High-density spherical Ni-Co lithium aluminate material and preparation of precursor of the material

Abstract

The invention relates to a method for preparing a Ni-Co-Al precursor material and a method for preparing a Ni-Co lithium aluminate material with the precursor material. The method for preparing the Ni-Co-Al precursor material comprises following steps: (1) preparing a solution A containing a nickel (II) salt and a cobalt (II) salt, a solution B containing an aluminum complex and an ammonia-containing inorganic strong alkali solution C, wherein the solution B is prepared by dissolving an inorganic aluminum salt and at least two complexing agents; (2) synchronously feeding the solution A and the solution B into a reactor with a flow speed controlled to enable a molar ratio of nickel ion, cobalt ion and aluminum ion to be (6-9):(0.5-2):(0.5-2) with addition of the solution C to maintain a pH value of the mixture system to be 10-12.7; and (3) after the solution A and the solution B are fed synchronously, performing solid-liquid separation and washing, drying and optionally sieving a separated solid product to obtain the Ni-Co-Al precursor material.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular to the preparation of a high-density spherical nickel-cobalt lithium aluminate material and its precursor. Background technique [0002] At present, lithium-ion batteries have been widely used in various mobile appliances, such as mobile phones, cameras, and notebook computers. The demand for lithium-ion secondary batteries with high performance and good safety performance continues to increase. LiNiO 2 The positive electrode material doped with Co element also has LiNiO 2 The high discharge specific capacity of the material stabilizes the layered structure of the material and enhances the cycle performance of the material. The representative material can be expressed as LiNi 0.8 co 0.2 o 2 , the positive electrode material with this composition has a better energy density than the same series of materials. However, this material also has d...

AI Technical Summary

Problems solved by technology

[0007] The preparation method of nickel-cobalt-aluminum material disclosed in patent application 200810052730.0 is to directly carry out co-precipitation reaction between nickel-cobalt-aluminum salt solution and alkali solution. Although this method is relatively simple and suitable for industrial production, because trivalent aluminum precipitates quickly and easily in the co-precipitation process Colloids are formed, resulting in incomplete crystallization of the nickel-cobalt-aluminum precursor, irregular shape, low tap density and poor electrical properties; although the method disclosed in patent application 201110140341.5 can prepare a better shape and higher tap density Nickel-cobalt-aluminum precursor and material, but the aluminum element in the material prepared by this method is coated on the surface of the nickel-cobalt precursor, part of the aluminum cannot enter the lattice during the firing process, and nickel, cobalt, and aluminum ions cannot form atoms Level mixing affects the performance of the material; the method disclosed in the patent application 201010594744.2 can oxidize all ions during the preparation of the precursor to form a trivalent spherical nickel-cobalt-aluminum oxyhydroxide precursor, so that the shape of the precursor is regular and the tap density is high , but the strong oxidant in the liquid phase will cause a large number of impurity ions to enter the crystal lattice, which will greatly increase the impurity of the material, and this impurity cannot be removed by washing, which is unacceptable in commercial applications

The nickel-cobalt-aluminum preparation method proposed by ACS Appl.Mater.Interfaces2012, 4, 586-589 can improve the crystallinity of the precursor material, which is conducive to the improvement of the physical and chemical properties of the material, but the preparation process of this method is relatively complicated, and too many organic solvents are used for follow-up The processing difficulty increases, and the organic aluminum source raw materials used are expensive and cannot meet the needs of large-scale production

Images