High-nickel lithium ion positive electrode material and preparation method thereof

Abstract

The invention discloses a high-nickel lithium ion positive electrode material. The molecular formula is LiNi<x>Co<y>Mn<1-x-y-z>M<z>O2, wherein M is a doping element, the lithium ion positive electrodematerial is spherical secondary particle formed by gathering primary particle, and the structure of the lithium ion positive electrode material is a homogeneous-phase structure, a core-shell structure and a concentration gradient structure. The preparation method of the lithium ion positive electrode material comprises the steps of preparing a high-nickel positive electrode material precursor andpreparing the lithium ion secondary battery positive electrode. The precursor of the high-nickel positive electrode material is synthesized by a co-precipitation method, uniform mixing of elements can be facilitated, reaction can be more sufficient by adding the aging process, and morphology control is facilitated; and with the adoption of multi-element co-doping, the stability of a material crystal structure can be improved, the content of a Mn element is reduced, other doping elements are introduced, the lithium and nickel mixed arrangement degree of the high-nickel positive electrode material can be reduced, the orderliness of a layered material is ensured, the structure of the material is stabilized, the discharging specific capacity is improved, so that the energy density of the battery is improved.

Description

technical field [0001] The invention relates to a lithium-ion battery cathode material, in particular to a high-nickel lithium-ion battery cathode material and a preparation method thereof. Background technique [0002] At present, the power battery is still mainly lithium iron phosphate battery, but its specific energy is limited, and it will be difficult to meet the needs of passenger vehicles in terms of cruising range in the future. Therefore, the pursuit of high specific energy is an important research and development direction of lithium-ion power batteries. Due to the difference in the capacity of the positive and negative electrodes, the positive electrode material is often the bottleneck that affects the energy density of the battery. LiNixCO1-XO2 cathode material has the advantages of lithium cobaltate and lithium nickelate, high discharge specific capacity, good cycle performance, low cost and less environmental pollution, but due to the high nickel material is pr...

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Problems solved by technology

LiNixCO1-XO2 cathode material has the advantages of lithium cobaltate and lithium nickelate, high discharge specific capacity, good cycle performance, low cost and less environmental pollution, but due to the high nickel material is prone to cation mixing phenomenon, thus There will be defects such as poor thermal stability and low initial charge and discharge efficiency. At present, in order to solve this problem, it is often modified by doping and coating. Although the mixing phenomenon is improved to a certain extent and the stability of the structure is improved, but Since the doping or coating is an inactive substance, the specific capacity of the battery is reduced to a certain extent. In order to solve this problem, PCT patent WO2016155314A1 discloses a high energy density nickel-cobalt-based lithium-ion positive electrode material and its preparation The method is to dope LiNixCO1-XO2 to modify and stabilize the structure of the material, and then to coat the active material and use binary co-doping to solve the phenomenon of cation mixing to a certain extent, but its structural stability is still low. There is room for further improvement, and this method adopts the traditional solid-state sintering method, which is difficult to ensure the uniformity of the distribution of doping elements in the material, and uneven distribution will also lead to deterioration of the discharge specific capacity, thereby affecting the cycle performance of the battery

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