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CN-116053577-B - Polyurea and polythiourea super-ion solid electrolyte and preparation method and application thereof

CN116053577BCN 116053577 BCN116053577 BCN 116053577BCN-116053577-B

Abstract

The invention relates to the field of polymer solid-state batteries, and discloses a polyurea and polythiourea super-ion solid-state electrolyte, a preparation method and application thereof. The super-ionic solid electrolyte comprises a polymer matrix and metal lithium salt, wherein the polymer matrix is one of main chain type polythiourea, side chain type polythiourea or polyurea. According to the invention, thiourea groups or urea groups are introduced into a main chain and a side chain of the polymer to form strong supermolecular interaction with lithium salt anions, so that the dissolution of lithium salt in a polymer matrix is promoted, and a novel transmission mechanism is introduced, so that the super-ionic solid electrolyte with high transfer number and high ionic conductivity is obtained.

Inventors

  • HUANG MINGJUN
  • HU RONGRONG
  • LANG CHAO
  • DAI SHUQI
  • HE JUNXIA
  • CUI JINYI

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20230118

Claims (6)

  1. 1. A solid electrolyte comprises a polymer matrix and metal lithium salt, and is characterized in that the polymer matrix is one of main chain type polythiourea, side chain type polythiourea or polyurea, the structure of the main chain type polythiourea is shown as a formula 1, the structure of the side chain type polythiourea or polyurea is shown as a formula 2, 1 (1) 2, 2 R 1 and R 2 are 、 One or two of the following components; R 3 is ureido-NH- (c=o) -NH-or thioureido-NH- (c=s) -NH-; r 4 is 、 、 、 、 、 One of them.
  2. 2. A preparation method of the solid electrolyte according to claim 1 is characterized by comprising the following steps of uniformly mixing a polymer matrix and lithium salt after being dissolved respectively, pouring the mixture into a polytetrafluoroethylene plate, and drying the mixture to obtain the super-ionic solid electrolyte, wherein the polymer matrix is one of main chain type polythiourea, side chain type polythiourea or polyurea; The preparation method of the main chain type polythiourea polymer matrix comprises the following steps: S1, mixing sulfur, aliphatic diamine and diisocyanide in a mass ratio in an inert gas atmosphere, and dissolving the mixture in N, N-dimethylformamide; s2, stirring the mixture obtained in the step S1 for 4-5 hours at 40-50 ℃, cooling to room temperature, and dripping the reaction mixture into a mixed solvent of n-hexane and dichloromethane through a cotton filter; the aliphatic diamine in the step S1 is one of 1, 6-diaminohexane and 1, 8-diamino-3, 6-dioxaoctane, and the diisocyanide in the step S1 is one of 1, 6-diisocyanohexane and 1, 2-bis (2-isocyanoethoxy) ethane; The preparation method of the side chain type polythiourea or polyurea polymer matrix comprises the following steps: dissolving aliphatic amine or aromatic amine and isocyanate or thioisocyanate in tetrahydrofuran according to mass ratio under inert gas atmosphere and 0 ℃ and mixing, reacting the obtained mixture for 4-5 hours at 0-5 ℃, and reacting for 12-14 hours after the mixture is heated to room temperature; t2, dissolving the monomer obtained in the step T1 in N, N-dimethylformamide in an inert gas atmosphere, adding azodiisobutyronitrile, uniformly mixing, stirring the obtained mixture at 60-70 ℃ for reaction for 24-25 hours, precipitating and centrifuging the reaction mixture by using a precipitating agent, and drying the obtained precipitate in vacuum to obtain a side chain type polythiourea or polyurea polymer; the fatty amine in the step T1 is n-butylamine, the aromatic amine is one of aniline, 4-n-butylaniline, para-trifluoromethylaniline, m-di (trifluoromethyl) aniline and 2,3,4,5, 6-pentafluoroaniline, the isocyanate in the step T1 is ethyl 2-isocyanate acrylate, and the thioisocyanate is methyl 2-isothiocyanacetate.
  3. 3. The method for preparing a solid electrolyte according to claim 2, wherein the lithium salt is one of lithium perchlorate, lithium bis (trifluoromethylsulfonyl) imide, lithium tetrafluoroborate, and lithium bis (difluorosulfimide), and the lithium salt accounts for 1% -50% of the total mass of the solid electrolyte.
  4. 4. The method for producing a solid electrolyte according to claim 2, wherein 0.5659mg of azobisisobutyronitrile is added per gram of monomer in step T2.
  5. 5. The method of preparing a solid electrolyte according to claim 2, wherein the precipitant in step T2 is a water/methanol mixed solvent, and the volume ratio of water to methanol is 1:4.
  6. 6. A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the solid electrolyte of claim 1.

