An intelligent lithium-ion battery gel electrolyte and a lithium battery

Abstract

The present invention relates to an intelligent lithium-ion battery gel electrolyte and a lithium battery. The gel electrolyte includes a gel and a lithium salt permeated and adsorbed in the gel. Among them, the gel is made by polymerizing at least one polymerizable monomer containing a carbon dioxide-adsorbing group, an unsaturated polymerizable zwitterionic monomer, a crosslinking agent, and an initiator in an organic solvent. In the gel electrolyte provided by the present invention, the group capable of adsorbing carbon dioxide reacts with the CO2 gas generated during the battery cycle, effectively reducing the risk of battery swelling. Secondly, the phase change generated by the zwitterion under thermal response can effectively inhibit the thermal runaway phenomenon of the battery. Moreover, the anion group in the zwitterion helps to regulate the growth of lithium dendrites. Therefore, this electrolyte integrates the advantages of alleviating battery swelling, regulating lithium dendrites, and phase change inhibiting thermal runaway, significantly improving the safety and electrochemical performance of lithium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and particularly to an intelligent lithium-ion battery gel electrolyte and a lithium battery. Background Art

[0002] Lithium-ion batteries have occupied a dominant position in applications such as mobile and portable devices, drones, electric vehicles, and large-scale energy storage power stations due to their significant advantages such as high energy density, long cycle life, high working voltage, low self-discharge rate, and no memory effect. However, currently, the mainstream commercial lithium-ion battery electrolytes usually use organic carbonate solvents. Under over-discharge or high-temperature environments, these organic solvents may undergo thermal decomposition, generating a large amount of gases such as CO2, resulting in an increase in the internal pressure of the battery, and increasing the risks of swelling and explosion. At the same time, under extreme conditions such as overcharge and over-discharge, lithium-ion batteries are prone to rapid thermal runaway, which may lead to serious accidents such as combustion or explosion. In addition, during the charge and discharge process of lithium-ion batteries, due to the uneven deposition of lithium ions, lithium dendrites may be formed. These dendrites may penetrate the battery separator, causing an internal short circuit of the battery, further increasing the safety hazard.

[0003] Currently, researchers have developed solid electrolytes represented by LLZO. The solid electrolytes do not contain flammable organic solvents and have good safety performance. However, due to their intrinsically large electrode / electrolyte interface impedance, these solid electrolytes have problems such as large internal impedance and low room-temperature conductivity of the battery, restricting their practical applications. In contrast, gel electrolytes, as an intermediate state between liquid and solid, have better electrode / electrolyte interface contact, higher room-temperature conductivity, and lower internal resistance compared to solid electrolytes. However, the gel electrolytes still contain flammable liquid electrolytes, which also means that there are still certain safety hazards.

[0004] Therefore, finding a gel electrolyte that has both high safety and high ionic conductivity remains a key challenge in current research. Summary of the Invention

[0005] In view of the above problems, there is provided an intelligent lithium-ion battery gel electrolyte and a lithium battery that have both high safety and high ionic conductivity.

[0006] The specific technical solutions are as follows:

[0007] The first aspect of the present invention is to provide an intelligent lithium-ion battery gel electrolyte, which includes a gel and a lithium salt permeating and adsorbed in the gel;

[0008] Among them, the gel is a gel prepared by a polymerization reaction of at least one polymerizable monomer containing a carbon dioxide-adsorbing group, an unsaturated polymerizable zwitterionic monomer, a cross-linking agent, and an initiator in an organic solvent.

[0009] Specifically, the group capable of adsorbing carbon dioxide is one of the amino groups (-NH2).

[0010] Specifically, the substance having an amino group (-NH2) is at least one of acrylamide, methacrylamide, and vinyl carbamate.

[0011] Specifically, the zwitterionic monomer is at least one of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, 2-methacryloyloxyethyl phosphorylcholine, and 1-propylsulfonic acid-3-vinylimidazolium inner salt.

[0012] Specifically, the initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, and cumene hydroperoxide.

[0013] Specifically, the crosslinking agent is at least one of polyethylene glycol diacrylate, ethylene glycol dimethacrylate, and triallyl isocyanurate.

[0014] Specifically, the organic solvent is at least one of dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, tetrahydrofuran, 1,3-dioxolane, diethyl carbonate / ethylene carbonate, ethylene glycol dimethyl ether / 1,3-dioxolane, and ionic liquid.

[0015] Specifically, the lithium salt is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, and lithium tetrafluoroborate.

[0016] The second aspect of the present invention is to provide a lithium battery including the above-mentioned intelligent lithium-ion battery gel electrolyte.

[0017] The beneficial effects of the above solution are as follows:

[0018] In the gel electrolyte provided by the present invention, the group capable of adsorbing carbon dioxide reacts with the CO2 gas generated during battery cycling, effectively reducing the risk of battery swelling; secondly, the phase change generated by the zwitterion under thermal response can effectively inhibit the thermal runaway phenomenon of the battery; furthermore, the anionic group in the zwitterion helps to regulate the growth of lithium dendrites. Therefore, this electrolyte integrates the advantages of alleviating battery swelling, regulating lithium dendrites, and phase change inhibiting thermal runaway, significantly improving the safety and electrochemical performance of lithium-ion batteries. Description of the Drawings

[0019] Figure 1 Schematic diagram of the absorption of CO2 molecules by the amino group in Example 1 of the present invention;

[0020] Figure 2 Step diagram of the free energy change after the amino group absorbs CO2 molecules in Example 1 of the present invention;

[0021] Figure 3 This is the schematic diagram of zwitterionic thermoresponsive phase transition in Embodiment 1 of the present invention. Detailed implementation manners

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0024] The present invention will be further described below with specific embodiments, but it is not limited to the present invention.

