阅读说明：本技术 一种聚碳酸酯基嵌段聚合物电解质制备及应用 (Preparation and application of polycarbonate-based block polymer electrolyte ) 是由 尉海军 林志远 郭现伟 于 2019-10-14 设计创作，主要内容包括：一种聚碳酸酯基嵌段聚合物电解质制备及应用,涉及锂离子电解质的领域。具体为碳酸乙烯亚乙酯、C＝C双键化合物、导电锂盐、多孔支撑材料、有机溶剂和引发剂制备嵌段聚合物电解质。该聚合物电解质的制备工艺简单、易控,具有优异的力学性能；厚度为10-500μm；离子电导率2×10<Sup>-4</Sup>S cm<Sup>-1</Sup>～5×10<Sup>-3</Sup>S cm<Sup>-1</Sup>(25℃),电化学窗口＞5V(vs.Li<Sup>+</Sup>/Li。(polycarbonate-based block polymer electrolyte preparation and application, relating to the field of lithium ion electrolytes, in particular to a block prepared from ethylene carbonate, a C ═ C double-bond compound, conductive lithium salt, a porous support material, an organic solvent and an initiatorA polymer electrolyte. The preparation process of the polymer electrolyte is simple and easy to control, and has excellent mechanical properties; the thickness is 10-500 μm; ion conductivity 2X 10 ‑4 S cm ‑1 ～5×10 ‑3 S cm ‑1 (25 ℃), electrochemical window > 5V (vs. Li) + /Li。)

The polycarbonate-based block polymer electrolytes are characterized in that the adopted raw materials comprise 5-80% by mass of ethylene carbonate, 5-80% by mass of a C-C double bond compound, 5-80% by mass of a conductive lithium salt, 5-80% by mass of an organic solvent and 0.5-5% by mass of an initiator or a catalyst, the polycarbonate-based block polymer electrolytes are subjected to graft polymerization by a chemical method to prepare the polycarbonate-based block polymer electrolytes, wherein the ethylene carbonate and the C-C double bond compound react to form a polymer;

the structure of the polymer in the polycarbonate-based block polymer electrolyte is shown as a general formula 1:

wherein the value of n is 1-50000; the value of m is 1-50000; r₁、R₂、R₃And R₄ kinds selected from H, halogen, phenyl, cyano, epoxy, alkyl of 18 carbon or less, alkylsilylmethyl of 18 carbon or less, aryl of 18 carbon or less, and siloxy.

2. The polycarbonate-based block polymer electrolyte of claim 1, wherein the conductive lithium salt is or more of lithium perchlorate (LiClO)₄) Lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF)₆) Bis (trifluoromethanesulfonyl) methyllithium [ LiC (SO)₂CF₃)₃]。

3. The polycarbonate-based block polymer electrolyte of claim 1, wherein the organic solvent is or more selected from the group consisting of 2-methyltetrahydrofuran, tetrahydrofuran, acetonitrile, 1, 2-dimethoxyethane, ethylene carbonate, ethylmethyl carbonate, ethylene carbonate, N-methylpyrrolidone (NMP), propylene carbonate, dimethyl carbonate, butylene carbonate, triethylene glycol dimethyl ether, γ -butyrolactone, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and dimethyl sulfoxide.

4. The polycarbonate-based block polymer electrolyte of claim 1, wherein the initiator or catalyst is of platinum water (Pt), Azobisisobutyronitrile (AIBN), Benzoyl Peroxide (BPO), dibutyltin bis (acetylacetonate), dibutyltin dilaurate, Azobisisoheptonitrile (ABVN), dimethyl Azobisisobutyrate (AIBME).

5. The kinds of polycarbonate-based block polymer electrolyte as claimed in claim 1, wherein the porous support material is kinds or more of polyethylene nonwoven fabric, polytetrafluoroethylene nonwoven fabric, polypropylene nonwoven fabric, glass fiber nonwoven fabric, cellulose nonwoven fabric.

6. The polycarbonate-based block polymer electrolyte as claimed in claim 1, which is prepared by mixing ethylene carbonate, C ═ C double bond compound, conductive lithium salt and organic solvent in corresponding mass fractions to prepare an electrolyte, uniformly stirring, adding initiator or catalyst in corresponding mass fractions, uniformly stirring, coating or immersing the electrolyte in a polytetrafluoroethylene mold containing a porous support material, and curing at 60-120 ℃ for 2-24 hours to form a film.

