Preparation method of polyvinyl acetal based solid electrolyte

A polyvinyl acetal, solid electrolyte technology, used in circuits, electrical components, secondary batteries, etc., can solve the problem of reduced tensile strength of solid electrolytes, reduced flexibility of polymer segments, and difficult to maintain electrical conductivity. Improvement and other issues, to achieve the effects of excellent macro and micro morphology, improved purity, and increased quantity

Active Publication Date: 2017-05-31
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since the proportion of hydroxyl groups in polyvinyl acetal, including polyvinyl formal and its homologues, is as low as ≤11%, the concentration of lithium ions complexed in the system through grafting reaction is low, so the conductivity of the system is difficult to continue. promote
Moreover, some precipitate clusters with a diameter of about 3 μm are diffusely distributed on the surface of the synthesized solid electrolyte, which leads to an increase in the crystallinity of the system and a decrease in the flexibility of the polymer chain segment, which in turn reduces the conductivity of the system, and the large precipitate particles cause The tensile strength of the solid electrolyte decreases

Method used

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  • Preparation method of polyvinyl acetal based solid electrolyte
  • Preparation method of polyvinyl acetal based solid electrolyte
  • Preparation method of polyvinyl acetal based solid electrolyte

Examples

Experimental program
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Effect test

Embodiment 1

[0028] (1) Take 0.8353g polyvinyl formal (molecular weight is 60000-80000, alcoholysis degree is 79%) and dissolve it in 5.5464g dimethyl sulfoxide, wherein the mass ratio of polyvinyl acetal to organic solvent is 1: 6.64, fully stir to dissolve completely, and prepare a homogeneous solution. Add 0.0284g of boric acid to the above solution (the molar ratio of hydroxyl group to boron atom is 2:1), stir magnetically at 70°C for 5 hours, then add 0.0187g of lithium carbonate and 0.0114g of oxalic acid (boron atom: lithium atom: oxalic acid) The molar ratio is 2:1:2). The water bath was stirred at 90°C for 24 hours, and finally cooled to room temperature to prepare solution system 1;

[0029] (2) Dissolve 0.0500g polyvinyl alcohol (molecular weight is 105000, alcoholysis degree is 98%-99%, pH value is 5-7) in 0.3322g dimethyl sulfoxide, wherein the mass ratio of polyvinyl alcohol to organic solvent The ratio was 1:6.64, and it was fully dissolved by stirring to obtain a homogene...

Embodiment 2

[0041] (1) Dissolve 0.8353g polyvinyl formal (molecular weight 60000-80000, alcoholysis degree 79%) in 8.5353g N,N-dimethylformamide, wherein the mass of polyvinyl acetal and organic solvent The ratio was 1:10, and the mixture was fully dissolved by stirring to obtain a homogeneous solution. Add 0.0321 g of boric acid to the above solution (wherein the molar ratio of hydroxyl and boron atoms is 2:1), stir magnetically at 70°C for 5 hours, then add 0.0122 g of lithium hydroxide and 0.0639 g of oxalic acid (boron atom: lithium atom: The molar ratio of oxalic acid is 2:1:2). The water bath was stirred at 90°C for 24 hours, and finally cooled to room temperature to prepare solution system 1;

[0042] (2) The solution system prepared in step (1) was washed three times with deionized water, suction filtered, and then vacuum-dried at 100 ° C for 14 hours to remove water to obtain a solid product; there is no preparation of solution system 2 here, that is, according to claim 1 In th...

Embodiment 3

[0047] (1) Dissolve 0.8597g of polyvinyl butyral (molecular weight is about 70000) in 6.5939g of N,N-dimethylformamide, wherein the mass ratio of polyvinyl acetal to organic solvent is 1: 7.67, Stir well to dissolve completely, and prepare a homogeneous solution. In the above solution, 0.0124g of boric acid (equivalent to a molar ratio of hydroxyl and boron atoms of 5:1) was stirred magnetically at 60 °C for 5 hours, and then 0.0044g of methyllithium and 0.0180g of oxalic acid (boron atom: lithium atom: oxalic acid) were added. The molar ratio is 2:1:2). The water bath was stirred at 90°C for 24 hours, and finally cooled to room temperature to prepare solution system 1;

[0048] (2) Dissolve 0.1174g polyvinyl alcohol (molecular weight is 110000, alcoholysis degree is 85%-88%, pH value is 6-8)) and dissolve in 1.4088g N,N-dimethylformamide, among which polyvinyl alcohol The mass ratio to the organic solvent is 1:12, and it is fully dissolved by stirring to obtain a homogeneou...

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Abstract

The invention provides a preparation method of a polyvinyl acetal solid electrolyte. The preparation method comprises the steps of respectively reacting polyvinyl formal or a homologue of polyvinyl formal and polyvinyl alcohol with boric acid, oxalic acid and lithium salt in an organic solvent system step by step, performing mixing in proportion, performing washing, suction filtration and drying, synthesizing high-purity polymer lithium salt with a lithium mono(oxalato) borate structure grafted on a polymer molecular chain, dissolving the high-purity polymer lithium salt in an organic solvent to form a settled solution, and finally preparing the solid electrolyte. The solid electrolyte prepared by the method has lithium ion migration number approximate to 1, excellent room-temperature conductivity greater than or equal to 10<-4>S / cm, a wide electrochemical stability window greater than or equal to 6V(vs.Li / Li<+>), outstanding thermal stability, high tensile strength greater than or equal to 35MPa, and excellent comprehensive performance for an all-solid battery system.

Description

technical field [0001] The invention belongs to the technical field of solid electrolyte preparation, in particular to a preparation method of a polyvinyl acetal-based solid electrolyte, which provides a solid electrolyte system with high ionic conductivity for energy conversion and storage devices with high specific energy and high safety. Background technique [0002] Solid electrolytes are an important type of electrolyte materials. Using solid electrolytes to assemble all-solid-state batteries is an effective method to solve the problems of poor safety and low energy density of lithium-ion batteries. However, traditional solid-state electrolytes and organic electrolyte systems are both double-ion conductors, that is, cations (such as Li + ) and anions both migrate. In this case, the lithium ion migration number is relatively low, only between 0.2 and 0.5, and some are even less than 0.1. During the charging process, anions are enriched near the positive electrode, while...

Claims

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Application Information

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IPC IPC(8): H01M10/0565
CPCH01M10/0565Y02E60/10
Inventor 连芳白丽娟张红男孙晓蒙
Owner UNIV OF SCI & TECH BEIJING
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