Lithium salt type liquid-free ion conductive elastomer and preparation method and application thereof

Abstract

The application relates to the field of high polymer materials, and particularly discloses a lithium salt type liquid-free ion conductive elastomer and a preparation method thereof, wherein the elastomer is obtained by polymerization of first monomers and second monomers, the first monomers are obtained by mixing lithium salt type hydrogen bond donors and acrylic acid, and the second monomers are obtained by mixing lithium salt type hydrogen bond donors and maleic acid. The liquid-free ion conductive elastomer provided in the application is prepared from lithium salt type polymerizable eutectic solvent monomers which have good performance in almost all aspects (optics, self-repair and electrical performance) after photopolymerization of two kinds of photoinitiators, the obtained LSEs can realize high conductivity (0.27-1.43 S / m), transparency (up to 92.1%), VOC pollution-free, self-repair (the self-repair efficiency can reach 92% at 70 DEG C for 48 h).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, in particular to a lithium salt type liquid-free ion conductive elastomer and a preparation method and application thereof. BACKGROUND

[0002] With the increasing demand for flexible electronic devices, research on flexible electronic devices has also increased exponentially in recent years. Huang Weizeng, an academician of the Chinese Academy of Sciences, mentioned that flexible electronic devices should develop in the direction of being people-oriented, more environmentally friendly in process, more widely applied, and more functional. Therefore, conductive elastomers are also expected to have multiple functional properties in one: green, easy to manufacture, high conductivity, self-healing performance, high transparency, etc. However, the current research on ion conductors still cannot meet the above requirements at the same time: the research on hydrogel ion conductors often faces the problems of low long-term stability, poor low-temperature resistance, and insufficient mechanical properties, and the liquid-free ion conductive elastomer will become a good substitute for hydrogel ion conductors due to its anti-freezing and anti-drying properties.

[0003] So far, the preparation methods of liquid-free ion conductors include the following three types.

[0004] The first type is to dissolve the salt and polymerizable monomer in an organic solvent (such as tetrahydrofuran (THF)), and finally evaporate the solvent and polymerize by light initiation to obtain a liquid-free ion conductive elastomer. For example, liu (Polymer 2022, 249, 124837.) manufactured a liquid-free ion conductive fluoride by dissolving monomers in THF, and the elastomer with a microphase separation structure produced an impressive room temperature ionic conductivity of 3.5×10 -3 S / m.

[0005] The second type is to introduce ions into the polymer through an ion exchange strategy, and finally evaporate the organic solvent to form a liquid-free ion conductor (for example, based on a rationally designed solid polyionic liquid-based copolymer, Sun (Materials Horizons 2020, 7, 2994-3004.) developed a self-healing and stretchable liquid-free ion conductive elastomer with an electrical conductivity of about 1.3×10 -2 S / m at room temperature).

[0006] The third type is to dissolve the salt in the liquid mixture formed by the polymerizable monomer, and the mixture is finally photopolymerized to form an ion conductive elastomer. For example, Ding (Nat Commun 2018, 9, 2630.) introduced a stretchable, transparent ion conductive elastomer with an electrical conductivity of 6.3×10 -7S / m. Jia (Adv Mater 2021, 33, e2006111.) demonstrated a liquid-free ionically conductive elastomer consisting of a cross-linked long-chain copolymer network and lithium salt (from 4.2 x 10 -4 ~5.2 x 10 -3 S / m). However, the above methods have several drawbacks. Most notably, the ionic conductivities of the prepared elastomers are generally low (<10 -2 S / m), while for liquid-free ionically conductive elastomers prepared by solvent evaporation, the evaporation of organic solvents leads to the release of volatile organic compounds (VOCs), which pollute the atmosphere. In addition, some liquid-free ionically conductive elastomers prepared by this method are opaque, limiting their application in the field of optoelectronics. Lithium salt elastomers, as a typical liquid-free ion conductor with lithium salt as a component, have attracted more and more attention due to their potential application in lithium ion battery electrolytes.

[0007] In summary, the existing high-performance ionically conductive elastomers are difficult to balance high ionic conductivity, high self-healing efficiency and high transparency. Therefore, it is necessary to develop a high-conductivity, transparent, stretchable and self-healing lithium salt type liquid-free ionically conductive elastomer to meet the development needs of new flexible devices. SUMMARY

[0008] The present application aims to overcome at least one of the above-mentioned deficiencies of the prior art and provide a lithium salt type liquid-free ionically conductive elastomer with high conductivity, transparency, stretchability and self-healing, as well as a preparation method and application thereof. Lithium salt elastomers, as a typical liquid-free ion conductor with lithium salt as a component, have attracted more and more attention due to their potential application in lithium ion battery electrolytes.