7. Use of the polycarbonate-based block polymer electrolyte as claimed in any one of claims 1-5, , wherein the separator between the positive and negative electrodes has a thickness of 10-500 μm.

8, solid lithium ion battery, which comprises a positive electrode, a negative electrode and a separator arranged between the positive electrode and the negative electrode, wherein the separator is polycarbonate-based block polymer electrolyte as defined in any one of claims 1-5 to .

9. The solid-state Li-ion battery of claim 8, wherein the positive active material of the solid-state Li-ion battery is lithium cobaltate (LiCoO)₂) Lithium-rich materials (LLOs), lithium iron phosphate (LiFeO)₄) Lithium manganese oxide, lithium Nickel Cobalt Aluminate (NCA), lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium manganese phosphate, lithium ion fluorophosphate, lithium nickelate (LiNiO)₂) or more, and the negative active material is metal lithium, metal lithium alloy, carbon-silicon composite material, lithium titanate,Preparing a positive electrode material, wherein the preparation comprises the steps of grinding and mixing 50-90% by mass of a positive electrode active material and 5-30% by mass of a conductive agent acetylene black, adding 1-15% by mass of polyvinylidene fluoride (PVDF), 1-15% by mass of an electrolyte mixed solution and 1-methyl-2 pyrrolidone (NMP), grinding and mixing to obtain the positive electrode material, coating the positive electrode material on the surface of an aluminum foil, and drying to obtain the positive electrode, wherein the metal lithium and a metal lithium alloy can be directly used as corresponding negative electrodes, preparing the negative electrode, and comprises the steps of grinding and mixing 30-80% by mass of the negative electrode active material and 5-30% by mass of the conductive agent acetylene black, adding 5-25% by mass of the polyvinylidene fluoride (PVDF), 1-15% by mass of the negative electrode alloy, coating 1-15% by mass of the negative electrode active material and 1-2% by mass of the negative electrode copper foil, grinding and mixing to obtain the negative electrode material, wherein the NMP is not counted in the mass of the positive electrode material, and the negative electrode material is coated on the surface of the conductive agent acetylene black, and the negative electrode material is dried to obtain the negative electrode material, and the negative electrode material, wherein NMP, the negative electrode material is not counted in the negative electrode material;

the electrolyte mixed solution of the solid lithium ion battery comprises 5-80% of ethylene carbonate, 5-80% of C-C double bond compound, 5-60% of conductive lithium salt, 5-80% of organic solvent and 0.5-5% of initiator or catalyst, wherein the electrolyte mixed solution is the same as the polycarbonate-based block polymer electrolytes in any items in claims 1-5.

10. The kinds of solid Li-ion batteries of claim 8 or 9, which are prepared by (1) ex-situ assembling process of positive and negative electrodes and said solid polymer electrolyte and (2) in-situ assembling process of injecting said electrolyte mixture into the battery system of positive, separator and negative electrodes, and curing at 60-120 ℃.

Technical Field

The invention relates to the field of lithium ion electrolytes, in particular to preparation and application of polycarbonate-based block polymer electrolytes.

Background

In recent years, zero carbon emission plans are realized, commercial lithium ion battery systems are increasingly applied to electric vehicles and mobile electronic equipment , at present, the commercial lithium ion batteries adopt conventional organic liquid electrolytes (lithium hexafluorophosphate + ethylene carbonate/propylene carbonate), and have series potential safety hazards such as pollution, corrosion and explosion due to the defects of high chemical activity, volatility, flammability and the like of the organic electrolytes.

