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Low-porosity positive pole piece, preparation method thereof and application of low-porosity positive pole piece in solid-state lithium metal battery

A positive pole piece and porosity technology, which is applied in the field of battery pole piece and lithium metal battery manufacturing, to achieve low internal resistance, high utilization rate, and increase battery energy density.

Active Publication Date: 2020-06-12
INST OF PROCESS ENG CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, without exception, the above-mentioned inventions did not conduct in-depth discussions on the porosity of the pole piece, especially the positive pole piece. In CN201880009551.0, in view of the volume change of the Si negative electrode during the cycle, the inventor made an in-depth study on the porosity of the pole piece. did more research

Method used

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  • Low-porosity positive pole piece, preparation method thereof and application of low-porosity positive pole piece in solid-state lithium metal battery
  • Low-porosity positive pole piece, preparation method thereof and application of low-porosity positive pole piece in solid-state lithium metal battery
  • Low-porosity positive pole piece, preparation method thereof and application of low-porosity positive pole piece in solid-state lithium metal battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030]The electrode uses lithium cobaltate with a mass fraction of 80% of D50 of 5 μm and D90 of 8 μm as the active material, adding 5% of Super P, and the binder is composed of [8% PAALi + 0.2% nano-Al 2 o 3 +1% LGPS+1% LiFSI and 4.8% ionic liquid], the structure of the ionic liquid is as follows:

[0031]

[0032] Its preparation steps are as follows:

[0033] 1) In an environment with a dew point lower than -60°C, mix the above-mentioned adhesives evenly to obtain a viscous composite adhesive with room temperature conductivity > 10 -4 S / cm;

[0034] 2) Mix lithium cobaltate and Super P evenly with a dry powder mixer;

[0035] 3) Dry-mix the binder with the mixture obtained in 2), heat and mix the mixture evenly with the twin-screw, and then extrude onto the surface of the aluminum foil to complete double-sided coating;

[0036] 4) Roll the obtained pole piece to obtain a pole piece with a porosity of about 15% and a designed surface capacity of 1.5mAh / cm on one side ...

Embodiment 2

[0039] The active material is lithium iron phosphate with a D50 of 150nm, 3% Ketjen black is added as a conductive agent, the main body of the binder polymer is PEO with a number average molecular weight of 200,000, and the ionic liquid is Li(G3) with a mass fraction of 6.8%. TFSI, other ratios are the same as in Example 1, that is, active material: conductive agent: binder = 80:3:17.

[0040] The preparation steps of the electrode sheet are the same as in Example 1, but the current collector is made of nickel foam, and the sheet is made by one coating. The capacity behind the pole piece rolling is 3.2mAh / cm 2 (both sides), porosity 19%.

[0041] The LLZO solid electrolyte sheet with a thickness of 0.5mm was used to form a button battery with the above-mentioned positive electrode and lithium sheet, and its charge and discharge performance was tested at 50°C and 0.1C.

Embodiment 3

[0043] The positive electrode uses NCM622 single crystal with a D50 of 3 μm, 2% Ketjen Black + 3% carbon nanotubes as the conductive agent, and the binder consists of 8% PVDF-HFP + 0.5% LiBF 4 +0.5%LiBOB+0.2%LiPF 6 +4%PP13TFSI+0.3%SiO 2 +1.5% LLZO composition, that is, active material: conductive agent: binder = 80:5:15.

[0044] During the preparation process, add the components of the binder to the NMP in proportion, stir at room temperature for 5 hours, then add the dry powder and mix the active material and the conductive agent uniformly. The solid content of the system is controlled at 50% to 70%. Coated on aluminum foil with a rough surface in an environment below -40°C, coated on both sides, dried and then hot-pressed at 80°C to obtain a porosity of 18.7% and a capacity of about 2.2mAh / cm on one side 2 pole piece.

[0045] The LLZO solid electrolyte sheet with a thickness of 0.5mm was used to form a button battery with the above-mentioned positive electrode and lithi...

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Abstract

The invention relates to a preparation method of a low-porosity positive pole piece suitable for a solid-state battery and the solid-state lithium metal battery. The positive pole piece is composed ofan active material, a conductive agent, a binder (having lithium ion conduction capability) and a current collector, and is characterized in that the positive active material is primary particles orlarge single crystals, and the typical size of the positive active material is 50 nm to 30 [mu] m; the binder, the conductive agent and the current collector have a synergistic effect, so that the integrity of ions and electronic channels in the pole piece is guaranteed; and the porosity of the pole piece is less than 20%. The pole piece provides a transmission channel for ions and electrons, so that the pole piece is in good interface contact with solid electrolyte and is suitable for a solid-state lithium metal battery.

Description

technical field [0001] The invention relates to the technical field of manufacturing battery pole pieces and lithium metal batteries, in particular to a low-porosity positive pole piece, a preparation method thereof and its application in solid lithium metal batteries. Background technique [0002] With the development of economy and society, lithium-ion batteries have become one of the necessities of daily life, and their energy density, safety and cost have gradually become the most concerned hot issues of the whole society. [0003] Most current lithium-ion batteries use transition metal oxide positive electrodes, graphite negative electrodes, and liquid electrolytes. On the one hand, due to the low specific capacity of graphite, the battery energy density can hardly exceed the upper limit of 300Wh / kg; Sex is not guaranteed. [0004] Solid-state lithium metal batteries are the most effective way to solve the above problems. In recent years, research on solid-state elect...

Claims

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Application Information

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IPC IPC(8): H01M4/505H01M4/525H01M4/58H01M4/62H01M4/131H01M4/136H01M4/1391H01M4/1397H01M4/04H01M10/052H01M10/0585H01M10/0587
CPCH01M4/02H01M4/0419H01M4/043H01M4/131H01M4/136H01M4/1391H01M4/1397H01M4/505H01M4/525H01M4/5825H01M4/622H01M4/623H01M4/625H01M10/052H01M10/0585H01M10/0587H01M2004/021Y02E60/10Y02P70/50
Inventor 张兰潘科成张琪鹏巫湘坤张锁江
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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