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Preparation method of high-efficiency negative active material for lithium ion secondary battery

A negative electrode active material and lithium-ion battery technology, applied in the direction of secondary batteries, battery electrodes, circuits, etc., can solve the problems of not being suitable for large-scale production, not effectively improving the first effect, affecting Coulombic efficiency, etc., and achieving excellent electrochemical performance Effects of cycle stability, inhibition of SEI film formation, and improvement of Coulombic efficiency

Active Publication Date: 2019-05-21
NANKAI UNIV
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Problems solved by technology

[0005] CN107293701A discloses a lithium ion battery negative electrode active material and its preparation method, negative electrode and lithium ion battery containing the negative electrode, but in the preparation process, adding organic solvent and negative electrode active material lithium-silicon alloy to make slurry may cause lithium In the case of silicon alloy and solvent reaction, the active material is lost, the safety is not high, and it is not suitable for industrial large-scale production
[0006] CN108063222A discloses a preparation method of lithium-ion battery negative electrode material and lithium-ion battery. Silicon is deposited on the lithium metal layer by magnetron sputtering, and then the lithium metal layer deposited with silicon is heated and melted to obtain the lithium-ion battery negative electrode material. During the preparation process, lithium-silicon alloy-silicon layer may be obtained, or silicon is oxidized by oxygen in the air during the preparation process to obtain an uncertain mixed coating such as lithium-silicon alloy-silicon dioxide layer. The oxide-containing negative electrode material will inevitably affect the material. Coulombic efficiency in the first week, and the preparation process is complex and requires high equipment, high cost, and poor industrial operability
However, the final product of this invention is a silicon-based material, which does not play the role of pre-lithiation, and does not effectively improve the first effect.
[0008] CN106799497A discloses a production process of nano-lithium-silicon alloy powder. Waste gas will be produced in the process of preparing nano-lithium-silicon alloy by smelting method, which will pollute the environment

Method used

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  • Preparation method of high-efficiency negative active material for lithium ion secondary battery
  • Preparation method of high-efficiency negative active material for lithium ion secondary battery
  • Preparation method of high-efficiency negative active material for lithium ion secondary battery

Examples

Experimental program
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Effect test

Embodiment 1

[0043] Lithium-ion battery of the present invention can be prepared by the following method:

[0044] (1) Li 4.4 Preparation of Si:

[0045] The pre-milled silicon powder and shredded lithium flakes were mixed and placed in a zirconia ball mill jar at a molar ratio of 1:4.4, and cyclohexane was added as a lubricant, and high-energy ball milled on a planetary ball mill at a speed of 450 rpm for 15 hours. (The ball used is made of stainless steel) The material ratio is 100:1 to obtain nano-scale Li 4.4 Si material.

[0046] (2) Preparation of silicon / graphite / carbon composite negative electrode material:

[0047] (1) Put the above pre-milled silicon powder and pre-milled graphite in a ceramic ball mill tank according to the mass ratio of 25:55, and mix them in a high-energy ball mill on a planetary ball mill at a speed of 400 rpm for 5 hours. The material ratio of the balls (the balls used are made of ceramic materials) is 10:1, get silicon / graphite composite material.

[0...

Embodiment 2

[0062] (1) Li 4.4 Preparation of Si:

[0063] The silicon powder after pre-ball milling and the shredded lithium flakes are mixed in a zirconia ball mill jar according to a molar ratio of 1:5.2, and n-hexane is added as a lubricant, and high-energy ball milling is carried out on a planetary ball mill at a speed of 400rpm for 10h, and the balls ( The ball used is made of stainless steel) with a material ratio of 80:1 to obtain nanoscale Li 4.4 Si material.

[0064] Li prepared above 4.4 XRD patterns of Si and figure 2 similar.

[0065] (2) Preparation of silicon / graphite / carbon composite negative electrode material:

[0066] (1) Put the above pre-milled silicon powder and pre-milled graphite in a ceramic ball mill tank according to the mass ratio of 30:50, and mix them in a high-energy ball mill on a planetary ball mill at a speed of 450rpm for 10 hours. The material ratio of the balls (the balls used are ceramic materials) is 20:1, to obtain a silicon / graphite composite...

Embodiment 3

[0078] (1) Li 4.4 Preparation of Si:

[0079] The silicon powder after the pre-ball milling and the shredded lithium flakes are mixed and placed in a zirconia ball mill jar according to a molar ratio of 1:5.8, and toluene is added as a lubricant, and high-energy ball milling is performed on a planetary ball mill at a speed of 500rpm for 20h, and the balls (used The ball is made of stainless steel) The material ratio is 120:1, and the nano-scale Li 4.4 Si material.

[0080] Li prepared above 4.4 XRD patterns of Si and figure 2 similar.

[0081] (2) Preparation of silicon / graphite / carbon composite negative electrode material:

[0082] (1) Put the above pre-milled silicon powder and pre-milled graphite in a ceramic ball mill tank at a mass ratio of 15:75, and mix them with a high-energy ball mill on a planetary ball mill at a speed of 350rpm for 5 hours. The material ratio of the balls (the balls used are ceramic materials) is 15:1, to obtain silicon / graphite composites. ...

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Abstract

The invention relates to a preparation method of a high-efficiency negative active material for a lithium ion secondary battery. Lithium-silicon alloys Li4.4Si, Li3.25Si and Li1.71Si are prepared by high-energy ball milling. The preparation method is simple, pollution-free and high in safety. At the same time, a suitable solvent is added in the high-energy ball milling to serve as a lubricant, thereby greatly improving the efficiency of an alloying reaction. A composite material is prepared from a lithium-silicon alloy together with pre-ball-milling silicon powder, graphite and carbon has a unique structure, which inhibits the volume expansion of materials during charging and discharging. Moreover, LixSi has high capacity and higher conductivity than pure silicon, and contains lithium, which can inhibit the formation of an SEI film in the first week and improve the first week coulombic efficiency of materials. Secondly, the experimental results of the invention show that the synthesized LixSi can be transformed into amorphous silicon after lithium removal, thereby effectively alleviating the volume change during charging and discharging, and exhibiting cycle performance far exceeding that of crystalline silicon. The high-efficiency negative active material is environmentally friendly, simple and feasible in preparation method and instrument and equipment, high in safety, and suitable for industrial production.

Description

technical field [0001] The invention relates to a preparation method of a high first-efficiency lithium ion secondary battery negative electrode active material. Background technique [0002] As a sustainable energy storage device, lithium-ion secondary batteries have been widely used in smartphones, portable electronic devices, hybrid electric vehicles, and large energy storage devices due to their unique characteristics. However, due to the high irreversible capacity in the first week, low theoretical capacity (372mAh / g), and poor safety during the lithium intercalation process, commercial carbon anode materials have been difficult to meet the requirements of high-energy power sources. [0003] Because of its high specific capacity (4200mAh / g), low voltage platform, and good safety performance, silicon-based anode materials are ideal substitutes for carbon-based anode materials, and have attracted widespread attention. Follow and study. However, the conductivity of eleme...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/134H01M4/1395H01M4/36H01M4/38H01M4/587H01M10/0525C22C24/00
CPCY02E60/10
Inventor 杨化滨李小花
Owner NANKAI UNIV
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