[0009] To achieve the above-mentioned purpose, the first aspect of the present application provides a lithium salt type liquid-free ionically conductive elastomer, which is obtained by polymerization of a first monomer and a second monomer, wherein the first monomer is obtained by mixing a lithium salt type hydrogen bond donor and acrylic acid; and the second monomer is obtained by mixing a lithium salt type hydrogen bond donor and maleic acid.

[0010] The present application uses two lithium salt type polymerizable deep eutectic solvent (Li-PDES) monomers as the two main monomers for synthesizing liquid-free lithium salt elastomers (LSEs) through structural design. The Li-PDES monomer with integrated structure is synthesized by a low eutectic strategy, and the Li-PDES monomer has good performance in optical, self-healing and electrical properties after photopolymerization. Compared with other lithium salt elastomer preparation strategies (such as salt dissolution in polymers), the present application is helpful for molecular level material design and microscopic adjustment of performance. In addition to the advantages of Li-PDES monomer polymers, fine structural design is also carried out according to the conductive mechanism of ion conductors to prepare high-conductivity LSEs.

[0011] According to any one of the embodiments of the first aspect of the application, the lithium salt type hydrogen bond donor is selected from at least one of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium (trifluoromethyl)(nonafluorobutyl)sulfonylimide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (LiFTFSI).

[0012] According to any one of the embodiments of the first aspect of the application, the first monomer is obtained by mixing lithium salt type hydrogen bond donor and acrylic acid at a molar ratio of 1:1.5-10; and the second monomer is obtained by mixing lithium salt type hydrogen bond donor and maleic acid at a molar ratio of 1:0.75-1.25. Preferably, the first monomer is obtained by mixing lithium salt type hydrogen bond donor and acrylic acid at a molar ratio of 1:2-4; and the second monomer is obtained by mixing lithium salt type hydrogen bond donor and maleic acid at a molar ratio of 1:1.

[0013] According to any one of the embodiments of the first aspect of the application, the first monomer and the second monomer are polymerized at a molar ratio of (0.1-10):1.

[0014] According to any one of the embodiments of the first aspect of the application, based on the total molar amount of the first monomer and the second monomer, the raw material of the elastomer further comprises 0.1-3% photoinitiator and 0.1-3% crosslinking agent.

[0015] According to any one of the embodiments of the first aspect of the application, the elastomer has an electrical conductivity of 0.27-1.43 S / m, a transparency of greater than 90%, and a self-repairing efficiency of 20%-92% at 70°C for 48h.

[0016] The second aspect of the application provides a preparation method of the above-mentioned liquid-free ion-conducting elastomer, comprising the following steps:

[0017] The first monomer and the second monomer are mixed to obtain a mixture;

[0018] The mixture is secondly mixed with a photoinitiator and a crosslinking agent to obtain the elastomer by photopolymerization.

[0019] According to any one of the embodiments of the second aspect of the application, the first mixing is specifically carried out at a mixing temperature of 80-100°C for a mixing time of 80-150 min.

[0020] The third aspect of the application provides application of the liquid-free ion-conducting elastomer in a flexible electronic device.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The lithium salt-type liquid-free ion-conductive elastomer provided in this application, through structural design, uses two lithium salt-type polymerizable eutectic solvent monomers that have good performance in almost all aspects (optical, self-healing and electrical properties) after photopolymerization to prepare LSEs. The obtained LSEs can simultaneously achieve high conductivity (0.27-1.43 S / m), transparency (transparency up to 92.1%), no pollution, and self-healing (self-healing efficiency can reach 92% at 70℃ for 48h). Attached Figure Description

[0022] Figure 1 A schematic diagram of the ultra-high ionic conductivity LSE prepared by utilizing the hydrogen and lithium bond interactions between LiTFSI and AA and MA molecules, and a comparison diagram of this application with recently reported lithium salt elastomers (see lower left corner).

[0023] Figure 2 The image shows the electrochemical impedance spectroscopy (EIS) spectra of the LSEs obtained in the examples.

[0024] Figure 3 This is a histogram of the conductivity of the LSEs obtained in the examples.

[0025] Figure 4 The graph shows the conductivity of the LSEs prepared in the examples as a function of temperature.

[0026] Figure 5 The resistance change of the LSEs (A0.5M1) prepared in Example 1 as a sensor under 25% strain for 45,000 seconds of cyclic stretching.

