High-capacity lithium-rich cathode material and preparation method thereof

Abstract

The invention discloses a high-capacity lithium-rich cathode material and a preparation method thereof. The general formula of the lithium-rich cathode material is Li[Lid(NiaCobMncMx)]O2, wherein M is one or more than one elements selected from Cu, Mg, Al, Y, Bi, Ti and Sn, a is more than or equal to 0.17 and less than or equal to 0.21, b is more than or equal to 0.09 and less than 0.13, c is more than or equal to 0.54 and less than or equal to 0.58, d is more than or equal to 0.10 and less than or equal to 0.15, x is more than or equal to 0 and less than or equal to 0.05, and the sum of a, b, c, d and x is 1. The high-capacity lithium-rich cathode material disclosed by the invention has the advantages of high specific capacity and high initial efficiency; initial discharge capacity can be 273mAh/g and the initial efficiency is higher than 89% during charge-discharge of 2-4.6V; and the initial discharge capacity can be 293mAh/g and the initial efficiency is higher than 87% during charge-discharge of 2-4.8V.

Description

technical field [0001] The invention relates to a high-capacity lithium-rich cathode material and a preparation method thereof, belonging to the field of cathode materials for lithium ion batteries. Background technique [0002] The current commercial cathode material is LiCoO 2 、LiFePO 4 , LiMn 2 o 4 And the ternary cathode material [Li(NiCoMn)O 2 ], the specific capacities of these cathode materials are below 200mAh / g. With the continuous upgrading of electronic products and the marketization of electric vehicles, there is an urgent need for lithium-ion battery cathode materials with higher capacity. [0003] In recent years, a lithium-rich cathode material with a layered structure, xLi 2 MnO 3 ·(1-x)LiMO 2 aroused widespread concern. The cathode material is Li 2 MnO 3 with LiMO 2 The solid solution formed can also be written as Li[M x Li 1 / 3-2x / 3 mn 2 / 3-x / 3 ]O 2 . Since the lithium-rich cathode material is mainly manganese, relatively speaking, it is rich...

AI Technical Summary

Problems solved by technology

In the Chinese patent application publication CN 101694876A, the obtained positive electrode material has a specific capacity greater than 200mAh / g when charging and discharging between 2.5 and 4.6V. However, from the general formula of the lithium-rich manganese-based positive electrode material provided by it, it does not It cannot represent all lithium-rich positive electrode materials with high capacity. For example, for the case of M=Co, the application did not conduct in-depth research, did not provide relevant examples, and did not propose a preferred range for the content of each element

Furthermore, according to its attached image 3 , the platform of the discharge curve of the lithium-rich manganese-based cathode material is not very good, and the performance needs to be further improved

[0004] Although the current lithium-rich cathode materials have high specific capacity, their cycle stability and rate performance are poor.

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