Description

Polyurea and polythiourea super-ion solid electrolyte and preparation method and application thereof Technical Field The invention belongs to the field of polymer solid electrolyte materials, and particularly relates to a polyurea and polythiourea super-ion solid electrolyte, and a preparation method and application thereof. Background Lithium ion batteries have been widely used in daily life due to their high energy density, high power, long service life, and excellent electrochemical properties. However, in commercial lithium ion batteries, potential safety hazards of leakage and flammability exist in the practical application process, and side reactions occur with electrode materials to cause irreversible attenuation of battery capacity and the like. At the same time, the next generation energy storage systems require higher energy density and safety. Therefore, lithium metal anode solid-state batteries have been attracting worldwide research in recent years. In order to realize a lithium metal anode solid state battery, development of a solid state electrolyte having high ionic conductivity, high mechanical strength, good interface compatibility, good processability, and chemical/electrochemical stability is urgently required. The inorganic/ceramic solid electrolyte has higher mechanical strength, high room temperature ionic conductivity and wide chemical window, but has poor chemical and electrochemical stability, poor processability and large solid/solid interface impedance, which limits the further application. Another option is a polymer solid electrolyte with easy processability and flexibility. At present, the polymer solid electrolyte is mainly made of polyethylene oxide (PEO) materials, and the problems of low ionic conductivity (10 -5～10-6S·cm-2), low ion migration number (0.1-0.2), weak mechanical strength and the like at room temperature are caused by strong coupling of ion diffusion and polymer chain segment movement, so that the application of the polymer solid electrolyte is severely limited. In order to improve the polymer solid electrolyte performance, various strategies have been proposed, including the incorporation of nanofillers (s.jayanthi and b.sundaresan, ionics,2015,21,705-717.), single ion conductive polymers (W.Zhang, chem.Mater.2021,33, 524-534), block copolymers (M.Jia, adv.Funct.Mater.2021,31,2101736), and the like. However, none of the above methods is sufficient to meet the practical application requirements of the battery. In order to break the inherent contradiction between ionic conductivity, lithium ion transport number and mechanical strength in polymer electrolytes, the development of a novel transport mechanism for polymer solid electrolyte materials is in need of a solution. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a polyurea and polythiourea super-ion solid electrolyte, and a preparation method and application thereof. The solid electrolyte has high mechanical strength, high room temperature ionic conductivity and high ionic conductivity. The specific technical scheme of the invention is as follows: a solid electrolyte of polyurea or polythiourea is prepared from polymer matrix and metallic lithium salt. The introduction of thiourea or urea on the polymer backbone or side chains is based on the advantages of 1) the formation of a tight bond between thiourea or urea and lithium ion anions through synergistic electrostatic and hydrogen bonding, promoting the dissolution of lithium salts in the polymer matrix, and 2) the combination of high-density thiourea or urea and anions anchored along the polythiourea or polyurea chains as polar sites, building ion conduction channels and assisting the movement of lithium ions in a manner of decoupling the movement of polymer segments. Through the introduction of the novel transmission mechanism and the optimization of polymer materials, the super-ionic solid electrolyte has high transfer number, high ionic conductivity and excellent mechanical strength. The polymer matrix is one of main chain type polythiourea, side chain type polythiourea or polyurea. The main chain type polythiourea has a structure shown in a formula 1, and the side chain type polythiourea or polyurea has a structure shown in a formula 2. R 1 and R 2 areOne or two of the following components; R 3 is ureido or thiourea; r 4 is One of them. The invention provides a preparation method of a polyurea and polythiourea super-ion solid electrolyte, which comprises the following steps of respectively dissolving a polymer matrix and lithium salt, uniformly mixing, pouring into a polytetrafluoroethylene plate, and drying to obtain the super-ion solid electrolyte. The lithium salt is one of lithium perchlorate, lithium bis (trifluoromethylsulfonyl) imide, lithium tetrafluoroborate and lithium bis (difluorosulfimide), and accounts for 1% -50% of the total mass of the solid electrolyte. The main chain type polythioure