| LiNi0.5Mn1.5O4 as high-voltage cathode material for lithium ion batteries could reversibly intercalate/deintercalate lithium ions at 4.7V plateaus and with 146.7mAh/g as its theoretical capacity. due to its high operating voltage and energy density, it is possible to meet the large demand for power equipment,and has a very broad development prospects.In this paper, spinel cathode material Li Ni0.5Mn1.5O4 was successfully prepared through solid-phase method, sol-gel method and organic co-precipitation method,The materials were characterized using XRD, SEM and constant current charge and discharge, etc.Characterization results, the material is prepared with cubic spinel structure, the high temperature sintering process will occur NiO and LiyNi1-yO impurities, FTIR test results: the space structure of the prepared material is between ordered and disordered.SEM test results:the material produced are cubic structure, the particle size is relatively uniform, but different methods will result in relatively particle sizes.Solid-phase method studied the effect of tempering and hardening of the material properties.FTIR test results show the order of the materials was increased, electrochemical properties of the material is relatively good. Further research was focused on the tempering time influence, tested results shows that with temperature time increasine, ordered material can be go,the optimal temperature time was 48 h.the materials show high discharge capacity,rate cycle stability.Firstly,Sol-gel method studied the effect of different ligands on material properties,performance tested shows that the combination of citric acid and ethylene glycol as a ligand was the best choose. Secondly, when using template-assisted methods, templati ng agent were used sodium dodecylbenzene sulfonate, polyvinylpyrrolidone and sodium carboxymethylcellulose, the best concentration of sodium dodecylbenzenesulfonate is 0.04 mol / L, the best mass ratio of polyvinylpyrrolidone was 4%, the best concentrati on of sodium carboxymethylcellulose is 0.04mol/L.Firstly, compared inorganic co-precipitation, solid phase and an organic co-precipitation method, result showed: the materials with uniformly fine particle size, excell ent specific capacity, high rate capability and good cycle stability was synthesised by co-precipitation method. Secondly, study the effects of different high-temperature calci nation time on the material properties.Thirdly, Li Ni0.5Mn1.5O4 was synthesised by agent-assisted co-precipitation method,physical properties and electrochemical characterization wse studied also.XRD patterns show that prepared material belong cubic spinel struct ure,FTIR patterns show that the spatial structure of prepared material is between order and disorder.when the high-temperature calcination is12 h,the material has high dischar ge capacity. the best mass ratio of polyvinylpyrrolidone was 4%,the best concentration of sodium dodecylbenzenesulfonate is 0.04mol/L.The LiNi0.5Mn1.5O4 modification was used of F,Cr/F, La/F,Co/Fe/Cl ion common doping, Using XRD, SEM and constant current charge and discharge, CV and EIS tes t means for materials characterization, etc. Characterization results: All the peaks are a ttributed to the typical peaks of cubic spinel structure. When the F-doped LiNi0.5Mn1.5O4-xFx,doping amount of x=0.02 have high discharge capacity and rate cycling stability;Cr / F doping Li Ni0.5-xMn1.5-y Crx+y O4-zFz, when the x = 0.02, y = 0.02, z = 0.05, the material have high rate cycling stability;La / F doping Li Ni0.5Mn1.5O4,Li Ni0.49Mn1.49La0.02O3.92F0.08 has the highest charge-discharge capacity, rate cycle stability;Respectively use F, Cr / F, La / F and Fe / Co / C on Li Ni0.5Mn1.5O4 modified,using XRD, SEM, constant current charge and discharge, CV, EIS and other testing m ethods for materials characterization. Characterization results: XRD pattern of the test r esults with standard materials prepared consistent, belonging cubic spinel structure. Wh en the F-doped LiNi0.5Mn1.5O4-xFx, when high discharge capacity of the material when x = 0.04, the rate cycling stability; Cr / F doping LiNi0.5-xMn1.5-yCrx+yO4-zFz, when the x = 0.02, y = 0.02, z = 0.05, the discharge capacity of the material high rate cycling stability. La / F doping LiNi0.5Mn1.5O4, LiNi0.49Mn1.49La0.02O3.92F0.08 has the highest c harge-discharge capacity, rate cycle stability; Co, Fe, Cl doping Li Ni0.5Mn1.5O4, LiNi0.47Mn1.47Co0.02Fe0.04O3.92Cl0.08 has the highest charge-discharge capacity, rate cycle stability.Use of Al2O3, LiV3O8 coated on LiNi0.5Mn1.5O4 modified, XRD test results show that the structure of the material before and after coating does not change, the use of the material prepared when Li V3O8 were coated modified, when coated amount of3%,the material in the process of magnification exhibit very good stability of the cyc le, after the completion of magnification exhibits excellent reversibility. When using m aterials prepared Al2O3 be coated modified, performed after the coating material Al2O3 increased specific capacity, excellent rate performance, and stable cycle characteristics.The material was prepared by doping coated common modification, Al2O3 coated Li Ni0.49Mn1.49La0.02O3.92F0.08, the coating amount of Al2O3 was 0.5%,the materials has t he best electrochemical performance, Al2O3 coated Li Ni0.46Mn1.46Co0.04Fe0.04O3.92Cl0.08, th e capacity and rate cycle performance was improved... |
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