Composite positive electrode material, positive electrode sheet and all-solid lithium battery

A composite positive electrode material and lithium battery technology, which is applied in the direction of lithium batteries, battery electrodes, non-aqueous electrolyte batteries, etc., can solve the problem of small effective contact area between solid electrolyte and electrode materials, poor rate performance and cycle performance, and low discharge specific capacity, etc. problem, to achieve the effect of improving rate performance and cycle stability, improving utilization rate, and reducing lithium impurity content

Active Publication Date: 2020-10-02
NINGDE AMPEREX TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The interdiffusion of elements at the interface between the solid electrolyte and the electrode material will form a space charge layer, resulting in high impedance at the interface between the electrode material and the solid electrolyte; the effective contact area between the solid electrolyte and the electrode material is small; there are impurities and defects on the surface of the electrode material itself , leading to electrode materials (such as commonly used LiCoO 2 , NCM or NCA) for the first time in all-solid-state lithium batteries with low Coulombic efficiency, low discharge specific capacity, poor rate performance and cycle performance

Method used

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  • Composite positive electrode material, positive electrode sheet and all-solid lithium battery
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  • Composite positive electrode material, positive electrode sheet and all-solid lithium battery

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preparation example Construction

[0024] According to the preparation method of the composite positive electrode material of the second aspect of the present application, it is used to prepare the composite positive electrode material of the first aspect of the present application, comprising the steps of: making the positive electrode material Li n Ni x co y m z N m o 2Disperse into the ball milling medium and use a planetary ball mill for ball milling to break the positive electrode material into primary particles, and then anneal in an oxygen atmosphere to obtain the core material; dissolve soluble lithium salts, cobalt salts, and compounds containing Ma A large amount of complexing agent is continuously stirred to form a uniform mixed solution, and the pH value and temperature are adjusted to form a uniform sol; the obtained core material is added to the sol, continuously stirred until uniform, dried, and the shell material is coated On the surface of the core material, heat treatment is then performed...

Embodiment 1

[0042] Spherical cathode material LiNi 0.5 co 0.2 mn 0.3 o 2 Add it into a planetary ball mill for ball milling to break it into primary particles, the ball milling speed is 400rpm, the ball milling time is 8h, the ball-to-material ratio is 3:1, the ball milling medium is ethanol, and it is dried after ball milling, and then placed in an oxygen atmosphere at 850°C Anneal for 10 hours to obtain the core material; accurately weigh lithium acetate, cobalt acetate and aluminum isopropoxide according to the molar ratio Li:Co:Al=1:0.97:0.03, dissolve them in ethanol, and add a certain amount of citric acid as a complexing agent Adjust the pH value of the agent and continue to stir to form a uniform mixed solution, and continue to stir at 80°C to make the shell material form a uniform sol.

[0043] The core material is added to the sol, placed in a water bath at 80°C and continuously stirred to form a gel, then vacuum-dried, and then heat-treated. The heat treatment process is 900...

Embodiment 2

[0046] The preparation method of the composite positive electrode material is the same as in Example 1, the difference is that the LiNi 0.5 co 0.2 mn 0.3 o 2 replace with Li 0.95 Ni 0.5 co 0.2 mn 0.3 o 2 According to the method of Example 1, an all-solid-state lithium battery was constructed to evaluate the electrochemical performance of the composite cathode material. The all-solid-state lithium battery was disassembled, and the cycled composite positive electrode material was tested, and the concentration of element Ma on the surface of the shell was greater than the concentration of element Ma at the interface between the shell and the core.

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Abstract

The invention provides a composite positive electrode material, a positive plate and an all-solid-state lithium battery. The composite positive electrode material comprises a core and a shell, whereinthe shell covers the surface of the core. The general formula of the core is Li<n>Ni<x>Co<y>M<z>N<m>O<2>, wherein n is no less than 0.95 and no more than 1.05; x is no less than 0.5 and less than 1;y is more than 0 and no more than 0.4; z is more than 0 and no more than 0.4; m is no less than 0 and no more than 0.05; x, y, z and m sum to 1; M is at least one selected from the group consisting ofMn and Al; and N is at least one selected from the group consisting of Mg, Ti, Zr, Nb, Y, Cr, V, Ge and Mo. The general formula of the shell has a general formula of Li<alpha>Co<1-beta>Ma<beta>O<2>,wherein alpha is no less than 1 and no more than 1.08; beta is no less than 0 and no more than 0.1; and Ma is at least one selected from the group consisting of Al, Mg, Nb, Ti, Zr and V. The core is aprimary particle. The composite positive electrode material has the advantages of high initial coulombic efficiency, high specific discharge capacity, good rate performance, excellent cycle performance and low interface impedance of a solid electrolyte, and can improve the energy density and power density of the all-solid-state lithium battery.

Description

technical field [0001] The present application relates to the field of lithium batteries, in particular to a composite positive electrode material, a positive electrode sheet and an all-solid lithium battery. Background technique [0002] At present, the measures to solve the safety problems of traditional lithium-ion batteries mainly include: adding flame retardants to the electrolyte, using high-temperature resistant ceramic separators, surface modification of positive and negative electrode materials, battery structure design and BMS optimization, and phase change coating on the outer surface of the battery. Flame retardant materials and improved cooling systems, etc. These methods can improve the safety performance of existing lithium-ion batteries to a considerable extent, but cannot fundamentally guarantee the safety performance of large-capacity lithium-ion batteries. The all-solid-state lithium battery that replaces the traditional organic liquid electrolyte with an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/131H01M4/36H01M4/505H01M4/525H01M10/052
CPCH01M4/131H01M4/366H01M4/505H01M4/525H01M10/052Y02E60/10
Inventor 彭刚郎野刘凯徐磊敏
Owner NINGDE AMPEREX TECH
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