Preparation And Electrochemical Performances Of LiMn₂O₄ And LiNi_0.5Mn_1.5O₄ Nanofibres

Compared to many cathode materials,the spinel LiMn₂O₄ has immense promise as cathode material for lithium-ion batteries because of its lower cost,higher voltage,more environmentally friendliness,safer than Li NiO₂ and LiCoO₂ cathode materials.Prepared cathode material nanofibres through sol-gel and electrospinning method for lithium-ion batteries,and studied the structure,morphology and electrochemical performances of the material.In the experiment,acetate was used as the raw materials,distilled water and DMF were used as the solvent,PVP was used as the binder with an appropriate molar ratio prepared the precursor.The LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ nanofibres were successfully prepared by electrospinning technique,and being annealing at 400?⁸00?.Then accessory materials were performed into coin-type Li battery in the glove box and sequentially assembled.This experiment used modern analytical methods,such as X-ray diffraction?XRD?,Electron microscopy?SEM?,Land cell tester and AC impedance tester to analyse the structure,morphology and electrochemical performances of the nanofibres.The LiMn₂O₄ nanofibres were prepared by electrospinning technique combined with annealing,and the nanofibres had a smooth morphology and the single phase with high crystallinity after being annealing at 700?.The XRD revealed that the LiMn₂O₄ nanofibres possess a spinel structure.SEM images showed the diameter of LiMn₂O₄ nanofibres was 350 nm.The initial charge capacity and discharge capacity were 114.1 mAh g-1 and 112 mAh g-1 at 0.1C,respectively.And discharge capacity was 109.1 mAh g-1,101.9 mAh g-1,91.3 mAh g-1 and 80.6 mAh g-1 at 1C,2C,5C and10 C,respectively.Capacity retention of 92.7% after 100 cycles under 1C.The CV showed the characteristic two-step redox peaks at 3.92/4.10 V and 4.05/4.22 V,which are characteristic peaks of LiMn₂O₄.The EIS spectrum showed the charge-transfer resistance Rct of LiMn₂O₄ was 615.40 ?.The Li Ni_0.5Mn_1.5O₄ nanofibres were prepared by electrospinning technique combined with annealing,and the nanofibres had a smooth morphology and the singlephase with high crystallinity after being annealing at 700?.The XRD revealed that the Li Ni_0.5Mn_1.5O₄ nanofibres possess a spinel structure.SEM images showed the diameter of Li Ni_0.5Mn_1.5O₄ nanofibres was 250 nm.The initial charge capacity and discharge capacity were 183.8 mAh g-1 and 138.4 mAh g-1 at 0.1C,respectively.And discharge capacity was 135.2 mAh g-1,113.3 mAh g-1,75.4 m Ah g-1 and 19.3 mAh g-1at 1C,2C,5C and 10 C,respectively.Capacity retention of 94.2% after 100 cycles under 1C.The CV showed the characteristic two-step redox peaks at 3.96/4.10 V and4.60/4.82 V,which are characteristic peaks of LiNi_0.5Mn_1.5O₄.The EIS spectrum showed the charge-transfer resistance Rct of LiNi_0.5Mn_1.5O₄ was 347.13 ?.Compared to LiMn₂O₄ and Li Ni_0.5Mn_1.5O₄,indicated that the doping element Ni can improve the crystallinity of the material but do not affect the formation of a spinel structure,the diameter of nanofibres can decrease by 100 nm,the capacity and rate performance of materials were improved,the capacity retention improved about 1.5%was obtained after 100 cycles under 1C,and increased the energy density of battery with improved the charge-discharge voltage platform,the Rct value of material can decrease by 268.27 ?.