273 results about "Dimethyl carbonate" patented technology

The application provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte. The positive electrode sheet and the negative electrode sheet are stacked, and the separator is arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet comprises a positive electrode main body part and a positive electrode tab part. The ratio of the long side size to the short side size of the positive electrode main body part is (3-8):1. The negative electrode sheet comprises a negative electrode main body part and a negative electrode tab part. The long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by 2-9 mm. The long side of the separator exceeds the long side edge of the negative electrode main body part by 2-10 mm. The electrolyte comprises a solvent. The solvent comprises one or more of dimethyl carbonate and a linear carboxylic acid ester having a structure shown in formula (1). In formula (1), R1 and R2 each independently comprises a C1-C5 alkyl or a halogenated alkyl. The battery monomer has a high energy density, good cycle performance and low self-discharge.

The application discloses an alkali ion type covalent organic framework material and a preparation method and application thereof, wherein 2,4,6-tris(4-formylphenyl)-1,3,5-triazine, 1,4-diisocyanobenzene and 2-aminopyridine are used as building units, a covalent organic framework containing pyrimidine is obtained through a condensation reaction, and then a quaternary ammonium reaction and an ion exchange reaction are sequentially performed to obtain the alkali ion type covalent organic framework.The alkali ion type covalent organic framework material prepared by the application has rich alkali sites, developed pore structures and good chemical stability, exhibits good catalytic performance as a catalyst for one-pot preparation of dimethyl carbonate from CO2, an epoxide compound and methanol, and also shows good cycle stability.

The application discloses a kind of carbon dioxide methyl ester raw gas purification filter pollution devices, it includes horizontally arranged cylinder, coaxial tower type ladder filter assembly and translation pneumatic purging assembly are arranged in the cylinder, the tower type ladder filter assembly includes several end face filter parts and cylinder filter parts that are alternately connected in sequence;The beneficial effects of the application: the tower type ladder filter assembly of the application is designed to filter carbon dioxide methyl ester raw gas, the tower structure can effectively increase the filter area, thereby improving the filtering efficiency;Tower type ladder filter assembly has matching end face filter parts and cylinder filter parts, with axial airflow and radial airflow filtering function, according to the gas direction to axial filtration as main, radial filtration as auxiliary, long service life;According to the actual use characteristics of end face filter parts and cylinder filter parts, design translation pneumatic purging assembly and spray cleaning assembly to clean tower type ladder filter assembly, cleaning is fast and efficient.

The invention relates to a method for continuously synthesizing methyl trifluoroethyl carbonate through three-stage series connection, which comprises the following steps of: reacting dimethyl carbonate and chlorine in the presence of an activated carbon loaded ferric trichloride catalyst, introducing into a gas-liquid separator after the reaction is ended, separating to obtain reaction feed liquid a and unreacted chlorine, and returning the unreacted chlorine to continue the reaction; sufficiently mixing a 50wt% sodium hydroxide solution, trifluoroethanol and the reaction material liquid a, and then carrying out constant-temperature reaction to obtain a reaction material liquid b; methanol and the reaction feed liquid b are fully mixed for a reaction, after the reaction is finished, a reaction product is taken out, a lower-layer methyl trifluoroethyl carbonate crude product is obtained through separation and then rectified and purified in a rectifying tower, and finally high-purity methyl trifluoroethyl carbonate is obtained. Through the design of the micro-channel reactor and the gas-liquid separator, use and recovery of chlorine are effectively controlled, and the safety risk is reduced; meanwhile, the separation cost is low, the energy consumption is reduced, and the high-purity methyl trifluoroethyl carbonate is obtained.

The present invention relates to a method of preparing a heterogeneous linear carbonate, the method including performing a transesterification reaction of dimethyl carbonate (DMC) and ethanol (EtOH) in the presence of a catalyst, wherein the catalyst is one or more selected from the group consisting of lithium methoxide (LME), lithium ethoxide (LEE), sodium methoxide (SME), sodium hydroxide (NaOH), and a mixture thereof, and the catalyst is input in a state of being dissolved in a sulfoxide-based solvent.