Wright finds that the mixture of polyethylene oxide (PEO) and electrolyte salt has ionic conductivity, and promotes the research of polyelectrolyte to enter brand-new times.A polymer-based electrolyte has the defects of light weight, good chemical stability, easy film formation, good machining performance, diversified shapes and good wetting with an electrode, but the polymer electrolyte has low ionic conductivity, narrow electrochemical window, poor mechanical property and thermal stability and the like.A patent No. CN105591154A proposes polycarbonate all-solid-state polymer electrolytes, which comprise polycarbonate polymers, lithium salts and porous supporting materials, and the ionic conductivity is more than 10 at room temperature^-5S cm^-1The mechanical property is poor, and the electrochemical window is only 4.7V (vs. Li)⁺CN 105680094A discloses polyacrylate-based polymer electrolytes for sodium batteries and polymer sodium batteries formed by the polymer electrolytes, wherein the ionic conductivity of the electrolytes is 1 x 10^-4S cm^-1～8×10^-3S cm^-1Wide electrochemical window, and electrode materialPatent No. CN 104684949A provides multi-block copolymers with polyoxyethylene structural units on side chains and polymer electrolytes containing the multi-block copolymers, the multi-block polymer electrolytes have high ionic conductivity, poor mechanical property, difficult film formation and great difficulty in assembly process, and patent No. CN 109802174A discloses polycarbonate-based polymer electrolytes with the room-temperature ionic conductivity of more than 10^-3S cm^-1Electrochemical window 4.7V, which cannot be applied to LiNi_0.5Mn_1.5O₄And high-voltage anode materials.

Disclosure of Invention

The invention develops preparation and application of polycarbonate-based block polymer electrolytes by adopting ethylene carbonate, a C ═ C double-bond compound, conductive lithium salt, an organic solvent and an initiator, and the preparation process of the polymer electrolyte is simple and easy to control, has excellent mechanical property, has the thickness of 10-500 mu m and the ionic conductivity of 2 multiplied by 10^-4S cm^-1～5×10^-3S cm^-1(25 ℃), electrochemical window > 5V (vs. Li)⁺Li), has great innovation and practicability for the application of high-voltage cathode materials; the growth of lithium dendrites can be effectively inhibited, the lithium dendrites and electrode materials have good interface compatibility, and the rate capability and long cycle performance of the battery are improved; the polymer electrolyte has good flexibility and is suitable for flexible lithium ion battery devices of wearable electronic equipment; the working temperature range of the solid lithium ion battery is-25-100 ℃.

The technical scheme of the invention is as follows:

polycarbonate-based block polymer electrolyte is prepared by adopting raw materials comprising ethylene carbonate, a C-C double bond compound, conductive lithium salt, an organic solvent and an initiator, wherein the mass fraction of the ethylene carbonate is 5-80%, the mass fraction of the C-C double bond compound is 5-80%, the mass fraction of the conductive lithium salt is 5-60%, the mass fraction of the organic solvent is 5-80%, and the mass fraction of the initiator or the catalyst is 0.5-5%.

The structure of the polymer in the polycarbonate-based block polymer electrolyte is shown as a general formula 1:

wherein the value of n is 1-50000; the value of m is 1-50000; r₁、R₂、R₃And R₄ kinds selected from H, halogen, phenyl, cyano, epoxy, alkyl of 18 carbon or less, alkylsilylmethyl of 18 carbon or less, aryl of 18 carbon or less, and siloxy.

The conductive lithium salt is or more of lithium perchlorate (LiClO)₄) Lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF)₆) Bis (trifluoromethanesulfonyl) methyllithium [ LiC (SO)₂CF₃)₃]。

The organic solvent is or more selected from 2-methyltetrahydrofuran, tetrahydrofuran, acetonitrile, 1, 2-dimethoxyethane, ethylene carbonate, methyl ethyl carbonate, ethylene carbonate, N-methylpyrrolidone (NMP), propylene carbonate, dimethyl carbonate, butylene carbonate, triethylene glycol dimethyl ether, gamma-butyrolactone, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and dimethyl sulfoxide.

The initiator or catalyst is selected from platinum water (Pt), Azobisisobutyronitrile (AIBN), Benzoyl Peroxide (BPO), dibutyltin bis (acetylacetonate), dibutyltin dilaurate, Azobisisoheptonitrile (ABVN), and dimethyl Azobisisobutyrate (AIBME).

The porous support material is or more of polyethylene non-woven fabric, polytetrafluoroethylene non-woven fabric, polypropylene non-woven fabric, glass fiber non-woven fabric and cellulose non-woven fabric.

The preparation of the polycarbonate-based block polymer electrolyte comprises the following steps: preparing electrolyte from ethylene carbonate, a C-C double bond compound, conductive lithium salt and an organic solvent according to the corresponding mass fraction, and uniformly stirring; adding initiator or catalyst with corresponding mass fraction and stirring uniformly; coating or immersing the electrolyte into a polytetrafluoroethylene mould containing a porous support material, and heating and curing at 60-120 ℃ for 2-24 hours to form a film.

