Lithium-manganese-aluminum oxygen anode material and preparation method thereof

Abstract

The invention provides a lithium-manganese-aluminum oxygen anode material, which has the atomic ratio of LiaMn2-x-yAlxMyO4; the concentration of A1 is in a gradient distribution presenting gradually risen from the inner part of the lithium-manganese-aluminum oxygen anode material to the surface; the concentration of Mn is in a gradient distribution presenting gradually decreased from the inner part of the lithium-manganese-aluminum oxygen anode to the surface. The invention further provides a preparation method of lithium-manganese-aluminum oxygen anode material. By adding solution or turbid liquid of aluminum source compound in the precipitation process, the aluminum element replaces the position of a manganese element in the formed lithium-manganese-aluminum material, so that the spinel structure of the lithium-manganese-aluminum material is stabilized, the forming of the lattice defect is avoided and the well high-temperature circulating performance of the lithium-manganese-aluminum material is guaranteed, the dissolution of manganese in the electrolyte is reduced and the high-temperature circulating performance of the lithium-manganese-aluminum oxygen anode material is further improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium-manganese-aluminum-oxygen cathode material and a preparation method thereof. Background technique [0002] As a new type of energy storage system, lithium-ion batteries have the advantages of good safety, high discharge specific energy, and long charge and discharge life. They have been widely used in digital products, electric tools, and electric bicycles. Lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate have been commercially produced as positive electrode materials for lithium ion batteries. However, lithium cobalt oxide is expensive and has poor safety performance; lithium iron phosphate has poor filling performance and low volume specific energy Although lithium manganate has the advantages of high discharge voltage, low price, abundant reserves, and high safety performance, its high-temperature cycle performance is poor, which...

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Problems solved by technology

Since this method uses high-temperature diffusion to make the coating elements enter the crystal lattice of the lithium manganate material, it has the following disadvantages: First, the high-temperature diffusion method will cause the coating elements to enter the crystal lattice of the lithium manganate material during the diffusion process. In the lattice gap, it leads to the generation of lattice defects, which affects the cycle performance of lithium manganese oxide materials

Secondly, there is a direct proportional relationship between the diffusion depth of the coating element and the synthesis temperature. The higher the synthesis temperature, the deeper the diffusion depth of the coating material and the thicker the coating layer. Since the synthesis temperature of the material cannot be too high, the gradient formed by high temperature diffusion The thickness of the layer is generally only 1-2 μm, which cannot effectively block the corrosion effect of the electrolyte on the lithium manganate material, so that the Mn in the lithium manganate material 2+ Easy to dissolve, thus affecting the cycle performance of lithium manganate materials

Again, the surface layer of the lithium manganate material formed by this high-temperature diffusion method is the oxide layer of the coating material, which is not conducive to the migration of lithium elements between the material and the electrolyte, and is also not conducive to the migration of electrons between the material and the aluminum foil. The rate performance of the lithium manganese oxide material is poor

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