[0027] Figure 6 The graph shows the time and corresponding resistance changes of the LSEs prepared in Example 1 as writing pressure sensors.

[0028] Figure 7 The strain sensors of the elbow joint and the resistance response of the elbow joint during cyclic flexion are obtained by connecting the LSEs prepared in Example 1.

[0029] Figure 8 The strain sensors connected to the knee joint and the resistance response of the knee joint during cyclic flexion are shown for the LSEs prepared in Example 1.

[0030] Figure 9 The LSEs prepared in Example 1 are connected to strain sensors in the neck and the resistance response of the neck during cyclic flexion. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0032] For simplicity, only some numerical ranges are explicitly recited herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. Further, although a range is recited, it is to be understood that every point or individual number within the range is also specifically disclosed. Thus, every point or individual number can be combined with every other point or individual number to form a new range not explicitly recited.

[0033] In the description herein, it is to be understood that, unless otherwise specified, "above" and "below" are inclusive of the number, and "a plurality of" means two or more.

[0034] The foregoing summary of the present application is not intended to describe every disclosed embodiment or implementation of the present application. The following description more specifically illustrates example embodiments. Throughout this application, guidance is provided by a series of examples, which can be used in various combinations. In each instance, the recited list is merely representative of a non-exhaustive group, and should not be construed as exhaustive.

[0035] In the field of flexible electronics, the requirements for its process are increasingly green, widely applicable, and rich in functions, and therefore, the conductive elastomer is also expected to be able to integrate multiple functions in one: green, easy to manufacture, high conductivity, self-healing performance, high transparency, and the like. At present, liquid-free ion conductive elastomers are good substitutes for hydrogel ion conductors due to their anti-freezing and anti-drying properties, but the liquid-free ion conductive elastomers generally have relatively low conductivity (<10 -2 S / m), and the preparation process mostly involves the evaporation of organic solvents, causing the release of VOCs, polluting the environment, and the prepared ion conductive elastomers may also be opaque, not self-healing, and difficult to integrate multiple functions in one.

[0036] In view of the discovery and analysis of the above technical problems, in order to prepare liquid-free lithium salt elastomers (LSEs) with high conductivity, transparency, stretchability, and self-repairing, the present application is proposed.

[0037] The inventors have found that the liquid-free lithium salt elastomers (LSEs) obtained by polymerizing lithium salt type polymerizable deep eutectic solvent (Li-PDES) monomers with integrated structure have high conductivity, and also have the properties of transparency, stretchability, and self-repairing.

[0038] The first aspect of the embodiment of the present application provides a liquid-free ion-conductive elastomer, which is obtained by polymerization of a first monomer and a second monomer, wherein the first monomer is obtained by mixing a lithium salt type hydrogen bond donor and acrylic acid; and the second monomer is obtained by mixing a lithium salt type hydrogen bond donor and maleic acid.

[0039] Without being bound by any theory or explanation, the inventors have surprisingly found that using two lithium salt type polymerizable deep eutectic solvent (Li-PDES) monomers as two main monomers for synthesizing liquid-free lithium salt elastomers (LSEs), the Li-PDES monomers with integrated structures are synthesized by a eutectic strategy, and the Li-PDES monomers have good performance in optical, self-healing and electrical properties after photopolymerization. Compared with other lithium salt elastomer preparation strategies (e.g., salt dissolution in polymers), the present solution facilitates molecular-level material design and microscopic adjustment of performance, and in addition to the advantages of integrated Li-PDES monomers, fine structural design is also performed according to the conduction mechanism of ion conductors to prepare LSEs with high conductivity.

[0040] In some embodiments, the lithium salt type hydrogen bond donor is selected from at least one of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium (trifluoromethyl)(nonafluorobutyl)sulfonylimide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (LiFTFSI). The lithium salt type hydrogen bond donor has abundant hydrogen bond sites and lithium bond sites, and can form a polymerizable deep eutectic solvent with a hydrogen bond acceptor without introducing any organic solvent, which has good performance in mechanical, optical, self-healing and electrical properties, and can be used to subsequently prepare transparent, stretchable, self-repairing and highly conductive LSEs. Exemplarily, the lithium salt type hydrogen bond donor is lithium bis(trifluoromethylsulfonyl)imide (LiTFSI).

