In-situ preparation method and application of amido composite solid electrolyte

Abstract

The invention discloses an in-situ preparation method and application of an amido composite solid electrolyte. An isocyanate derivative, a small-molecular-weight hydroxyl organic monomer, high-molecular polyethylene oxide (PEO), a lithium salt and a surface film-forming additive are used as main raw materials, dissolved in a solvent, stirred and mixed, and uniform slurry is obtained; then the surface of a positive electrode material of the solid battery is coated with the mixed slurry to form a slurry film; and the positive electrode material coated with the slurry film is heated until the slurry film is cured into a solid film to obtain the amido composite solid electrolyte tightly combined with the surface of the positive electrode material. The prepared amino composite solid electrolyte film is combined with the surface of a solid battery positive electrode material, a secondary lithium ion solid battery is obtained through assembling, and the secondary lithium ion solid battery is suitable for the conditions that the working potential is larger than or equal to 4.3 V vs.Li<+>/Li, and the working temperature is not higher than 40 DEG C. The method disclosed by the invention is relatively simple in process, and the problem of decomposition of PEO in the high-voltage battery can be fundamentally solved, so that the stable performance of the battery is improved.

Description

technical field [0001] The invention relates to the field of secondary lithium ion batteries, in particular to an in-situ preparation method and application of an amide-based composite solid electrolyte. Background technique [0002] With the continuous development of human society, the development of emerging renewable clean energy and the breakthrough of related technologies are particularly urgent today. In order to meet the needs of electric vehicles, portable electronic equipment, industrial production, aerospace, robotics and energy storage equipment Various energy conversion and storage technologies have been developed rapidly. Among various energy storage devices, lithium-ion batteries have the advantages of high energy density, long cycle life, high cycle efficiency, and fast charge and discharge. They are widely used in Portable electronics, electric vehicles and other large-scale energy storage facilities. At present, commercial lithium batteries mainly use organ...

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Problems solved by technology

For example, document 2: Zhao et al. ("Solid-state polymer electrolytes stabilized by task-specific saltadditives" [J]. JOURNAL OF MATERIALS CHEMISTRY.A, 2019.) added LiNO3 to the PEO polyelectrolyte LiNO3 produces a stable solid electrolyte interphase (SEI film) on the negative electrode, LiBOB produces a stable positive electrode electrolyte passivation layer (CEI film) on the surface of the positive electrode, and LiTFSI As a carrier fluid, the electrochemical stability of the composite solid electrolyte is as high as 4.6V, and its LiNi1 / 3Co1 / 3Mn1 / 3 sub>O2 / Li high-voltage solid-state battery at 60°C and 0.2C, the discharge capacity is only 100mAh / g after 60 cycles, and the rate is 0.1C, 0.2C, 0.3C and 0.5C. The discharge capacities are 133.6, 121.7, 115.2, and 100.9mAh / g, respectively. However, due to the low room temperature ionic conductivity of the PEO solid electrolyte, it cannot be used at room temperature or near room temperature. In addition, the elastic modulus of the electrolyte is only 0.332MPa.

[0005]Although the high-voltage stability of the positive electrode surface has been improved by the PEO-based solid electrolyte, by coating the high-voltage positive electrode material or adding lithium salt to the electrolyte, However, it cannot fundamentally solve the decomposition of the electrolyte under high voltage, and the disadvantages of poor electrolyte interface compatibility and low room temperature ionic conductivity restrict the large-scale application of solid-state batteries.