0.2(OH)2 precursor for preparing LiNi0.8Co0.2O2 cathode material.The precursor α-Ni0.8Co0.2(OH)2 was mixed with LiOH·H2O and then calcined in O2 for 10 h at different temperatures(700℃,800℃,900℃).XRD,SEM analyses and electrochemical tests were used to study the physical and electrochemical performance of the cathode material.With increasing calcination temperature,the characteristic peaks of the cathode materials became stronger and sharper,corresponding to a perfect crystalization.The results of electrochemical tests indicate that the sample LiNi0.8Co0.2O2 (900℃)showed excellent electrochemical properties,with an initial discharge capacity of 189.1 mA·h·g-1 and an initial discharge efficiency of 92.5%.After 30 cycles,the discharge capacity was still 148 mA·h·g-1,showing good cyclic stability.
摘要The gradient composite LiNi0.8Co0.2O2 was synthesized using spherical Ni(OH)2 particle coated by a sol-gel containing cobalt and lithium. The precursor was examined by DSC-TG. The gradient composite was characterized by SEM, EDS, XPS, XRD and ICP-AES. The XPS, EDS and ICP-AES results show that content of cobalt in the surface is higher than in the center of the spherical particle of the gradient composite. The first discharge specific capacity of the gradient composite sintered at 700 ℃ is 187.3 mAh·g-1.
基金Project(50604018) supported by the National Natural Science Foundation of China
摘要With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical performances of LiNi0.8Co0.2O2 particles were studied in a voltage window of 3.00-4.35 V and at a current density of 30 mA/g. The results show that in the pilot-scale spray pyrolysis process, the morphology of particles is dependent upon the precursor concentration and flux of carrier gas. The initial discharge capacity of the LiNi0.8Co0.2O2particles at 720 ℃ for 12 h is 187.3 mA.h/g, and the capacity remains 96.8% with excellent cycleability after 30 cycles. The LiNi0.8Co0.2O2 samples synthesized under the optimized conditions by the spray pyrolysis method shows a good electrochemical performance.