[0025] The present invention provides an intelligent lithium-ion battery gel electrolyte, which includes a gel and a lithium salt permeated and adsorbed in the gel; wherein, the gel is a gel prepared by a polymerization reaction of at least one polymerizable monomer containing a carbon dioxide adsorbing group, an unsaturated polymerizable zwitterionic monomer, a crosslinking agent, and an initiator in an organic solvent.

[0026] The present invention also provides a lithium battery including the above gel electrolyte, and its preparation method is as follows:

[0027] Add at least one polymerizable monomer containing a carbon dioxide adsorbing group and an unsaturated polymerizable zwitterionic monomer into an organic solvent according to a molar ratio of 1:(0.5 - 2);

[0028] Then, add an appropriate amount of lithium salt (lithium salt concentration is 0.5M - 1.5M), an initiator (the mass of the initiator is 2 - 5% of the total mass of the monomers), and a crosslinking agent (the mass of the crosslinking agent is 2 - 5% of the total mass of the monomers), and stir well to form a uniform monomer solution;

[0029] Drop the prepared monomer solution into a glass fiber separator to ensure that the solution can be evenly distributed in the separator, and then encapsulate to form a lithium battery;

[0030] Place the encapsulated battery in an oven at 60 - 70 °C for static placement for 12 - 24 h. After in-situ polymerization for a period of time, a lithium battery with a gel electrolyte is obtained.

[0031] Embodiment 1

[0032] In a 50 mL mixed solution of dimethyl carbonate and ethylene carbonate (volume ratio 1:1), 3.55 g of acrylamide and 13.97 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide were added;

[0033] 14.35 g of lithium bis(trifluoromethanesulfonyl)imide, 0.52 g of azobisisobutyronitrile and 0.52 g of polyethylene glycol diacrylate were added to this solution, and the mixture was stirred well until evenly mixed;

[0034] 1 mL of the mixed solution was dropped onto a glass fiber separator, and then a lithium battery was formed by encapsulation using a battery encapsulation machine (all experimental operations were carried out in a glove box with a water content below 0.1 ppm and an oxygen content below 0.1 ppm). The encapsulated battery was placed in an oven at 60 °C and left standing for 12 h.

[0035] Figure 1 The schematic diagram showing the absorption of CO2 molecules by amino groups is presented. First, acrylamide absorbs CO2 molecules, then a hydrogen atom on the amino group is protonated and migrates; finally, a coupling reaction occurs, resulting in amino acidification and the formation of amino acid groups.

[0036] Figure 2 The step diagram of the free energy change of the absorption of CO2 molecules by amino groups calculated by Gaussian is shown. The process of each stage corresponds to a specific energy value. Among them, the adsorption process of CO2 molecules is spontaneous.

[0037] Figure 3 The schematic diagram showing the thermoresponsive phase transition of zwitterions is presented. As the temperature rises, the hydrophobic solvent interaction between the main chain and the segments dominates, resulting in a phase transition in the gel electrolyte. The number of ions and electrons between the electrodes decreases, causing the battery reaction to cease and effectively preventing the temperature from rising further.

[0038] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all equivalent replacements and obvious changes made by using the content of the specification of the present invention should be included within the protection scope of the present invention.

Claims

1. An intelligent lithium-ion battery gel electrolyte, characterized in that, The gel electrolyte comprises a gel and a lithium salt permeating and adsorbed in the gel; Among them, the gel is a gel prepared by a polymerization reaction of at least one polymerizable monomer containing a carbon dioxide-adsorbing group, an unsaturated polymerizable zwitterionic monomer, a cross-linking agent, and an initiator in an organic solvent. The carbon dioxide-adsorbing group is an amino group, and the polymerizable monomer is at least one of acrylamide, methacrylamide, and vinyl carbamate; the zwitterionic monomer is at least one of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 2-methacryloyloxyethylphosphorylcholine, and 1-propylsulfonic acid-3-vinylimidazolium inner salt.

2. The intelligent lithium-ion battery gel electrolyte according to claim 1, wherein The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, and cumene hydroperoxide.

3. The intelligent lithium-ion battery gel electrolyte according to claim 1, wherein The cross-linking agent is at least one of polyethylene glycol diacrylate, ethylene glycol dimethacrylate, and triallyl isocyanurate.

4. The intelligent lithium-ion battery gel electrolyte according to claim 1, characterized in that, The organic solvent is at least one of dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, tetrahydrofuran, 1,3-dioxolane, diethyl carbonate / ethylene carbonate, ethylene glycol dimethyl ether / 1,3-dioxolane, and ionic liquid.

5. The intelligent lithium-ion battery gel electrolyte according to claim 1, wherein The lithium salt is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, and lithium tetrafluoroborate.

6. A lithium battery, characterized in that, The electrolyte in this lithium battery is the intelligent lithium-ion battery gel electrolyte described in any one of claims 1-5.

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