Multiphase Mn (manganese)-base anode material and preparation method thereof

Abstract

The invention provides a multiphase Mn (manganese)-base anode material, which is of a three-phase composite structure comprising a kernel, an intermediate layer and a surface layer. The chemical formula of the anode material is shown as x(Li2MnO3).(LiNi0.3Mn0.7O2).y(MO), wherein x is more than or equal to 0.01 and less than or equal to 0.1, y is more than or equal to 0.01 and less than or equal to 0.1 and M is one selected from Cu, Zn or Mg. A preparation method of the anode material comprises the following steps: adopting a liquid phase precipitation reaction to prepare Ni0.3Mn0.7(OH)2 and precipitating the precursor of Mn(OH)2 on the surface of the Ni0.3Mn0.7(OH)2; mixing the precursor with lithium carbonate, and carrying out a solid-phase reaction to prepare a two-phase composite material x(Li2MnO3).(LiNi0.3Mn0.7O2); and finally adopting a liquid phase precipitation method to adhere a layer of metallic hydroxides to the surface of x(Li2MnO3).(LiNi0.3Mn0.7O2) and heating and decomposing to obtain MO. The preparation method is simple and convenient to operate; the components and the contents of the prepared multiphase Mn-base anode material can be controlled; the uniformity of the kernel components is good; and the prepared multiphase Mn-base anode material is high in capacity, first coulomb efficiency and safety and long in cycle life and is suitable for industrialization production.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and relates to a multiphase manganese-based positive electrode material and a preparation method thereof. technical background [0002] Lithium-ion batteries have the advantages of high energy density and good cycle performance, and are widely used in portable electronic devices. Most commercial lithium-ion batteries use LiCoO2 as the positive electrode material. Because lithium cobalt oxide uses scarce cobalt resources, resulting in high material costs, in addition, its energy density is limited. In recent years, researchers have devoted themselves to finding materials that can replace lithium cobalt oxide. An important breakthrough is the discovery of x(Li2MnO3)·y(LiNi0.5Mn0.5O2) composite materials with a solid solution structure by Argonne National Laboratory in the United States. It has the advantages of relatively low cost and high capacity at high battery voltage, and has become one ...

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Problems solved by technology

Although this type of material has significant advantages, there are still quite a few problems to be solved: 1) The material needs to be used under high voltage, which causes the electrolyte to decompose on the surface of the material, resulting in low coulombic efficiency of the battery for the first time, which is not conducive to the use of the material in the battery. Capacity; 2) Under high voltage, the electrochemically active elements in the material are processed in a high-valence state, which is prone to oxygen loss reaction, causing safety hazards to the battery; 3) In the solid solution structure, the composition of Li2MnO3 is sintered at high temperature produced in the process, the proportion of its content in the whole material cannot be stably controlled, that is, the controllability of each phase composition is poor; 4) When synthesizing the positive electrode material, it is necessary to prepare the nickel-manganese hydroxide precursor first, because manganese, nickel The solubility product constants of hydroxides vary greatly, and it is difficult to prepare a uniformly mixed precursor of nickel and manganese, which affects the performance of the final cathode material

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