Preparation Of LiNi_xCo_yMn_1-x-yO₂ For Lithium-Ion Batteries And Study Of Their Full Cell Performance

Lithium-ion batteries with more higher energy density is required for the rapid development of Electric Vehicles.Ternary cathode materials,as the ideal cathode materials for lithium ion batteries,are the research hotspot.Focused on the development of ternary cathode materials with better electrochemical performance,in this paper,we prepared two ternary cathode materials:the LiNi0.8Co0.1Mn0.1O2 with high capacity prepared by coprecipitation and calcination method,and the one-dimensional(1D)LiNi1/3Co1/3Mn1/3O2 cathode with high-rate prepared by a template method.Furthermore,a full-cell with high-power was constructed using LiNi1/3Co1/3Mn1/3O2 as cathode and Li4Ti5O12 as anode.Spherical precursors Ni0.8Co0.1Mn0.1(OH)2 were successfully synthesized by coprecipitation.LiNi0.8Co0.1Mn0.1O2 was synthesized using lithium hydroxide as lithium source combined with high-temperature calcination.The effects of ammonia concentration on the morphology,composition and tap density of the precursor,and the effects of calcination temperature and lithiation ratio on the physicochemical properties and electrochemical properties of LiNi0.8Co0.1Mn0.1O2 cathode materials were investigated.As a result,with the increase of calcination temperature,the capacity of LiNi0.8Co0.1Mn0.1O2 increases but the cycle stability deteriorates.Moreover,the reversible capacity of LiNi0.8Co0.1Mn0.1O2 reduced,but the cycle stability improved with the increased lithium-supply.Excellent performance is achieved for the LiNi0.8Co0.1Mn0.1O2 prepared at 750℃ with 5%excess lithium supply,which performs a low Li/Ni mixing degree,and a high capacity of 177.6 mAh g-1 at 0.2C,and 100.9 mAh g-1 at 10C,moreover,73.0%capacity is retained even after 200 cycles at 5 C.The 1D Ni1/3CO1/3Mn1/3C2O4 precursor was firstly prepared by a coprecipitation method using cobalt oxalate nucleus as template,after mixed with lithium carbonate and underwent a high-temperature calcination process,the 1D LiNi1/3CO1/3Mn1/3O2 is obtained.The influence of nucleation duration time on the morphology and structure of the Ni1/3Co1/3Mn1/3C2O4,and the effect of calcination temperature on the morphology and structure of the LiNi1/3Co1/WMn1/3O2 were explored.The results show that LiNi1/3Co1/3Mn1/3O2 prepared with the cobalt oxalate nucleation for 6 h,and calcination temperature at 800℃ has uniform one-dimensional morphology.The initial discharge capacity is 163.9 mAh g-1 at 0.1C,and 120.1 mAh g-1 is maintained at 10C.The full-cell with high-power was constructed with high-rate 1D LiNi1/3Co1/3Mn1/3O2 as cathode and commercial Li4Ti5012 as anode.The effects of potential range,and anode/cathode capacity ratio(NP ratio)on the performance of the full-cell were studied.The results show that the LiNi1/3Co1/3Mn1/3O2-Li4Ti5O12 full-cell with a NP ratio of 1.05 has an initial reversible capacity of 164.4 mAh g-1 at 1C with a potential range of 1.5-3.5 V.The capacity retention rate is 98.5%after 60 cycles,furthermore,even at a high current density of 10C,a high capacity of 140.3 mAh g-1 is maintained.A high energy density of 169 Wh kg-1 is achieved at a power of 2111 W kg-1 based on the mass of the active material.