Modification On Li-rich Manganese-based Cathode Material For Vehicle Power Battery

Li-rich cathode material Li1.2Ni0.13Co0.13Mn0.54O2 have big specific capacity（250～350 m Ah/g）,and can well satisfy the lithium-ion batteries in the small electronic products and used in the field of electric vehicles and other requirements,is the most potential one of the next generation of power lithium ion battery cathode material.Li-rich cathode material Li1.2Ni0.13Co0.13Mn0.54O2 used in high temperature solid method preparation.Li-rich cathode material for a-Na Fe O2 type structure,R3m space group,as to the hexagonal system.Study the effects of temperature as its function of the composite material,and use of industrial raw materials of lithium manganese,nickel,cobalt salt and salt salt synthesis rich lithium manganese anode material,by improving the calcination time and calcination temperature,the electrochemical properties and better rich lithium manganese anode material.This calcination temperature is 900℃discharge specific capacity for the first time in 0.1 C ratio of 0.1 m Ah g^-1,circulation capacity remain at a rate of 96.76%after 60 times.Doping Al³⁺Li-rich manganese-based cathode material after its discharge specific capacity gradually with the increase of charging and discharging rate is higher than the original sample.Under the 3C ratio Li1.2Ni0.13Co0.13Mn0.54O2 discharge specific capacity fell sharply to 100 m Ah g^-1,Li1.2Ni0.13Co0.13Alx Mn0.54-x O2（x=0.02）to 231 m Ah g^-1,which improves the performance ratio.Li1.2Ni0.13Co0.13Mn0.54O2 discharge specific capacity dropped significantly in the process of charging and discharging cycle,cycle capacity remain at a rate of 73.33%after 100 times,but after doping Al³⁺sample cycle capacity remain at a rate of 97%after 100 times.Show that doping Al³⁺after Li-rich manganese-based cathode material to improve the cycle stability.Fe³⁺doped Li-rich manganese-based cathode material make material interplanar spacing increases,promoted the rapid diffusion.In addition,the charging and discharging process of Fe³⁺doped material has better structural stability may show lower cells impedance,which will be conducive to the charge and discharge process.Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ before charging and discharging,electrode,828.3ΩRct resistance and Li_1.2Ni_0.13Co_0.13Fe_0.02Mn_0.52O₂ electrode showed a smaller 168.4ΩRct resistance value.Circulation after 50 cycles,all the samples of Rct resistance is greatly reduced,and its electrochemical activation,including Li1.2Ni0.13Co0.13Fe0.02Mn0.52O2 Rct of electrode resistance value is 92.6Ω,compared Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ electrode217.1Ωbecome smaller.Cycle to course for charging and discharging Li1.2Ni0.13Co0.13Fe0.02Mn0.52O2 electrode has a more stable electrolyte/electrode interface,to reduce the Rct resistance value,improve its conductivity.If Cr³⁺doping amount is on the rise,material of the discharge specific capacity is on the rise,explain Cr³⁺doping positive pole material Li1.2Ni0.13Co0.13Mn0.54O2 shows better for discharge specific capacity,which respectively in different ratio of 0.1 C,0.2 C and0.5 C and 1 C and 2 C loop 100 times,Li1.2Ni0.13-x/3Co0.13-x/3Mn0.54-x/3Crx O2（x=0.02）of discharge specific capacity were 332.11 m Ah g^-1,308.86 m Ah g^-1,191.56m Ah g^-1,271.06 m Ah g^-1 and 113.92 m Ah g^-1,shows that after doping Cr³⁺can improve the ratio of material performance.Finally,this paper in the Li-rich manganese-based cathode material doped with a small amount of Cu²⁺,charge and discharge on 0.1 C ratio,material Li1.2Ni0.13Co0.13Mn0.54O2 and Li1.2Ni0.11Co0.11Mn0.53Cu0.05O2 cycle capacity were 308.2m Ah·g^-1 and 271.5 m Ah·g^-1,the first cycle charge-discharge efficiency of 83.02%and84.01%respectively,explain Li1.2Ni0.13Co0.13Mn0.54O2 raised in the first week after doping Cu²⁺material circulation irreversible capacity loss.