The solid-state lithium ion battery comprises: the electrolyte comprises a positive electrode, a negative electrode and a diaphragm arranged between the positive electrode and the negative electrode, wherein the diaphragm is the polycarbonate-based block polymer electrolyte.

The positive active material of the solid-state lithium ion battery is lithium cobaltate (LiCoO)₂) Lithium-rich materials (LLOs), lithium iron phosphate (LiFeO)₄) Lithium manganese oxide, lithium Nickel Cobalt Aluminate (NCA), lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium manganese phosphate, lithium ion fluorophosphate, lithium nickelate (LiNiO)₂) or more of the above-mentioned three, wherein the negative electrode active material is one or more of metal lithium, metal lithium alloy, carbon silicon composite material, lithium titanate, graphite, lithium metal nitride, antimony oxide, carbon germanium composite material and or more of lithium titanium oxide, the preparation of the positive electrode comprises the following steps of grinding and mixing the positive electrode active material accounting for 50-90% by mass and the conductive agent acetylene black accounting for 5-30% by mass, adding polyvinylidene fluoride (PVDF) accounting for 1-15% by mass, electrolyte mixed solution accounting for 1-15% by mass and 1-methyl-2 pyrrolidone (NMP) to obtain the positive electrode material, wherein the 1-methyl-2 pyrrolidone (NMP) is used for adjusting the viscosity and is not counted in the positive electrode material mass percentage composition, coating the positive electrode material on the surface of an aluminum foil, drying to obtain the positive electrode, and the metal lithium and metal lithium alloy can be directly used as the corresponding negative electrode, the negative electrode comprises the steps of grinding and mixing the negative electrode active material accounting for 30-80% by mass, the conductive agent accounting for 5-30% by mass, the negative electrode mixed solution accounting for 5-15% by mass, and the conductive agent (NMP) and the mixed solution accounting for 1-15% by mass, adding the polyvinylidene fluoride (NMP) to the negative electrode mixed solution, wherein the electrolyte mixed solution accounting for 1-2% by mass, the negative electrode material, the negative electrode mixed solution, andthe ketonic acid (NMP) is used for adjusting the viscosity and is not counted in the mass percentage composition of the negative electrode material; and coating the copper foil surface, and drying to obtain the cathode.

The electrolyte mixed liquid of the solid lithium ion battery comprises the following components: the electrolyte mixed liquid comprises 5-80% of ethylene carbonate, 5-80% of C-C double bond compound, 5-60% of conductive lithium salt, 5-80% of organic solvent and 0.5-5% of initiator or catalyst (the specific selection of each substance in the electrolyte mixed liquid is the same as that of each raw material component of the polycarbonate-based block polymer electrolyte).

The preparation process of the solid lithium ion battery comprises the following steps of (1): ex-situ assembly processes-positive and negative electrodes and the solid polymer electrolytes described above; (2): and (3) in-situ assembly technology, namely injecting the electrolyte mixed solution into a battery system of a positive electrode, a diaphragm and a negative electrode, and curing at 60-120 ℃.

The invention has the innovativeness and practicability that:

the block polymer electrolyte is prepared from ethylene carbonate, a C ═ C double bond compound, conductive lithium salt, a porous support material, an organic solvent and an initiator. The thickness of the polymer electrolyte is 20-200 μm; ion conductivity 2X 10^-4S cm^-1～5×10^-3S cm^-1(25 ℃), electrochemical window > 5V (vs. Li)⁺/Li), has great innovation and practicability for the application of high-voltage cathode materials. The polymer electrolyte can be prepared by in-situ polymerization without adding an organic solvent in the preparation process, the process is simple, and the product shrinkage is small; the lithium dendrite growth is effectively inhibited by good flexibility, the lithium dendrite growth inhibitor has good interface compatibility with electrode materials, the rate capability and the long cycle performance of the battery are improved, the safety and the practicability of the lithium battery are greatly improved, and the lithium battery can be applied to all-solid-state lithium batteries (including lithium-sulfur batteries), all-solid-state lithium ion batteries and other secondary high-energy lithium batteries.

Drawings

FIG. 1 is a voltammetric linear scan of a polymer electrolyte in example 2.

Detailed Description

The present invention is illustrated below by specific examples, which are provided for better understanding of the present invention and are not intended to limit the scope of the present invention in any way.

Preparation of block polymer electrolyte: