Doped Li/Ni/Mn/O material and preparation method thereof as well as lithium ion battery

Abstract

The invention discloses a doped Li / Ni / Mn / O material and a preparation method thereof as well as a lithium ion battery. The method comprises the following steps: (1) immersing a LiNi0.5Mn1.5O4 material into a metal M salt solution to be doped; taking out the material and drying to obtain a precursor; and (2) firing the precursor under an inert atmosphere to obtain the doped Li / Ni / Mn / O material. The doped Li / Ni / Mn / O material prepared by the preparation method is used as a positive electrode material and has better conductivity, capacity retention ratio and rate capability. The preparation method has a simple preparation process and the prepared product has good homogeneity and can be put into industrial production easily. According to the preparation method, the material to be doped enters crystal lattices of an active material, namely the Li / Ni / Mn / O material, so that the aim of being doped in the Li / Ni / Mn / O material is realized. Meanwhile, the thickness of the doped material covering the surface of the active material, namely the Li / Ni / Mn / O material is reduced, so that the use amount of the covered doped material is reduced and the resistance can be reduced when lithium ions come in and go out of the positive electrode active material.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a doped lithium nickel manganese oxide material, a preparation method thereof, and a lithium ion battery. Background technique [0002] In recent years, with the increasingly serious energy and environmental problems and the requirement of light weight electronic products, people's research on lithium-ion batteries has been deepening. At present, the commonly used commercial lithium-ion battery cathode materials mainly include the following categories: lithium cobalt oxide materials, lithium manganese oxide materials, and lithium nickel manganese oxide materials. Lithium cobalt oxide (LiCoO 2 ) The price of materials is high, and the raw materials used for its preparation are toxic, and people have been working hard to develop their substitutes; lithium manganate (LiMn 2 o 4 ) materials have attracted people's attention because of their low price and ...

AI Technical Summary

Problems solved by technology

[0003] Although LiNi 0.5 mn 1.5 o 4 The material has many advantages as a positive electrode material, but its voltage is relatively high (about 5v) during the charge and discharge process, which will cause Mn 3+ A disproportionation reaction occurs, and the generated Mn 2+ Soluble in electrolyte, Mn 2+ And diffuse to the surface of the negative electrode carbon material, resulting in the irreversible capacity loss of the battery material and affecting the battery efficiency

When using LiNi 0.5 mn 1.5 o 4 The battery system using LiFP as the cathode material 6 When using the electrolyte solution of the electrolyte, a small amount of H in the electrolyte solution at high temperature (55°C to 65°C) 2 O reacts with lithium salt to generate HF, and HF reacts with LiNi 0.5 mn 1.5 o 4 A reaction occurs, resulting in Mn 2+ dissolved, and LiNi 0.5 mn 1.5 o 4 It also has the effect of catalyzing the decomposition of electrolyte, which aggravates the decline of battery performance, so that the electrolyte on the surface of the electrode is continuously oxidized and decomposed and deposited on the surface of the electrode, which will hinder the deintercalation of lithium ions and lead to the cycle of the positive electrode material of the battery Poor performance and capacity attenuation limit its commercial application

[0004] In the prior art, for lithium nickel manganese oxide (LiNi 0.5 mn 1.5 o 4 ) The doping modification of the material is to make the doping material in LiNi 0.5 mn 1.5 o 4 The mixing stage of the material preparation process is added at the same time, so that the prepared doped lithium nickel manganese oxide material is a bulk doped material. Due to the bulk phase doping, the doped material and LiNi 0.5 mn 1.5 o 4 The materials are mixed in the solid state, so more doping materials are consumed in the process of bulk doping, and the loss of doping materials is greater

The bulk phase doping process mainly refers to the doping material and lithium nickel manganese oxide (LiNi 0.5 mn 1.5 o 4 ) materials are directly mixed through solids, and then sintered at high temperature, which does not form good contact, so the amount of doping materials used is large, which affects the capacity of active materials.

[0005] The traditional lithium nickel manganese oxide (LiNi 0.5 mn 1.5 o 4 ) material coating modification aims to reduce lithium nickel manganese oxide (LiNi 0.5 mn 1.5 o 4 ) material as the positive electrode material, its direct contact area with the electrolyte, thereby inhibiting the occurrence of side reactions, which is characterized in that the coating material (such as metal oxide) is only wrapped in lithium nickel manganese oxide (LiNi 0.5 mn 1.5 o 4 ) The surface of the material particles may affect the battery's lithium deintercalation and reduce the discharge capacity of the positive electrode material

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