An Investigation On The Preparation And Properties Of Vanadium-based Oxides Electrode Material For Lithium-ion Battery

In 1957,Wadsley studied and reported the lithium vanadium oxides cathode materials with a layered monoclinic structure?P2₁/m?for the first time.Because it has many advantages such as facile preparation as well as high specific capacity,thus it can be used in both cathode materials in organic electrolyte system and anode materials in aqueous electrolyte system.However,because of its poor rate capability,bad cycle stability and low conductivity,the application of vanadium is still limited.Considering these shortcomings,we adopt a series of methods to enhance the electrochemical properties of LiV₃O₈ materials.At first,an oxalic acid sol-gel method was used to synthesize a series of Li_1-xNa_xV₃O₈?x=0,0.05,0.1,0.2,0.4?nanorods.The results shown that in the organic electrolyte system,the discharge capacity retention rates of material rate performance test were:35.02%,49.15%,70.44%,34.7%,29.67%respectively,and the capacity remaining of the cycling stability displayed that 60.7%,77.7%,87.5%,62.7%,59%respectively,at the current density of 0.1 C.The same results were appeared in aqueous lithium ion battery,and specially,when the doping amount of Na⁺was 0.1,the electrochemical performance of electrodes were improved obviously.In addition,we adopted oxalic acid sol-gel method to prepare Mn substitute V,so a series of nanorod LiV_3-xMn_xO₈?x=0,0.025,0.05,0.1?materials were observed.The results indicated that when the doping amount of Mn⁴⁺was 0.05 in the organic electrolyte system,the discharge capacity retention rate are 44%at the current density of 5 C of rate capability tests.Meanwhile,its capacity retention was 66%for 0.1 C cycle performance tests.The same results were appeared in aqueous lithium ion battery,and when the doping amount of Mn⁴⁺was 0.05,the high rate discharge performance and the cycle performance of electrode materials would be improved obviously.At last,we report a novel strategy for enhancing lithium ion transport by building superionic pathways on the surface of Li_0.85Na_0.15V₃O₈ nanosheets.The two-dimensional nanosheets were constructed by using a modified glycin acid sol-gel strategy and the electrode displayed a high rate capability of 172.3 mAh·g^-1 at 5 C and an excellent cycling stability of retaining 98.9%after fifty cycles.Therefore,the strategy by building superionic pathways on the surface of Li_0.85Na_0.15V₃O₈ nanosheets will be good for achieving high-performance LiV₃O₈ electrode material.