CN1049908C - High molecular solid electrolyte and preparing process thereof - Google Patents

Abstract

A polymer solid electrolyte and a preparation method thereof, which are characterized in that poly(methyl methacrylate-methacrylic acid) copolymer and polyethylene oxide are respectively dissolved in a water/ethanol mixed solvent, and polyoxidation is inhibited by hydrogen bond recombination. The crystallization of ethylene, the plasticizer has good compatibility with polyethylene oxide, and has a strong dissociation ability for alkali metal salts, which can increase the movement of polyethylene oxide chain segments, improve the ionic conductivity of the solid electrolyte, and obtain room temperature conductivity in the range of (1.0～8.3)×10 ^-5 scm ^-1 , open circuit voltage 2.5～3.0V, good film formation and mechanical properties, good stability to time and temperature, can be used in solid-state high-energy batteries, electrochromic display materials, capacitors , sensors, etc.

Description

Polymer solid electrolyte and preparation method thereof

The invention relates to a polymer solid electrolyte and a preparation method thereof. The material has the advantages of good viscoelasticity and the like, and is an ideal electrolyte material for an all-solid-state high-energy lithium battery.

Because the polymer solid electrolyte has good film-forming properties, easy processing, and good viscoelasticity, it can adapt to changes in electrode materials during battery charging and discharging, and has good chemical stability. It overcomes the leakage of liquid electrolyte batteries and the relationship between inorganic solid electrolytes and batteries. Poor electrode contact, poor impact resistance, and difficult processing. Electrolytes with room temperature conductivity above 10 ^-5 Scm ^-1 are practical, and polymer solid electrolytes are considered to be ideal electrolyte materials for the development of all-solid-state high-energy lithium batteries. Countries around the world have invested a lot of manpower and material resources in competing research. Among the base materials of polymer solid electrolytes, polyethylene oxide (PEO) is the most researched. Studies have shown that the ionic conduction of polymer solid electrolytes based on PEO is realized through the segmental movement of polyethylene oxide, and the ionic conductivity mainly occurs in the amorphous region of PEO Wleczorek, W. et al, Solid State Ionics, 28-30, 1014 (1988), the easy crystallization nature of PEO limits the improvement of the material conductivity. In recent years, countries have explored how to reduce the crystallinity of PEO in the research of PEO solid electrolytes, such as reducing the molecular weight and introducing components with low glass transition temperatures. Wright, PV et al Polymer, 23, 681 (1982), grafting, and large Monomer copolymerization, crosslinking, interpenetrating network (IPN), etc., Xia, DWSmid, J., J. Polym. Sci Polym. Lott., 22, 617 (1984). Sun Fang, Feng Linxian, Yang Shilin, Applied Chemistry, 4, 40(1987), Fish, D., Smid, J.et al, Markromol, Chem., Rapid Commun., 6,761(1985).Chiang, CKet al Polym . Commun., 28, 34 (1987). However, these methods are difficult to prepare polymer solid electrolytes with good electrical conductivity, film-forming properties and mechanical properties. The polymer solid electrolytes reported in relevant literature generally work at high temperatures of 100-140°C, which is far from practical application. large distance.

The object of the present invention is to provide a kind of polymer solid electrolyte and preparation method thereof in view of the deficiencies in the prior art, it is characterized in that the crystallization of PEO is suppressed by hydrogen bond recombination, the compatibility of plasticizer and PEO is good, to alkali The metal salt has a strong dissociation ability, which can increase the movement of the PEO chain segment and improve the ionic conductivity of the solid electrolyte. The room temperature conductivity is (1.0～8.3)×10 ^-5 Scm ^-1 , and the open circuit voltage is 2.5～3.0V. It is a polymer solid electrolyte with good film-forming and mechanical properties and practical value.

The polymer solid electrolyte provided by the present invention and its preparation method, its starting material formulation components (by weight) are:

(Methyl methacrylate-methacrylic acid) copolymer [P(MMA-MAA)] (MAA content 0.5-0.85mol fraction) 30-60 parts

Polyethylene oxide ( M _η 10 ⁶ ～10 ⁷ ) 15～30 parts

Alkali metal salt (available LiClO ₄ , NaClO ₄ , LiSCN, KSCN, NaSCN and LiCF ₃ SO ₃ ) 5-25 parts

Polyethylene oxide (M _η 200～6000) 5～25 parts

solvent

Water/ethanol (1:1～5) 60～80 parts

Ethanol/1.4 dioxane (1:1~4) 60~80 parts

Weigh respectively according to the aforementioned formula, first dissolve methyl methacrylate (MMA)-methacrylic acid (MAA) copolymer and polyethylene oxide (PEO) respectively in water/ethanol mixed solvent, pour the two solutions into a After mixing evenly in the container, let it stand for 2 hours to obtain a composite precipitate, remove the solvent, and vacuum-dry the composite precipitate at a temperature of 60-70°C. Then dissolve the complex in ethanol/1.4 dioxane mixed solvent, add alkali metal salt and plasticizer, form a film after mixing evenly, slowly evaporate to remove the solvent, and obtain the above-mentioned polymer solid electrolyte material.

