| Spinel Li1+xMn2O4 was prepared using LiOH·H2O and Mn(CH3COO)2·4H2O as raw materials by sol-gel method.The structure and performance of the spinel were studied.The results show that prepared sample has uniform cubic spinel structure.Electrochemical measurements show that the sample has high specific capacity and good cyclic performance.The modifications of spinel LiMn2O4 by anion(S2-,F-)doping were investigated.XRD test show that S-doped and F-doped samples have fine cubic spinel structure.Electrochemical measurements show that cyclic performance was improved by anion doping.Doping S can stabilize the structural integrity of the spinel host,and overcome Jahn-Teller distortion during charge/discharge cycles. The Li1+xMn2O3.98S0.02sample show a first discharge capacity of 122 mAh·g-1with very small capacity loss and the retention capacity above 98%at 0.1C,performed continuously 20 cycles under 0.2C,0.4C and 0.8C the final capacity is 110 mAh·g-1,the capacity fading rate was 9.8%.Doping F can improve structure stability of the sample.Because of doping F cannot inhibit Jahn-Teller distortion,the improvement of cyclability was not significant by F-doped.The PVDF-HFP based gel polymer electrolyte was prepared,studied the effects of different amounts of various components on the polymer performance. The results show that the addition of nano SiO2,Al2O3 and HZSM-5 can improve properties of electrolyte.The highest conductivity of the nano-SiO2/LiClO4/PVDF-HFP composite gel polymer electrolyte is 7.56×10-3S/cm when PVDF-HFP:LiClO4: nano SiO2:plasticizers=1:0.8:0.08:5.Then the electrochemical stability window was above 4.8V,the ion transference number was 0.67.The batteries were assembled using lithium metal as an anode,synthesized Li1+xV3O8,LiFePO4 and Li1+xMn2O4 as cathode,nano-SiO2/LiClO4/PVDF-HFP as electrolyte film.The charge/discharge tests show that the polymer lithium batteries have high specific capacity and good cyclic performance.
|
PDF Full Text Request