This invention relates to an alcohol-based fuel additive, its preparation method, and its application, belonging to the technical field of diesel fuel additives. The additive, by weight, comprises: a mixture of C3-C10 fatty alcohols, fatty acid methyl esters, methyl tert-butyl ether, isoamyl nitrate, dimethyl carbonate, and diesel fuel. The mass ratio of methyl tert-butyl ether to dimethyl carbonate is [value missing]. This invention employs a stepped feeding process, solving the problem of combustion improver failure caused by high shear heat generation by cooling the fuel before adding isoamyl nitrate, and ensuring long-term fuel stability at -10°C using a specific polarity gradient ratio. The fuel prepared by this invention has a high cetane number, strong power, and good anti-stratification effect, making it suitable for compression ignition engines.

The present application relates to a kind of preparation method of trifluoromethyl pyrazole compound, belong to the technical field of organic synthesis.The specific method is: (1) trifluoroacetyl ethyl acetate is first with hydrazine hydrate cyclization reaction and generates compound of formula III;(2) under the catalysis of base, compound of formula III is reacted with difluoromethylation reagent and generates compound of formula II;(3) compound of formula II is reacted with methylating agent and obtains compound of formula I;The difluoromethylation reagent is difluoro-monochloromethane or sodium difluoro-monochloroacetate;The methylating agent is chloromethane, bromomethane, iodomethane, dimethyl sulfate or dimethyl carbonate.The present application is prepared by changing reaction route, and the higher-priced raw material methylhydrazine is replaced, and isomer impurity is no longer generated in the product prepared.Not only raw material cost is reduced, but also the purity of product is improved.

SOLVENT COMPOSITIONS The present invention relates to a solvent composition for solvent-based paints or other coatings characterized in that it comprises a combination of dimethyl glutarate and at least one other compound selected from isobutyl acetate, ethyl lactate, dimethyl 2-methylglutarate, 2-methyltetrahydrofuran, ethyl acetate, cyclopentyl methyl ether, dithoxymethane, dimethyl carbonate, dimethyl succinate, benzyl alcohol, dimethyl adipate, and glyceryl triacetate. Fig. 1

Lithium secondary battery, comprehensive a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein: the positive electrode comprises a positive electrode active material, wherein the positive electrode active material comprises lithium iron phosphate particles and the positive electrode has a loading amount of 450 mg / 25 cm² 2 up to 740 mg / 25 cm 2 exhibits; and the non-aqueous electrolyte comprises a lithium salt, an organic solvent and an additive, wherein the organic solvent comprises a solvent based on a cyclic carbonate and a solvent based on a linear carbonate, wherein the solvent based on a cyclic carbonate comprises ethylene carbonate and the solvent based on a linear carbonate comprises dimethyl carbonate, the additive comprises vinylene carbonate and the dimethyl carbonate is present in an amount of 5 vol% to 75 vol% in the organic solvent and the weight ratio of vinylene carbonate to dimethyl carbonate is greater than 0 to 0.2 or less.

The application discloses a preparation of isosorbide catalyst and its preparation method and application. The catalyst is an organic / inorganic hybrid material, wherein the organic component comprises a functional group containing two or more N atoms and a hydrophobic group without nitrogen, and the inorganic component is a mesoporous silica material. The catalyst provided by the application is applied to the reaction of sorbitol and dimethyl carbonate to prepare isosorbide, and has high catalytic performance.

The invention provides yellow glue resistant to corrosion of a plasticizer and a preparation method of the yellow glue. The yellow glue is prepared from a polyurethane prepolymer, a chloroprene rubber sheet, methyl methacrylate, benzoyl peroxide, an anti-aging agent, butanone, cyclohexane, dimethyl carbonate and tackifying resin. The polyurethane prepolymer is prepared from the following components in parts by weight: 10 to 14 parts of 1, 4-butanediol adipic acid polyester polyol, 4 to 8 parts of polycaprolactone polyol, 1 to 3 parts of diphenylmethane diisocyanate, 0.05 to 0.15 part of 1, 6-hexanediol, 1 to 2 parts of hydroxyethyl methacrylate, 0.01 to 0.03 part of organic bismuth catalyst and 75 to 80 parts of butanone. The polyurethane prepolymer with specific crystallization performance is synthesized through cooperation of polycaprolactone polyol and polyester polyol, and the yellow glue is endowed with excellent plasticizer corrosion resistance and low-temperature activation capacity. Active groups in the polyurethane prepolymer are subjected to graft copolymerization with the chloroprene rubber adhesive and MMA, and a plasticizer-resistant polyurethane chain segment is introduced into a molecular chain of the chloroprene rubber adhesive, so that a hard segment-soft segment alternating block structure is formed, and corrosion resistance and viscoelasticity are both considered.

