A niobium-doped lithium-rich manganese-based layered oxide cathode material and a preparation method thereof

Abstract

The invention discloses a niobium-doped lithium-rich manganese-based layered oxide cathode material, which has the chemical formula of Li1.20-XNbxMn0. 54Co0. 13Ni0. 13O2 (0 <= x <= 0. 10). The invention adopts a polymer template method to prepare, the main steps are as follows: the dried cross-linked poly (acrylamide-methacrylic acid) microspheres are immersed in an aqueous solution containing Mn2+, Co2 + and Ni2 + ions of urea, the solution is adsorbed completely, and then heating and drying are performed; the dried microspheres are added into a solution containing lithium salt and niobium salt, heating is performed to remove moisture, and obtaining a lithium-rich cathode material precursor is obtained; the obtained precursor is calcined in air at high temperature to obtain a product-Niobium-doped lithium-rich manganese oxide base cathode material. As that crosslink polymer microsphere is used as a template, the transition metal hydroxide nanoparticle are synthesized in situ, the morphology of the lithium-rich manganese base oxide positive electrode material can be effectively regulated and the electrochemical performance can be greatly improved, and the preparation process of the niobium-doped lithium-rich manganese-based layered oxide cathode material is simple, the particle morphology is good in reproducibility, and the niobium-doped lithium-rich manganese-based layered oxide cathode material is suitable for industrial production.

Description

technical field [0001] The invention relates to the technical field of electrochemistry, and more specifically relates to a niobium (Nb)-doped lithium-rich manganese-based layered oxide cathode material and a preparation method thereof. Background technique [0002] Economic take-off has brought energy distress, fossil energy shortage, and serious pollution. Therefore, the research and utilization of green and renewable new energy sources have gradually attracted widespread attention around the world. Among them, chemical power sources can efficiently convert and store energy, which is conducive to breaking through the limitations of natural energy regions and time, and improving its utilization more reasonably, such as solar cells. Lithium-ion battery, a new green power source, has many advantages such as high capacity, high voltage, safety, and environmental protection. It is mostly used in portable devices and is the most promising energy device. However, in order to exp...

AI Technical Summary

Problems solved by technology

However, when charged above 4.5V for the first time, the Li 2 MnO 3 out of Li 2 O is accompanied by the release of oxygen, and the liberated Li 2 O cannot reversibly embed back into the lattice of LMLO materials, which leads to the problems of large irreversible capacity, low initial Coulombic efficiency and continuous decrease of discharge voltage in this kind of cathode materials.

In addition, Li 2 MnO 3 Low electronic conductivity leads to low rate capability of LMLO materials

Therefore, the problems of low initial Coulombic efficiency, continuous decrease in discharge voltage during cycling, and poor charge-discharge rate performance have seriously hindered the practical application of lithium-rich manganese-based layered oxide cathode materials in power lithium-ion batteries.

[0004] In order to solve the above problems, researchers have carried out a lot of research work and adopted the following methods: coating electrochemically inert substances, conductive polymers, solid lithium ion conductors or electrochemically active substances on the surface of LMLO particles; Material recombination; chemical pretreatment; bulk cation doping or anion doping; synthesis of layered / spinel heterostructure materials, or concentration gradient core-shell materials; micro / nano electrode materials; forming on the surface of material particles Oxygen vacancies, etc., but the above methods can only solve one or two of the problems, and cannot solve all problems

[0005] Therefore, how to provide a lithium-rich manganese-based layered oxide cathode material and its preparation method that can simultaneously solve the problems of low initial coulombic efficiency, discharge voltage attenuation, and poor rate performance is the research direction of those skilled in the art.

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