The polymer solid electrolyte material is colorless, transparent, and has good mechanical and mechanical properties. The conductivity at room temperature is 1.0-8.3×10 ^-5 cm ^-1 , and the open-circuit voltage is 2.5-3.0 volts.

The present invention has the following advantages:

1. The use of hydrogen bond recombination can effectively inhibit the crystallization of PEO and improve the mechanical strength of the system. At the same time, adding a plasticizer can further increase the mobility of the PEO chain segment, thereby improving the conductivity of the polymer solid electrolyte.

2. The solid electrolyte material prepared by the method has good stability to time and temperature, and can be used in all-solid-state high-energy lithium batteries, electrochromic display materials of all-solid-phase systems, capacitors, sensors, and antistatic materials.

3. The process is simple, the cost is low, the product quality is high, the applicability is strong, it is easy to popularize and apply, and has remarkable economic and social benefits.

Example 1

2.67 grams of P(MMA-MAA) copolymer and 1.32 grams of PEO were respectively dissolved in water/ethanol (1:1～5) mixed solvent, the two solutions were poured into a container and mixed evenly, and left to stand for 2 hours to obtain The complex was precipitated, the solvent was removed, and the complex was vacuum-dried at 60-70°C, then 2.33 g of the complex was dissolved in ethanol/1.4 dioxane (1:1-4) mixed solvent, and 0.45 g of _LiClO4 was added, Plasticizer polyethylene oxide (M _η 200 ~ 6000) 0.65 grams, mixed evenly to form a film, slowly evaporated to remove the solvent, to obtain 3.4 grams of polymer solid electrolyte product, 25 ° C, the measured conductivity was 3.62 × 10 ^-5 Scm ^-1 .

Example 2

The composite was prepared according to the method of Example 1, and then 2.33 grams of the composite was dissolved in ethanol/1.4 dioxane mixed solvent, 0.9 grams of LiClO ₄ and 1.1 grams of plasticizer polyoxyethylene were added, and the film was formed after mixing evenly. Obtain 4.3 grams of polymer solid electrolyte. At 25°C, the measured electrical conductivity was 8.31×10 ^-5 scm ^-1 .

Example 3

Prepare the composite according to the method of Example 1, then dissolve 2.33 grams of the composite in the ethanol/1.4 dioxane mixed solution, add 0.21 grams of KSCN, 1.05 grams of polyethylene oxide and mix evenly to form a film to obtain a polymer solid electrolyte 3.5 grams.

Example 4

The composite was prepared according to the method of Example 1, and then 2.33 g of the composite was dissolved in ethanol/1.4 dioxane, and 0.27 g of NaClO ₄ and 1.0 g of polyethylene oxide were added to form a film after mixing evenly to obtain a polymer solid electrolyte 3.6 gram.

Example 5

Prepare the composite according to the method of Example 1, then dissolve 2.33 grams of the composite in ethanol/1.4 dioxane mixed solvent, add 0.17 grams of NaSCN, 0.85 grams of polyethylene oxide and mix uniformly to form a film to obtain a polymer solid electrolyte 3.3 grams.

Example 6

Mix the reactants of 5 grams of NaOH and 4 grams of V ₂ O ₅ with the solid electrolyte product obtained in Example 1 to form a film, then make a composite cathode, use lithium as the anode, and assemble it into a button-type electrode with a diameter of 2 mm. battery, the measured open circuit voltage was 3.0 volts,

Claims (3)

1. A polymer solid electrolyte, characterized in that the formula component (by weight) of the starting material used in the polymer solid electrolyte is: Methyl methacrylate-methacrylic acid copolymer methacrylic acid content 0.5-0.85mol fraction 30-60 parts Polyoxyethylene M _η 10 ⁶ ～10 ⁷ 15～30 parts Alkali metal salt 5-25 parts Polyoxyethylene M _η 200～6000 5～25 parts solvent Water/ethanol 1:1~5 60~80 parts Ethanol/1.4 dioxane 1:1~4 60~80 parts 2. According to the polymer solid electrolyte according to claim 1, it is characterized in that the alkali metal salt of the polymer solid electrolyte is lithium perchlorate, lithium thiocyanate, lithium perfluoromethanesulfonate, potassium thiocyanate, high Sodium chlorate and sodium thiocyanate. 3. according to the preparation method of the described polymer solid electrolyte of claim 1, it is characterized in that the manufacture method of this polymer solid electrolyte is to weigh respectively by aforesaid formula, first methyl methacrylate and methacrylic acid copolymer and poly Ethylene oxide was dissolved in water/ethanol mixed solvent respectively, and the two solutions were poured into a container, mixed evenly, and then left to stand for 2 hours to obtain a composite precipitate. The solvent was removed, and the composite precipitate was vacuum-dried at a temperature of 60-70°C. Then dissolve the complex in ethanol/1.4 dioxane mixed solvent, add alkali metal salt and plasticizer, mix uniformly, form a film, slowly evaporate to remove the solvent, and obtain the above-mentioned polymer solid electrolyte material.