Synthesis And Antimony Doping Of Lithium-Rich Layered Materials

Lithium ion batteries become the main energy storage devices of modern mobile electronic devices,hybrid and electric vehicles and smart grid due to its few advantages such as high efficiency,environmental friendly and high energy density.Li-rich(LLMO)layered materials have attract wide attention of researchers over the past few years due to its high theoretical specific capacity(300 mAh g-1).However,the material also has disadvantages such as low coulomb efficiency,poor rate performance and voltage decay upon cycling.In this paper,we synthesis 0.5Li2Mn03 0.5LiNi0.33CO0.33Mn0.33O2 material by coprecipitation method and sovolthermal method to control the evenly distribution of components and structure.and the antimony ion doping modification has also researched to enhance the stability of the layered strcuture.The main content is followed:Li-rich layered materials has been successfully synthesized by coprecipitation method,the oxalate is used as precipitant,and the effects of different precipitation agents/transition metals on the materials were discussed.The results show that the synthesized LLMO cathode material has excellent structural stability and electrochemical performance while the ratio is 2:1.It delivers 300.2 mAh g-1 at 0.1 C,with coulomb efficiency of 75.4%.The influence of the excess lithium amount,calcining mechanism,precipitant ratio and concentration on the materials was investigated by solvothermal method.Results show that the morphology of the LLMO-C1 is porous hollow prism structure under the ratio of complexing agent/transition metal of 2.5:1,excess lithium amount of 5%,concentration of 0.2 M by one-step calcine(plan A).The structure is stable and exhibites the best electrochemical properties,the initial discharge capacity reached 295.3 mAh g-1 at 0.1 C with the first coulombic efficiency of 80.9%,and it delivers 150.6 mAh g-1 even at 5C.It is the one-dimensional growth of prism architecture with partial interconnected polygon particles can not only decrease the unnecessary contact area,but also provide a short distance for ion diffusion along the confined radial dimension.The antimony ion is successfully doped into Li-rich layered material by solvothermal method,the doping amount of 0.5%and 1%samples exhibit higher first discharge capacity compared with un-doped samples.The initial discharge capacity of LLMO-Sb1(1%)deliver 333.6 mAh g-1,and the capacity retention rate was 99.2%after 100 cycles.Moreover,the doping amount of 1 mol%sample can also greatly inhibited the voltage decay which shows no attenuation after 100 cycled.X-ray diffraction,scanning electron microscopy,X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis indicate that High resolution transmission electron microscopy(HRTEM),fast Fourier transform(FFT),X-ray photoelectron spectroscopy(XPS)analysis represents the strong Sb-O can inhibit the oxygen consumption,the larger ionic radius of Sb3+ also effectively expand the(003)spacing,reduced the dynamic barrier of lithium ion migration,thus The results here will shed light on improving the electrochemical capacity,stabilizing the lattice and increasing rate performance for high-performance lithium ion batteries.