[0041] In the first monomer and the second monomer, the molar ratio of the lithium salt type hydrogen bond donor to acrylic acid and maleic acid is not particularly limited. In one example, the first monomer is obtained by mixing the lithium salt type hydrogen bond donor and acrylic acid at a molar ratio of 1:1.5-10; and the second monomer is obtained by mixing the lithium salt type hydrogen bond donor and maleic acid at a molar ratio of 1:0.75-1.25. Exemplarily, the first monomer is obtained by mixing the lithium salt type hydrogen bond donor and acrylic acid at a molar ratio of 1:2; and the second monomer is obtained by mixing the lithium salt type hydrogen bond donor and maleic acid at a molar ratio of 1:1. Exemplarily, the temperature for mixing the lithium salt type hydrogen bond donor and acrylic acid is 60-95°C, and the temperature for mixing the lithium salt type hydrogen bond donor and maleic acid is 60-95°C.

[0042] The preparation methods of the first monomer and the second monomer are only illustrative and do not limit the present application. In one example, to prepare high-conductivity, transparent, stretchable, self-healing liquid-lithium-salt-free elastomers (LSEs), the first monomer (Li-PDES monomer 1) and the second monomer (Li-PDES monomer 2) can be synthesized by the following method: LiTFSI and AA are mixed at a molar ratio of 1:2 and stirred at 90°C until a clear transparent mixture is obtained. At the same time, LiTFSI and MA are mixed at a molar ratio of 1:1 at 90°C and stirred until a clear transparent mixture is obtained, which is prepared as shown in Figure 1 This scheme is based on the rich hydrogen bonding sites and lithium bonding sites on LiTFSI, and a eutectic strategy is used to design lithium salt type polymerizable deep eutectic solvents (Li-PDES) monomers. Without introducing any organic solvent, Li-PDES monomers are formed by hydrogen bonding between lithium salt type hydrogen bond donors (Li-HBDs, such as LiTFSI) and polymerizable hydrogen bond acceptors (HBAs, such as AA and MA). In addition, the formation of hydrogen bonds leads to a decrease in the melting point of Li-PDES monomers.

[0043] In some embodiments, the first monomer and the second monomer are polymerized at a molar ratio of (0.1-10):1. For example, the molar ratio of the first monomer and the second monomer can be 0.1:1, 0.2:1, 0.3:1, 0.5:1, 0.7:1, 1:1, 1:0.9, 1:0.7, 1:0.5, 1:0.3, 1:0.1.

[0044] In some embodiments, based on the total molar amount of the first monomer and the second monomer, the raw materials of the elastomer further include 0.1-3% photoinitiator and 0.1-3% crosslinking agent.

[0045] The photoinitiator can be selected from one or more of benzoin and derivative photoinitiators, benzoin ether photoinitiators, alkylbenzophenone photoinitiators, acyl phosphine oxide photoinitiators. Specifically, the benzoin and derivative photoinitiator can be benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, etc. The benzoin ether initiator can be diphenyl ketone, α, α-dimethoxy-α-phenylacetophenone, etc. The alkylbenzophenone can be α, α-diethoxyacetophenone, α-hydroxyalkylbenzophenone, α-amine alkylbenzophenone, etc. The acyl phosphine oxide can be aryl acyl phosphine oxide, bisbenzoyl phenyl phosphine oxide, etc. More specifically, the photoinitiator can be one or more of 1173 (2-hydroxy-2-methyl-1-phenylpropanone), 184 (1-hydroxycyclohexyl phenyl ketone), TPO (diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide), TPO-L (2,4,6-trimethylbenzoyl phenyl phosphonic acid ethyl ester), 819DW (phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide), 2959 (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylpropanone).

[0046] The crosslinking agent can be selected from one or more of polyethylene glycol diacrylate, pentaerythritol tetraacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, divinylbenzene, N-hydroxymethyl acrylamide, diacetone acrylamide.

[0047] In some embodiments, the elastomer has an electrical conductivity of 0.27-1.43 S / m, a transparency of greater than 90%, and a self-repairing efficiency of 20%-92% at 70°C for 48h.

[0048] The second aspect of the present embodiment provides a method for preparing the above-mentioned liquid-free ion-conductive elastomer, comprising the following steps:

[0049] The first monomer and the second monomer are mixed to obtain a mixture;

[0050] The mixture is mixed with a photoinitiator and a crosslinking agent to obtain the elastomer through photopolymerization.

[0051] The inventors have found through repeated experiments that, compared with directly photopolymerizing all raw materials, the liquid-free ion-conductive elastomer obtained through photopolymerization has higher electrical conductivity and better tensile properties, by mixing the first monomer and the second monomer uniformly according to a certain molar ratio and then adding the crosslinking agent and the photoinitiator.

