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Positive electrode composite material and preparation method thereof, positive electrode and lithium battery

A technology of composite materials and positive electrode materials, which is applied in the field of positive electrodes and lithium batteries, positive electrode composite materials and their preparation, can solve problems affecting the structural stability of materials, hindering the development of ternary materials, battery capacity attenuation, etc., to improve cycle stability , Improve structural stability and thermal stability, high thermal safety effect

Pending Publication Date: 2021-11-26
TSINGHUA UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Theoretically, the lithium ions in the ternary material can be completely extracted, and the reversible specific capacity is as high as 274mAh g -1 , but in practical applications, when the cut-off voltage is increased and the reversible deintercalation of lithium ions exceeds 0.5 units, the octahedron between transition metal ions and oxygen ions becomes unstable and transforms into a spinel phase, which causes internal changes in the crystal affect the structural stability of the material
In addition, the side reaction between the electrode material and the electrolyte is intensified under high voltage, causing the battery capacity to decay rapidly. These problems are important reasons hindering the development of ternary materials.

Method used

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  • Positive electrode composite material and preparation method thereof, positive electrode and lithium battery
  • Positive electrode composite material and preparation method thereof, positive electrode and lithium battery
  • Positive electrode composite material and preparation method thereof, positive electrode and lithium battery

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preparation example Construction

[0047] In one aspect of the present invention, there is also provided a method for preparing the above-mentioned positive electrode composite material, which includes the following steps:

[0048] The lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane are mixed with the ternary positive electrode material in solid state, so that the lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane cover the ternary positive electrode material.

[0049] Due to the strong electrostatic adsorption between lithium iron phosphate nanosheets and ternary cathode materials, lithium iron phosphate nanosheets can be better coated with ternary cathode materials only through a simple solid-phase mixing process, thereby avoiding the The side reaction between the ternary cathode material and the electrolyte under high voltage is eliminated, and the cycle stability of the electrode material is improved.

[0050] In some embodiments, ...

Embodiment 1

[0072] 1) Preparation of lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane

[0073] LiOH, H with a molar ratio of 3:1:1 3 PO 4 and FeSO 4 Disperse in ethylene glycol and stir to obtain a mixed suspension. The mixed suspension was added to the reactor, and a hydrothermal reaction was carried out at 180 °C for 10 h to obtain a lithium iron phosphate precursor, which was then compounded with glucose and polyvinyl alcohol and sintered at 650 °C in a nitrogen atmosphere for 3 h to obtain Lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane.

[0074] 2) 0.97 LiNi 0.6 co 0.2 mn 0.2 o 2 @0.03 LiFePO 4 preparation of

[0075] Take 3wt% of the above-mentioned lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane and 97wt% of powdered LiNi 0.6 co 0.2 mn 0.2 o 2 Mix for 12 hours in a three-dimensional mixer without adding balls to prepare 0.97LiNi 0.6 co 0.2 mn 0.2 o ...

Embodiment 2

[0087] The preparation method of this embodiment 2 is basically the same as that of embodiment 1, the difference is: LiFePO 4 The mass percentage content is 5%. Specific steps are as follows:

[0088] 1) Preparation of lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane

[0089] LiOH, H with a molar ratio of 3:1:1 3 PO 4 and FeSO 4 Disperse in ethylene glycol and stir to obtain a mixed suspension. The mixed suspension was added to the reactor, and a hydrothermal reaction was carried out at 180 °C for 10 h to obtain a lithium iron phosphate precursor, which was then compounded with glucose and polyvinyl alcohol and sintered at 650 °C in a nitrogen atmosphere for 3 h to obtain Lithium iron phosphate nanosheets grown along the preferred orientation of the ac plane.

[0090] 2) 0.95 LiNi 0.6 co 0.2 mn 0.2 o 2 @0.05 LiFePO 4 preparation of

[0091] Take 5wt% of the above-mentioned lithium iron phosphate nanosheets grown along the pref...

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Abstract

The invention relates to the technical field of lithium batteries, in particular to a positive electrode composite material and a preparation method thereof, a positive electrode and a lithium battery. The positive electrode composite material comprises a lithium iron phosphate nanosheet growing along an ac surface in a preferred orientation manner and a ternary positive electrode material coated with the lithium iron phosphate nanosheet. The positive electrode material has high specific energy, high chemical stability and thermal safety. The invention further provides a preparation method of the positive electrode composite material, a positive electrode comprising the positive electrode composite material, and a lithium battery.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a positive electrode composite material, a preparation method thereof, a positive electrode and a lithium battery. Background technique [0002] As an important new type of green energy, lithium-ion batteries have been widely used in people's lives. Among them, the ternary layered cathode material of lithium ion battery is LiNi 1-x-y co x mn y o 2 , compared to single-component layered materials such as LiCoO 2 , LiNiO 2 and LiMnO 2 , has the advantages of low cost, large reversible specific capacity, and good cycle performance, and is one of the positive electrode materials with good application prospects. Theoretically, the lithium ions in the ternary material can be completely extracted, and the reversible specific capacity is as high as 274mAh g -1 , but in practical applications, when the cut-off voltage is increased and the reversible deintercalation of li...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/58H01M4/485H01M4/505H01M4/525H01M4/131H01M4/136H01M10/0525B82Y30/00B82Y40/00
CPCH01M4/366H01M4/5825H01M4/505H01M4/525H01M4/485H01M4/131H01M4/136H01M10/0525B82Y30/00B82Y40/00H01M2004/028H01M2004/021Y02E60/10
Inventor 何向明王莉胡乔
Owner TSINGHUA UNIV
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