The application discloses a sensor with a bionic olfactory positioning function, comprising a gate electrode, a dielectric layer and an electrode; the dielectric layer is arranged between the gate electrode and the electrode; and the dielectric layer comprises a porous structure zwitterionic polymer film. Through the combination of the high sensitivity of the sensor to dimethyl carbonate (DMC) and the application method, accurate positioning of a DMC leakage position is realized, and meanwhile, the sensor has the characteristics of high sensitivity, durability and excellent intelligent bionic positioning, and overcomes the positioning function that traditional sensors do not have.

The utility model relates to the field of catalyst recycling technology, especially relates to a carbonic acid dimethyl ester synthesis is with catalyst recycling device. Including recovery jar, the recovery jar is installed with the stirring assembly for stirring catalyst, the recovery jar is installed with the heating assembly for heating catalyst, recovery assembly is installed on the recovery jar for recycling the hot air of discharge, the utility model discloses through the setting of recovery assembly, and the recovery jar exhausts the hot and humid gas and exchanges heat with the outside air in the heating box, and the preheating of air is carried out, thereby reducing the temperature difference of the air that advances the wind and heats to dry exhaust air, realizes the recycling of the waste heat in the hot and humid gas, reduces the energy waste that the direct discharge of heat causes, and reduces the energy consumption cost of heating process.

This invention discloses a method for synthesizing cefotiam, using 7-aminocephalosporanic acid (7-ACA) as the parent nucleus and introducing a 4-dimethylaminopyridine-dimethyl carbonate composite catalytic system. The reaction is carried out in a one-pot process involving 3-position nucleophilic substitution, 7-position amidation, and simultaneous deprotection in a green mixed solvent of ionic liquid [BMIM]BF₄-water with 1-(2-dimethylaminoethyl)-1H-5-mercapto-tetrazole and compound I. This method simplifies the process, improves selectivity, produces a high-purity product with stable yield, and is suitable for industrial production.

The invention discloses a hand brushing and spraying dual-purpose odorless anti-yellowing transparent polyurethane primer suitable for various base materials and a preparation method thereof. The primer mainly comprises a component A, a component B and a component C, the component A is mainly prepared from odorless coconut oil alkyd resin, zinc stearate, a defoaming agent, a flatting agent, an anti-settling agent, functional resin and an organic solvent; the component B is mainly prepared from an HDI (hexamethylene diisocyanate) tripolymer, a TDI (toluene diisocynate) tripolymer, a dehydrating solvent and a dehydrating agent; the component C is mainly prepared from dimethyl carbonate, n-butyl acetate and propylene glycol methyl ether acetate; the anti-settling agent is a mixed solution of polyamide wax slurry 6900-20X and n-butyl acetate, and the mass concentration of the polyamide wax slurry 6900-20X in the mixed solution is 40%; the functional resin is a mixed solution of cellulose acetate butyrate CAB-381-0.5 and n-butyl acetate, and the mass concentration of the cellulose acetate butyrate CAB-381-0.5 in the mixed solution is 20%. The odorless yellowing-resistant transparent polyurethane primer has the advantages of no blistering, no prickly heat, suitability for various base materials, dual purposes of hand brushing and spraying, and the like.

The utility model relates to carbonic acid dimethyl ester production technical field, and disclose a kind of carbonic acid dimethyl ester production device of continuous feeding, the bottom surface of feed hopper is fixedly installed with conveying pipe, the inside of conveying pipe is fixedly installed with gear, the outside of gear is engaged to be connected with transmission crawler belt, the side surface of transmission crawler belt is fixedly installed with hopper, the bottom surface of conveying pipe is fixedly installed with discharge hopper, the bottom surface of discharge hopper is fixedly installed with recombinant component separation device.This carbonic acid dimethyl ester production device of continuous feeding, raw material is entered into conveying pipe by feed hopper, in conveying pipe, raw material will fall into hopper, hopper is driven by gear to transport raw material by transmission crawler belt, compared with ordinary transmission device, transmission crawler belt can adapt to bending lifting operation, and it has longer service life, and individual component can be replaced and repaired, maintenance cost is also lower in later period, hopper not only can transport solid raw material, but also can transport liquid raw material.