[0052] In some embodiments, the first mixing is specifically mixing at a temperature of 80-100°C for 80-150 min.

[0053] In some embodiments, the photo-induced polymerization is irradiating the second mixture with ultraviolet light for 0.5-10 min.

[0054] The third aspect of the present embodiment provides the application of the liquid-free ionically conductive elastomer in a flexible electronic device. Embodiment

[0055] The present disclosure is described in more detail by the following examples, which are merely illustrative and not limiting, as various modifications and changes in the aspects of the present disclosure will be obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used as received without further purification, and the instruments used in the examples are commercially available.

[0056] Example 1

[0057] A high-conductivity, transparent, stretchable, self-healing liquid-free lithium salt elastomer (LSEs), the specific preparation process and method are as shown in Figure 1 .

[0058] (1) Synthesis of Li-PDES monomer 1 and Li-PDES monomer 2: mix LiTFSI and AA at a molar ratio of 1:2 and stir at 90°C until a clear transparent mixture is obtained, which is Li-PDES monomer 1. At the same time, mix LiTFSI and MA at a molar ratio of 1:1 at 90°C until a clear transparent mixture is obtained, which is Li-PDES monomer 2.

[0059] (2) Mix the prepared Li-PDES monomer 1 and Li-PDES monomer 2 at a molar ratio of 0.5:1, and the solution obtained after mixing is called LiTFSI-AA-MA type Li-PDES monomer (Li-PDES monomer 3). Stir the prepared mixture uniformly, and add 0.2% crosslinking agent (PEGDA) and 0.2% photoinitiator (TPO) (based on the total molar amount of Li-PDES monomer 1 and Li-PDES monomer 2).

[0060] (3) Irradiate with ultraviolet light for 10 minutes to form LSEs.

[0061] The LSEs prepared in the present embodiment have a transparency of 92.1%, and a self-repairing efficiency of 91.02% at 70°C for 48h.

[0062] Example 2

[0063] The preparation process described in Example 1 was repeated, except that Li-PDES monomer 1 and Li-PDES monomer 2 were mixed at a molar ratio of 1:1.

[0064] The LSEs prepared in this example had a transparency of 91.3% and a self-repairing efficiency of 60.45% at 70°C for 48h.

[0065] Example 3

[0066] The preparation process described in Example 1 was repeated, except that Li-PDES monomer 1 and Li-PDES monomer 2 were mixed at a molar ratio of 1:0.5.

[0067] The LSEs prepared in this example had a transparency of 91.2% and a self-repairing efficiency of 40.32% at 70°C for 48h.

[0068] Example 4

[0069] The preparation process described in Example 1 was repeated, except that Li-PDES monomer 1 and Li-PDES monomer 2 were mixed at a molar ratio of 1:0.25.

[0070] The LSEs prepared in this example had a transparency of 90.9% and a self-repairing efficiency of 20.33% at 70°C for 48h.

[0071] Comparative Example 1

[0072] The preparation process described in Example 1 was repeated, except that step (1) only prepared Li-PDES monomer 1; and step (2) was specifically: 0.2% crosslinking agent (PEGDA) and 0.2% photoinitiator (TPO) were added to the prepared Li-PDES monomer 1 (based on the molar amount of Li-PDES monomer 1).

[0073] Comparative Example 2

[0074] The preparation process described in Example 1 was repeated, except that step (1) only prepared Li-PDES monomer 2; and step (2) was specifically: 0.2% crosslinking agent (PEGDA) and 0.2% photoinitiator (TPO) were added to the prepared Li-PDES monomer 2 (based on the molar amount of Li-PDES monomer 2).

[0075] Examples 1~4 were prepared according to different molar ratios of Li-PDES monomer 1 and Li-PDES monomer 2. Specifically, the molar ratios of Li-PDES monomer 1 and Li-PDES monomer 2 were 0.5:1, 1:1, 1:0.5, and 1:0.25, respectively. The LSEs prepared in each example were numbered according to the molar ratio of Li-PDES monomer 1 and Li-PDES monomer 2 mixed, for example: when Li-PDES monomer 1:Li-PDES monomer 2 = 1:0.25, the LSEs were numbered as A1M0.25.

