Polymer electrolyte capable of working in wide temperature range and preparation method thereof

Abstract

The invention discloses a polymer electrolyte capable of working in a wide temperature range, a preparation method of the polymer electrolyte and application of the polymer electrolyte in a solid-state lithium (sodium) secondary battery. The polymer electrolyte is prepared from a precursor solution containing a polymeric monomer, an initiator and an electrolyte salt on the surface of a base material in an in-situ polymerization manner, and is of a hyperbranched structure without a main chain and with multiple branched chains. The polymer electrolyte has the advantages of high ionic conductivity and transference number, wide electrochemical window, good mechanical strength and the like, and can stably work in a temperature range of -40-110 DEG C. Meanwhile, the preparation method of the polymer electrolyte is simple, mild in condition, low in preparation cost, easily available in raw materials and suitable for large-scale production. The polymer electrolyte disclosed by the invention isused for constructing a solid-state lithium (sodium) secondary battery, so that the working temperature of the battery can be effectively expanded, and the safety of the battery under extreme workingconditions is improved.

Description

technical field [0001] The invention belongs to the field of chemical power sources and also belongs to the technical field of energy materials, and specifically relates to a novel polymer electrolyte capable of working in a wide temperature range and a preparation method thereof. Background technique [0002] Compared with the organic liquid electrolytes commonly used commercially at present, the polymer electrolyte has the characteristics of no leakage, good safety performance, good electrochemical stability, and good mechanical properties, and it can also be prepared into any shape and size , making lithium-ion batteries develop in the direction of miniaturization and thinning. The original polymer electrolyte was the linear polymer PEO, a polymer consisting of one main chain -(CH2CH2O)n-. However, such a regular linear structure will make the molecular chains easy to entangle, and face the problems of crystallization at room temperature and low ionic conductivity. Ther...

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Problems solved by technology

The current common linear solid polymer electrolytes are limited by ionic conductivity, and are generally used at high temperatures (environment temperature higher than 40°C), and the polymers are in a fluid molten state at high temperatures, unable to maintain their original size, shape and mechanical properties. properties, making it difficult to inhibit dendrite nucleation / growth

Not only that, polymer electrolyte membranes are usually cast into membranes when assembling batteries, and the contact interface between the obtained electrodes and the electrolyte often has poor contact, resulting in a huge interface impedance, and a large amount of volatiles will be evaporated when casting the membrane. Solvents are wasted and pollute the environment

[0005] At present, the existing ionic conductivity can be modified by adding nano-inorganic fillers and ionic liquids. However, the technology of adding inorganic materials requires high selectivity for the size, type, and amount of nanoparticles, and has a negative effect on film-forming properties. , The strength has an uncertain effect. Ionic liquids have good conductivity. At present, there are studies using ionic liquids to improve the solubility of end groups. However, for the types of ionic liquids and hyperbranched polymers, the degree of ionization and the degree of hyperbranching There are technical difficulties in matching

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