Ni substitution effect on the performance of lithium ion battery materials LiMnTiO4 have?

Source: 2020 - 04 - 11 they which hits: time of nickel substitute effect on the performance of lithium ion battery materials LiMnTiO4 a new generation of chemical energy, lithium ion secondary battery with high energy density, power density, high voltage, low self-discharge rate, no memory effect, light weight, no pollution and other unique advantages, quickly became the most promising new type of battery. Lithium ion battery cathode material will directly affect the performance of lithium-ion batteries. At present, the commercial anode materials include LiCoO2 layer, 3 mn1 lini1/3 co1 / o2/3, olivine LiFePO4 and spinel LiMn2O4. Spinel LiMn2O4 has the advantages of cheap raw material, non-toxic, high pressure platform. But its capacity to attenuation in the charging and discharging cycle, mainly due to the following reasons: 1) Electrolyte on the surface of Mn3 + disproportionation reaction and acid corrosion lead to the dissolution of manganese, lead to Mn2 + dissolve into the electrolyte, lead to capacity loss; 2) Jahn - caused Mn3 + The teller effect. Ginger Taylor effect lead to the crystalline structure of the cubic phase transformation and phase, the increase of the lattice parameter c/a value and contraction and expansion of large structure, hindered the lithium ion transport channel, destroyed the spinel lattice, and loosen the contact between the particles, leading to the difficulty of li + disentrainement. Improve electrode materials circulation performance generally there are two ways: one is coated on the surface of the anode material, mainly in the surface active material coating a layer of oxide or oxide particles, and lithium battery electrolyte small contact area between the positive active material, reduce the electrolyte decomposition, improve the cycle life of material at high temperature; Second, doping modification, also called internal structure modification. Doping modification including cation doping, anion and mixed ion doping. Geng and others, for example, by using the template method to Al doping limn1. 5ni0. 5 in m1, found that Al can enhance the stability of the material, improve the capacity of the materials. LIU, and others use B instead of the 10% of LiMnPO4 ( Atomic ratio) P, significantly improve the cycle performance of electrode and the high performance of multiplier. The amount of anion and cation of al F composite doping can improve Li ( ni1/3 co1/3 mn1/3) The crystallinity of O2, improve its layered structure. Thus greatly improve the performance of the cycle. For LiMn2O4 materials, by adding the appropriate structure elements can be stable material, inhibit the dissolution of manganese, inhibit jahn - The teller effect. In recent years, the study found that [ 8 - 9] , the Ti4 + by replacing the LiMn2O4 Mn4 +, can effectively restrain jahn - The teller effect. TiO 键键能为662kJ/mol, 高于MnO 键的402 kJ/mol, 能形成更稳定的[ Mn2 - xTix] M1: structure, thus inhibiting Jahn - The Teller effect. In addition, Ti replace can recover part of Mn3 + Mn2 +, reduce the concentration of Mn3 + In ginger Taylor effect, and increase the discharge capacity and inhibition of ginger Taylor effect, but the theoretical discharge capacity. There is still a gap in the study of the spinel LiMn2O4 found that Ni Mn (replacement LiMn1。 5Ni0. 5O4) Increase the discharge capacity and cycle stability of the electrode materials [ 10 - 11] 。 In order to improve the discharge capacity of LiMnTiO4, using sol-gel Gel prepared LiMnTiO4 ( x= 0,0. 1, 0. 2, 0. 3) , and combined with solid instead of LiMnTiO4 Ni should be studied to replace the effect of electrochemical performance. Conclusion 1 copyright reasons more content please see the academic network) Ni displacement unchanged LiMnTiO4 spinel structure and morphological characteristics of Ni replacement did not produce the phase-out of associated with replacement elements. Ni used instead of Mn. The number of replacement should not be too much. If replace the amount is too large, the charge and discharge potential of electrode materials will significantly lower. 3) When Ni replace quantity to zero. 1, LiMnTiO4 electrochemical performance is obviously improved. LiMn0 after 48 cycles. 9Ni0. 1 tio4 discharge capacity is 162. 8 mah/g, retention capacity for 82. 7%. This is mainly due to the nickel replace REDOX process after the electrode polarization is reduced, is advantageous to the electrochemical reaction.