The preparation method comprises the following steps: mixing aliphatic diol with dimethyl carbonate, adding isophorone diisocyanate and a carboxyl-containing chain extender, and adding a neutralizing agent and an organic solvent, so as to obtain a water-based polycarbonate emulsion; adding a phosphate-containing chain extension monomer into the high-molecular-weight polycarbonate polyol intermediate, heating for condensation polymerization to obtain phosphate-containing active resin, and heating the low-molecular-weight polycarbonate polyol intermediate and alkylsilane for condensation polymerization to obtain a silane modified polycarbon oligomer; the preparation method comprises the following steps: mixing a water-based polycarbonate emulsion, phosphate-containing active resin and a silane modified polycarbon oligomer, and adding a nano inorganic filler to obtain a water-based high-activity polycarbon coating; after the water-based high-activity poly-carbon coating is applied to the surface of a base material, a water-based high-activity poly-carbon coating is formed on the surface of the base material. The problems of adhesion attenuation and coating blistering and falling under high-temperature and high-humidity conditions are effectively inhibited.

The utility model relates to rectifying tower technical field, and disclose a kind of rectifying tower reboiler for dimethyl carbonate production, including reboiler main body, the bottom of reboiler main body is fixedly connected with liquid inlet pipe, the top of reboiler main body is fixedly connected with gas outlet pipe, the side of reboiler main body upper end is fixedly connected with steam inlet pipe, the side of reboiler main body lower end is fixedly connected with condensate outlet pipe, the other side of reboiler main body lower end is fixedly connected with two connecting pipes, the other end of two connecting pipes is connected with replacement component, the other end of two replacement components is connected with two liquid level meters respectively.The kind of rectifying tower reboiler for dimethyl carbonate production, by liquid level meter real-time monitoring and maintaining reboiler main body in higher than condensate outlet pipe mouth liquid level, form liquid seal and block steam into subsequent process, reduce steam consumption and unit production cost.

The present application relates to a kind of preparation methods and systems of electronic grade dimethyl carbonate prepared from dimethyl oxalate, the method comprises the following steps: dimethyl oxalate is preheated and sent into decarboxylation reactor to carry out decarboxylation reaction, carbon monoxide, dimethyl carbonate and other light components are extracted from the top of decarboxylation reactor, and heavy components are extracted from the bottom of decarboxylation reactor;Carbon monoxide, dimethyl carbonate and other light components extracted are separated after gas-liquid, and liquid phase dimethyl carbonate is sent into rectifying column to carry out rectification purification;Electronic grade dimethyl carbonate product is obtained by crystallization purification in refrigeration crystallization device after rectification, and crystallization mother liquor returns rectifying column;Decarboxylation reactor is three-stage reaction tower, and rectifying section, reaction section, stripping section are sequentially from top to bottom.The present application is completely reacted by the design of three-stage decarboxylation reactor;Heavy components generated are extracted in real time, and catalyst stability is high;Electronic grade DMC is prepared by using rectifying column coupled with crystallization tower, and the yield of DMC is significantly improved.

The invention provides a one-pot synthesis method of 1, 3-dimethyl-2-imidazolidinone, which comprises the following steps: mixing a basic catalyst, an ionic liquid and methanol, adding ethylenediamine to synthesize 2-imidazolidinone under a low-temperature condition, and raising the temperature to enable the 2-imidazolidinone and dimethyl carbonate to have an N-methylation reaction. According to the synthesis method, the ionic liquid is adopted as the catalyst, on one hand, the ionic liquid serves as a phase transfer catalyst, and the acid binding effect of the acid binding agent is enhanced; on the other hand, as a carbene catalyst, dimethyl carbonate is activated, so that the acylation and methylation reaction efficiency is improved.

