High-capacity lithium ion battery gradient cathode material and preparation method thereof

Abstract

The invention discloses a high-capacity lithium ion battery gradient cathode material and a preparation method of the material. The high-capacity lithium ion battery gradient cathode material contains a cobalt source substance, a lithium source material, a doping agent M and a cladding material, wherein the molar ratio of Li to Co is 0.95-1.2; the doping amount of the doping agent M is 0.01-10wt%, and the doping amount of the clad material is 0.01-20wt%. The high-capacity lithium ion battery gradient cathode material and the preparation method of the material solve the problems in the prior art; the high-capacity lithium ion battery gradient cathode material not only improves the structural stability of core material lithium cobalt oxide, but also improves the stability of shell material, and reduces the difference between resistance and discharge potential of the shell material and the core material so that the shell material and the core material reach a more consistent level on the aspect of Li+ deintercalation; secondly, the active substance is coated on the raw material, so that the complementary advantages between the core material lithium cobalt oxide and the shell material can be realized; furthermore, Co has continuous concentration change from the core material to the shell material, so that the cladding function is fully exerted, the material structure is stabilized, and the safety and the electrochemical performance of the material are improved.

Description

[0001] technical field [0002] The invention relates to the fields of energy storage materials and electrochemistry, in particular to a gradient cathode material for a high-capacity lithium-ion battery and a preparation method thereof. Background technique [0003] As a cathode material for lithium-ion batteries, lithium cobalt oxide has the advantages of high working voltage, high energy density, easy synthesis and fast charge and discharge, so it is widely used. However, due to the structural defects of lithium cobalt oxide itself, the following problems have been caused. When the charging cut-off voltage of lithium-ion batteries is higher than 4.2V, a large amount of Co in the lithium cobalt oxide structure 3+ will become Co 4+ ,Co 4+ The existence of will lead to the formation of oxygen vacancies in the lithium cobalt oxide crystal form, thereby weakening the binding force between the transition metal Co and oxygen, making Co 4+ Dissolved in the electrolyte, thereby...

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Problems solved by technology

Whether the first charge-discharge capacity, charge-discharge coulombic efficiency, cycle performance, or discharge plateau voltage of the synthesized gradient positive electrode material are higher than the homogeneous material synthesized from the precursor obtained by the ordinary co-precipitation method, the synthesis adopts the fractional co-precipitation method to prepare The process is relatively complicated, and it is difficult to promote it in practical applications; Zhenlei Huang of Tsinghua University et al. (Journal of Power Sources 202 (2012) 284-290), prepared spherical LiNixCo(1?2x)MnxO2 material, as the radius increases, the concentration of cobalt decreases, and the prepared material has superior rate performance, but the fact In fact, the gradient of the material has disappeared in the subsequent high-temperature roasting with lithium, and the cycle performance of the battery has deteriorated.

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