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Composite nanofiber lithium battery diaphragm and preparation method thereof

A technology of composite nanofibers and lithium battery separators, applied in battery pack parts, separators/films/diaphragms/spacers, circuits, etc. To solve problems such as poor mechanical properties, to achieve the effects of excellent mechanical properties, improved electrochemical properties, and improved mechanical properties

Active Publication Date: 2021-12-03
HENAN INST OF ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the commercialized separator materials are mainly polyolefin separator materials. Due to the poor wettability of the electrolyte, the polyolefin separator materials seriously affect the lithium ion in the electrolyte. It is not conducive to the charging and discharging of high current, and the thermal stability is relatively low. The diaphragm is prone to thermal shrinkage at high temperature and causes short circuit of the battery. The above problems limit the application of polyolefin diaphragms in high-power batteries. The physical coating method coats inorganic nanoparticles on the surface of the polyolefin separator to improve the performance of the separator, but the physical coating method has uneven coating, which makes the thickness of the separator difficult to control, resulting in a decrease in the ionic conductivity of the separator and coating adhesion. Insufficient force and easy to fall off

Method used

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  • Composite nanofiber lithium battery diaphragm and preparation method thereof
  • Composite nanofiber lithium battery diaphragm and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0028] Preparation of PAA spinning solution:

[0029] Synthesize polyimide acid (PAA) spinning solution with pyromellitic dianhydride (PMDA) and 4,4-diaminodiphenyl ether (ODA) as raw materials: first dry PMDA and ODA, then dissolve ODA In N,N-dimethylacetamide (DMAC) and 1-methyl-2-pyrrolidone (NMP) volume ratio is 4: 6 mixed solvent, add PMDA while stirring, preparation mass concentration is 30-36wt% PAA spinning solution, standby; wherein, the molar ratio of PMDA to ODA is 1:1.

[0030] Preparation of PAN spinning solution:

[0031] Adding the dried polyacrylonitrile (PAN) powder into N,N-dimethylformamide (DMF) to prepare a PAN spinning solution with a mass fraction of 15-25% for later use.

[0032] TiOSO 4 Solution preparation: TiOSO 4 2H 2 O powder was dissolved in deionized water to prepare 0.5-2mol / L TiOSO 4 solution, set aside.

Embodiment 2

[0034] A composite nanofiber lithium battery separator, which has a coaxial three-layer composite structure, from outside to inside: the outer layer is TiO 2 Nano layer, the middle layer is a polyacrylonitrile (PAN) pre-oxidized fiber layer, and the core layer is a polyimide (PI) fiber layer; the thickness of the diaphragm is 20 μm; its preparation method specifically includes the following steps:

[0035] (1) Preparation of PAN@PAA nanofibrous membrane with coaxial double-layer structure

[0036] Using the PAA spinning solution with a mass concentration of 30wt% as the core material and the PAN spinning solution with a mass concentration of 20wt% as the shell material, a coaxial double-layer structure PAN@PAA nanofiber membrane was prepared by coaxial electrospinning technology; The coaxial electrospinning process parameters are as follows: the voltage is 18kV, the receiving distance is 20cm, the flow rate of PAA spinning solution is 0.1mL / h, and the flow rate of PAN spinning...

Embodiment 3

[0042] A composite nanofiber lithium battery separator, which has a coaxial three-layer composite structure, from outside to inside: the outer layer is TiO 2 Nano layer, the middle layer is a polyacrylonitrile (PAN) pre-oxidized fiber layer, and the core layer is a polyimide (PI) fiber layer; the thickness of the diaphragm is 50 μm; its preparation method specifically includes the following steps:

[0043] (1) Preparation of PAN@PAA nanofibrous membrane with coaxial double-layer structure

[0044] Using the PAA spinning solution with a mass concentration of 36wt% as the core material and the PAN spinning solution with a mass concentration of 18wt% as the shell material, a coaxial double-layer structure PAN@PAA nanofiber membrane was prepared by coaxial electrospinning technology; The coaxial electrospinning process parameters are as follows: the voltage is 18kV, the receiving distance is 20cm, the flow rate of PAA spinning solution is 0.2mL / h, and the flow rate of PAN spinning...

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Abstract

The invention discloses a composite nanofiber lithium battery diaphragm which has a coaxial three-layer structure, the outer layer is a TiO2 nano layer, the middle layer is a polyacrylonitrile (PAN) pre-oxidized fiber layer, and the core layer is a polyimide (PI) fiber layer; the preparation method specifically comprises the following steps: by taking a PAA spinning solution as a core material and a PAN spinning solution as a shell material, preparing a PAN@PAA nanofiber membrane with a coaxial double-layer structure through coaxial electrostatic spinning; dipping the PAN@PAA nanofiber membrane in a TiOSO4 solution, taking out the PAN@PAA nanofiber membrane, and naturally airing the PAN@PAA nanofiber membrane to prepare a TiO (OH) 2 nanolayer@PAN@PAA nanofiber membrane; and carrying out heat treatment on the TiO (OH) 2 nano layer@PAN@PAA nano fiber membrane to obtain the coaxial three-layer structure TiO2@PAN pre-oxidized@PI composite nano fiber membrane. The composite diaphragm has excellent thermal stability, excellent mechanical performance, good electrochemical performance and battery cycle performance.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery materials, and in particular relates to a composite nanofiber lithium battery diaphragm and a preparation method thereof. Background technique [0002] Lithium-ion batteries, as an important energy storage device, have been widely studied in the field of new energy. As an important part of lithium-ion batteries, the separator is mainly used to block the positive and negative electrodes, prevent the short circuit from direct contact between the two electrodes, and prevent The electrons pass freely, allowing the ions in the battery electrolyte to pass freely; the separator determines the interface structure and internal resistance of the lithium-ion battery, which can directly affect the battery's capacity, charge-discharge cycle performance, service life and safety performance. [0003] At present, the commercial diaphragm material is mainly polyolefin diaphragm material. Due to the poo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/40H01M50/403H01M50/431H01M50/457
CPCH01M50/40H01M50/431H01M50/457H01M50/403Y02E60/10
Inventor 于宾马思思边立然黄海涛张显华刘传明
Owner HENAN INST OF ENG
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