Polymer electrolyte and preparation method and application thereof

Abstract

The invention discloses a polymer electrolyte and a preparation method and application thereof. The polymer electrolyte comprises a polymer matrix, the polymer matrix is a polymer formed by self-polymerization of a polymeric monomer composed of three building blocks of acryloyl, carbamate and phosphate, or a polymer formed by copolymerizing a polymeric monomer and other monomers, wherein the polymeric monomer is composed of three building blocks, namely acryloyl, carbamate and phosphate. The polymer electrolyte can be used in a battery, the polymer matrix can be subjected to a self-crosslinking reaction at a high temperature of 130-190 DEG C to generate a compact thermosetting polymer which can cut off ion transmission and prevent thermal runaway of the battery; the self-crosslinking reaction is an endothermic reaction, so that the temperature of the battery can be quickly reduced, and the thermal runaway of the battery can be prevented; the polymer electrolyte can capture free radicals and has intrinsic flame retardance; and the characteristics of the polymer matrix are synergistic, so that the thermal runaway of the battery can be effectively prevented.

Description

technical field [0001] The invention relates to the technical field of battery electrolytes, in particular to a polymer electrolyte and its preparation method and application. Background technique [0002] Secondary lithium-ion batteries have the advantages of high energy density, long cycle life, and no memory effect, and have been widely used in 3C electronic products, electric vehicles and other fields. However, currently commercialized lithium batteries often use volatile and flammable organic carbonate-based liquid electrolytes, which can easily lead to safety hazards such as fire and explosion. In order to improve the safety of batteries, researchers have proposed a series of optimization measures, including changing the electrolyte solvent, designing high-concentration salt electrolytes, and using inorganic solid electrolytes or polymer electrolytes. Among them, the use of polymer electrolytes instead of liquid electrolytes is an effective method. Compared with the ...

AI Technical Summary

Problems solved by technology

As mentioned above, although these polyphosphate-based electrolytes are flame retardant, they still cannot completely avoid the occurrence of thermal runaway of high-energy-density lithium batteries under abusive conditions (such as short circuit, extrusion, needle sticking, etc.)

For example, CN107863555B and CN107819151B respectively disclose a non-combustible solid electrolyte containing polyphosphate polymer and composite solid electrolyte, but the polymer electrolyte does not have the ability of secondary cross-linking at high temperature, so it is difficult to reduce the high-energy lithium battery (such as NCM811 / Li metal battery) the risk of thermal runaway due to short circuit under acupuncture and extrusion conditions; A non-flammable polymer electrolyte prepared by in-situ curing of the electrolyte precursor solution, but the electrolyte has a low room temperature ionic conductivity (1.3×10-4~4.5×10-4Scm-1) and a narrow potential window (4~5V ), it is difficult to meet the needs of high energy density lithium batteries

Moreover, this method of preparing polymer electrolytes by ring-opening polymerization of terminal epoxy groups in situ suffers from the drawbacks of low molecular weight and low monomer conversion

Furthermore, although this polymer electrolyte improves the flame retardancy of the battery to a certain extent, it does not have the ability of secondary crosslinking at high temperature to cause the battery to self-shut down; CN111499873A discloses a polyphosphoric acid-based polymer and its preparation method and application

Although the polymer-based electrolyte has a certain flame retardancy, it also does not have the ability of high-temperature secondary crosslinking to cause battery self-shutdown at high temperatures, so it cannot meet the safety requirements of high specific energy lithium batteries; CN111620974A discloses a A phosphorus-containing polyester electrolyte for high-voltage lithium-ion batteries, but its polymer matrix does not have the reactivity of high-temperature secondary crosslinking to cause battery self-shutdown, so it cannot ensure the safety of batteries under abuse conditions; CN110247111A and CN111253523A In situ polymerizable polyphosphate-based polymer electrolytes were disclosed

Although these two electrolytes are non-flammable and have excellent electrochemical properties, they also do not have the ability to self-shutdown the battery due to secondary cross-linking at high temperatures, so they cannot meet the safety requirements of the battery under abuse conditions.

Images