The invention belongs to the field of fuel additive preparation, and relates to a preparation method of an alcohol-based oxygen-containing fuel additive. In order to solve the problems that an existing carbonic ester additive is relatively low in boiling point and is not matched with a diesel distillation range, the invention develops a special catalyst and a preparation process for preparing an alcohol-based oxygen-containing fuel additive, the catalyst takes a hierarchical pore molecular sieve as a carrier, and a potassium alcoholate active component and an amphiphilic molecule linking agent are introduced. Then catalyzing the ester exchange reaction of dimethyl carbonate and butanol by using the catalyst to generate a mixture of methyl butyl carbonate, dibutyl carbonate and the like, and fractionating to obtain the alcohol-based oxygen-containing fuel additive which has a proper boiling point and can be used for remarkably improving the oxygen content of the fuel.

The invention provides a battery monomer, a battery device and a power utilization device, the battery monomer comprises a positive pole piece, an isolating membrane, a negative pole piece and an electrolyte, the positive pole piece and the negative pole piece are laminated, and the isolating membrane is arranged between the positive pole piece and the negative pole piece; the positive pole piece comprises a positive pole main body part and a positive pole lug part, and the ratio of the long side size to the short side size of the positive pole main body part is (3-8): 1; the negative pole piece comprises a negative pole main body part and a negative pole lug part, the long side of the negative pole main body part exceeds the edge of the long side of the positive pole main body part by 2mm-9mm, and the long side of the isolating membrane exceeds the edge of the long side of the negative pole main body part by 2mm-10mm; the electrolyte comprises a solvent, and the solvent comprises one or more of dimethyl carbonate and linear carboxylic ester with a structure as shown in a formula (1); in the formula (1), R1 and R2 respectively and independently comprise C1-C5 alkyl or halogenated alkyl. The battery monomer has relatively high energy density, relatively good cycle performance and relatively low self-discharge.

The invention discloses a preparation method of N-methyl o-fluoroaniline, which is characterized in that o-fluoroaniline is used as a starting raw material, and a target product is efficiently synthesized through three steps of reaction: step 1, in the presence of a solvent and alkali, o-fluoroaniline and acetyl chloride are acetylated at low temperature to generate 2-fluoro-acetanilide, and the product is directly used for the next step after being roughly purified; 2, under the action of a solvent and alkali, carrying out controllable methylation on the 2-fluorine-acetanilide and dimethyl carbonate to obtain 2-fluorine-N-methylacetanilide; and 3, removing acetyl protection through acidic hydrolysis, and adding sodium thiosulfate to prevent oxidation to finally obtain a high-purity product. According to the method, excessive methylation is avoided through an acetyl protection strategy, the process does not need high-risk operations such as ultralow temperature and high pressure, the operation is simple and convenient, the energy consumption is low, and the product purity is gt; the total yield reaches 79.86%, and the method is green, safe and suitable for industrial production.

The invention relates to the technical field of catalyst materials, in particular to a method for synthesizing a dimethyl carbonate catalyst through a hydrothermal method and application. Comprising the following steps: A, preparing poloxamer into a solution, adding HAc and NaClO4, and uniformly mixing to obtain a mixture; b, (NH4) 2Ce (NO3) 6 and H2BDC are added into the mixture in the step A to be stirred, mixed and reacted, the catalyst is obtained through centrifugal separation, washing, soaking, vacuum drying and calcination, crystal grains of the catalyst are reduced, and the specific surface area, the number of acid-base sites and the oxygen vacancy concentration are all greatly improved.

The application discloses a battery monomer, a battery and a power utilization device, and belongs to the technical field of batteries. The battery monomer comprises an electrode assembly, a shell, and an end cover. The shell and the end cover form a space for accommodating the electrode assembly, and the end cover is provided with a pressure relief mechanism. An electrolyte comprises a solvent and an electrolyte salt. The solvent comprises dimethyl carbonate, and the electrolyte salt comprises a lithium bisfluorosulfonylimide salt. Along the thickness direction of the end cover, the gap D between the electrode assembly and the inner side of the pressure relief mechanism satisfies 1mm<=D<=7mm. The capacity Q of the battery monomer satisfies 30Ah<=Q<=40Ah. The battery monomer has the advantages of fast charging capacity, high energy density and high reliability.

