A kind of graphene-coated lithium nickel manganate cathode material and preparation method thereof

Abstract

The invention provides a graphene-coated lithium nickel manganate positive electrode material, comprising a core, a transition metal atomic layer and a graphene superimposed layer sequentially coated on the surface of the core, and the core is nickel-manganate Lithium cathode material. The preparation method of the graphene-coated lithium nickel manganate positive electrode material provided by the invention has simple and controllable process, avoids the introduction of other impurity elements, can be produced on a large scale, has low production cost, and the product has good cycle performance and rate performance.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a graphene-coated lithium nickel manganate positive electrode material and a preparation method thereof. Background technique [0002] The discharge voltage of the high-voltage lithium nickel manganate cathode material is 4.7V (vs.Li + / Li 0 ) and a discharge specific capacity of 147mAh / g, which has a higher power density compared with the existing commercial lithium-ion battery cathode materials, and is more suitable for the field of power lithium-ion batteries. However, there are still some problems with the lithium nickel manganate cathode material: 1) During the production process of the lithium nickel manganate cathode material, there will be a lot of residual alkali on the surface, which is prone to side reactions with the electrolyte, resulting in a decrease in the cycle performance of the battery; 2) The electronic conductivity of lithium nickel ma...

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Problems solved by technology

However, there are still some problems in the lithium nickel manganese oxide positive electrode material: 1) During the production process of the lithium nickel manganese oxide positive electrode material, there will be more residual alkali on the surface, which is prone to side reactions with the electrolyte, resulting in a decrease in the cycle performance of the battery; 2) The electronic conductivity of lithium nickel manganese oxide cathode material is poor, and the rate performance needs to be improved

The cross-linking of multiple carbon tubes will form a porous structure, resulting in an increase in the specific surface area of ​​the positive electrode material, thereby reducing the compaction density of the positive electrode material; the porous structure will also increase the liquid absorption of the electrolyte and increase the cost of the lithium-ion battery

[0011] Publication No. CN106941173A Chinese Patent, Publication No. CN103280569B, and Chinese Patent Publication No. CN102263239B all use the method of mixing solid-phase positive electrode materials and liquid-phase graphene-based materials. This method makes graphene-based materials adsorb On the surface of the positive electrode material, since the graphene-based material has the physical characteristics of spontaneous wrinkling, there is a large interface resistance between the graphene-based material and the positive electrode material, resulting in a lower rate performance of the graphene-coated lithium nickel manganese oxide composite material. Difference

The carbon nanotubes described in the Chinese patent with the publication number CN107689449A grow vertically on the surface of the lithium-ion positive electrode material. This method increases the specific surface area of ​​the positive electrode material, improves the liquid absorption of the battery pole piece electrolyte, and reduces the weight of the pole piece. Compaction density; at the same time, more Ni elements are introduced into the positive electrode material, which is easy to produce mixed arrangement of Li and Ni elements in the material, resulting in a decrease in the cycle performance of the composite material

Moreover, these preparation methods all have the disadvantages of complex process, low yield and high production cost.

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