Polyformaldehyde all-solid-state polymer electrolyte prepared by in-situ ring-opening polymerization and application thereof

Abstract

The invention relates to an all-solid-state polymer electrolyte, and particularly relates to a polyformaldehyde all-solid-state polymer electrolyte prepared by in-situ ring-opening polymerization andapplication of the polyformaldehyde all-solid-state polymer electrolyte in forming an all-solid-state secondary lithium battery. The all-solid-state polymer electrolyte is prepared by initiating in-situ ring opening polymerization of a trioxymethylene monomer, an additive and a lithium salt to a porous support material through a catalyst, wherein the thickness ranges from 10[mu]m to 800[mu]m; theroom-temperature ionic conductivity ranges from 4*10<-5>S/cm to 8*10<-3>S/cm, and the electrochemical window is not lower than 4.2V. The all-solid-state polymer electrolyte is easy to prepare and simple to form; the mechanical performance is excellent; and the room-temperature ionic conductivity is high. Meanwhile, the all-solid-state polymer electrolyte can effectively inhibit the growth of lithium dendrites and match with a high-voltage positive electrode material, so that the interface stability, the long cycle performance and the energy density are effectively improved.

Description

technical field [0001] The invention relates to an all-solid polymer electrolyte, in particular to a polyoxymethylene-based all-solid polymer electrolyte prepared by in-situ ring-opening polymerization and its application in forming an all-solid secondary lithium battery. Background technique [0002] Power lithium-ion batteries for electric vehicles, in addition to meeting the requirements of long mileage and high-power charging and discharging, safety performance is particularly important. At present, when commercial lithium-ion batteries based on liquid electrolytes are abused, short-circuited, or used in extreme conditions, a large amount of heat will be released inside the battery, which will ignite the organic electrolyte, causing safety hazards such as fire and explosion, which greatly threatens the safety and well-being of users. Experience, obviously difficult to use widely. Even the American Tesla car, which is currently considered the safest, uses a complex batte...

AI Technical Summary

Problems solved by technology

At present, when commercial lithium-ion batteries based on liquid electrolytes are abused, short-circuited, or used in extreme conditions, a large amount of heat will be released inside the battery, which will ignite the organic electrolyte, causing safety hazards such as fire and explosion, which greatly threatens the safety and well-being of users. experience, apparently difficult to use widely

Even the American Tesla car, which is currently considered the safest, uses a complex battery management system and protective measures, and there have been many fire and explosion accidents in just a few years after it came out.

In addition, there are still problems with organic electrolytes: limited electrochemical window, difficult to be compatible with metal lithium anodes and newly developed high-potential cathode materials; lithium ions are not the only carriers, and the internal resistance of the battery will be affected by the The appearance of the ion concentration gradient increases (concentration polarization), and the performance of the battery decreases; the working temperature is limited (the operating temperature is 0°C-40°C); it reacts with the negative electrode material to form a solid electrolyte interphase (SEI) layer, resulting in active lithium Continuous consumption, so that the battery capacity continues to decline

CN105826603 A describes an in-situ polymerized vinylene carbonate-based solid-state electrolyte system and its application, which has excellent mechanical properties, but the solid-state electrolyte has low room temperature ionic conductivity and cannot operate at room temperature

[0004] Polyethylene oxide (PEO) / lithium salt electrolytes have been used in solid-state lithium polymer batteries, but there are still some problems to be solved from the practical point of view: linear and grafted polymers have poor mechanical properties, and it is not easy to make independent Supported polymer film, while the conductivity of the network polymer is too small

Therefore, this kind of electrolyte system is only suitable for working under high temperature or low current conditions, and it is difficult to get practical application in lithium batteries working at normal temperature.

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