This invention discloses a novel method for preparing a clean fuel additive, relating to the field of clean fuel additive technology. Its components include: a main cleaning agent: Mannich base; a dispersant: polyetheramine; a surfactant: highly active polyisobutylene; an antioxidant: N,N-di-sec-butyl-p-phenylenediamine; an octane booster: dimethyl carbonate; a solvent: 120# solvent oil; a combustion improver: C9-C11 mixed olefins; a stabilizer: trimethylolpropane; an ignition promoter: nitrobenzene; and auxiliary additives: n-dodecane, sodium polystyrene sulfonate, and eugenol methyl ether. This invention achieves a significant synergistic effect among the core components such as Mannich base, polyetheramine, polyisobutylene, amine antioxidants, and dimethyl carbonate. This synergistic effect allows the additive to comprehensively optimize the cleanliness, anti-knock properties, stability, and combustion efficiency of fuel at a relatively low total addition amount.

The invention belongs to the technical field of separation and purification, and particularly relates to a method for separating a methanol-dimethyl carbonate azeotrope system, which adopts a system for separating a methanol-dimethyl carbonate azeotrope and adopts a eutectic solvent as an extracting agent for extractive distillation. The hydrogen bond acceptor of the deep-eutectic solvent is choline chloride, and the hydrogen bond donor of the deep-eutectic solvent is malonic acid or urea. According to the method, the choline chloride deep eutectic solvent which is lower in cost, simpler and more convenient to prepare and more environmentally friendly is selected as the extracting agent, systematic process parameter optimization and equipment configuration design are carried out according to the high-viscosity characteristic of the choline chloride deep eutectic solvent, and stable, efficient and long-period operation of the high-viscosity green solvent in the continuous extractive distillation process is successfully achieved; the target of separating the methanol and the dimethyl carbonate from the binary mixture is achieved, the final yield of the methanol and the dimethyl carbonate can reach 99% or above, the product purity can reach 99.5% or above, and compared with a traditional solvent separation method, the energy consumption is greatly reduced, the equipment cost is saved, and the method is suitable for industrial production. The strict standard of the high-end chemical industry and the fine chemical industry on the raw material purity can be reached.

The application provides application of dimethyl carbonate as a chronic obstructive pulmonary disease diagnostic marker and belongs to the technical field of biomedical detection. The application first finds that the detection rate of dimethyl carbonate in exhaled air is significantly related to chronic obstructive pulmonary disease, and the detection rate of dimethyl carbonate in exhaled air of a chronic obstructive pulmonary disease patient is significantly higher than that of a healthy person. The ROC curve analysis result shows that dimethyl carbonate has extremely high specificity as a biomarker for diagnosing chronic obstructive pulmonary disease, and therefore can be used as a detection target for the diagnosis of chronic obstructive pulmonary disease patients, and has good practical application value.

The invention provides a waste lithium ion battery electrolyte recovery process and equipment, and relates to the technical field of solid waste resourceful treatment.The waste lithium ion battery electrolyte recovery process comprises the following steps that S1, a completely-discharged waste lithium ion battery is decomposed in an inert gas glove box, scraps such as adhesive tape are removed, the battery is immersed in a dimethyl carbonate solution, ultrasonic stirring, standing and filtering are conducted, and the waste lithium ion battery is obtained; a mixed solution is obtained; and S2, the mixed solution is transferred into a vacuum distillation device to be distilled, dimethyl carbonate and an electrolyte are obtained, and dimethyl carbonate can be circularly used for extraction of other waste electrolytes. According to the scheme, through dimethyl carbonate extraction and vacuum distillation, efficient recovery of the electrolyte is finally achieved, lithium salt is recovered in the form of lithium fluoride, key metal of the lithium battery is recovered, fluoride and phosphate can serve as high-purity products to be reused, the resource utilization efficiency is improved, and emission of toxic gas is avoided.

The invention discloses a secondary battery, an electrolyte, and a device including the same. The secondary battery comprises an electrolyte, the electrolyte comprises an organic solvent, and the organic solvent comprises cyclic carbonate and chain carbonate; the chain carbonate ester comprises dimethyl carbonate; the mass percentage of the dimethyl carbonate in the chain carbonate is greater than or equal to 9 wt% and less than 50 wt%; wherein based on the total mass of the organic solvent, the mass percentage of the carboxylic ester in the organic solvent is less than 5wt%, and the conductivity of the electrolyte at-20 DEG C is greater than or equal to 2.5 mS / cm. The secondary battery has excellent low-temperature power and 45 DEG C cycle performance.