[0076] Test Example

[0077] The electrical properties of the LSEs obtained in Examples 1~4 and their application in multifunctional sensors were tested, and the test results are shown in Figures 2-4 Figures 5-9 The sensor was prepared using the elastomer of Example 1 for testing. Among them, the material of Comparative Example 1 has a high hardness and low conductivity (only 4.3×10 -2 S / m) after polymerization, and Comparative Example 2 is very difficult to polymerize, so the electrical properties and their application in multifunctional sensors were not tested.

[0078] From Figure 2 and Figure 3 It can be seen that the electrical conductivity of the LSEs increases from 0.28 S / m (A1M0.25) to 1.43 S / m (A0.5M1) by electrochemical impedance spectroscopy. As the proportion of Li-PDES monomer 2 increases, the polymer chain segment becomes softer after photopolymerization, leading to easier coupling, Li + and TFSI - decoupling. Therefore, the ion movement is accelerated, leading to an increase in electrical conductivity.

[0079] In addition, as the temperature increases, the LSEs exhibit higher electrical conductivity (as shown in Figure 4 ). Among them, the electrical conductivity of the LSEs of A0.5M1 is 1.43 S / m at 30℃, and the electrical conductivity is 1.82 S / m at 90℃. The temperature-sensitive electrical conductivity can be explained as follows: the increase in temperature leads to more vigorous movement of the polymer chain segment, which is beneficial to ion transport, thereby leading to higher ionic conductivity. The relationship between the ionic conductivities of the LSEs conforms to the Arrhenius equation, indicating that the LSEs have a relatively stable electrical conductivity.

[0080] Figures 5-9 ​To further demonstrate the feasibility of the optically transparent, well-conducting, self-healing LSEs for electronic device applications, especially for some small deformation sensor signal detection, the LSEs prepared in Example 1 were used to fabricate a strain sensor to detect human motion. Meanwhile, the LSEs can also be used to detect a series of human motions.

[0081] Specifically, a strain sensor containing LSEs, a dielectric layer (3M tape) and a metal wire (the metal wire was connected to the LSEs) was fabricated by a sandwich structure (3M tape on both sides and LSEs in the middle). As shown in FIG. 11, the LSEs exhibited robust durability under 25% strain without severe fluctuation after 45000 seconds of cycling with a digital source meter. Randomly sampled signal tables indicated that the electrical signal was stable at the initial and final stages. As shown in FIG. 12, when the word "Peng" was written on the LSEs and repeated three times, the LSEs exhibited regular fluctuations in resistance each time the word was written. This means that the LSEs prepared in this example can be used as a writing pressure sensor. Figure 5 Figure 6 Figure 6 As shown in FIG. 13, the LSEs exhibited regular fluctuations in resistance each time the word was written, which means that the LSEs prepared in this example can be used as a writing pressure sensor.

[0082] Figures 7-9 Some data showing the application of the elastomer to different parts of the body are shown in FIGS. 14-17.

[0083] Figure 7 The application of the LSEs to the elbow is shown in FIG. 14: five consecutive bending experiments were performed, and the resistance changed by about 75% each time. This shows that the LSEs prepared in this example have stable resistance and have potential for sensor applications.

[0084] Figure 8 To apply the LSEs to the knee area, eight consecutive bending experiments were performed. The resistance changed by about 120% each time, showing good stability and indicating that it has good application prospects in motion detection.

[0085] Figure 9 The LSEs were placed on the neck, and the inventors found that the LSEs deformed at a specific resistance change by repeating "how are you" three times. Notably, the throat part caused by deformation was small, but the test equipment connected to the elastomer could still detect the resistance change, showing the relatively high sensitivity of the LSE sensor.

[0086] From the above tests, it can be seen that the LSEs prepared in Examples 1-4 have excellent electrical conductivity, high and relatively stable electrical conductivity, transparency and self-healing ability. At the same time, due to their sensitivity to small deformation, they can be applied to electronic devices, especially for some small deformation sensor signal detection.​​

[0087] Obviously, the above embodiments of the present application are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the specific embodiments of the present application. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A lithium salt type liquid-free ion conductive elastomer, characterized by, The elastomer is obtained by polymerization of a first monomer and a second monomer; wherein the first monomer is obtained by mixing lithium salt type hydrogen bond acceptor and acrylic acid; the second monomer is obtained by mixing lithium salt type hydrogen bond acceptor and maleic acid; The first monomer is obtained by mixing lithium salt type hydrogen bond acceptor and acrylic acid at a molar ratio of 1:1.5-10; the second monomer is obtained by mixing lithium salt type hydrogen bond acceptor and maleic acid at a molar ratio of 1:0.75-1.25; The first monomer and the second monomer are polymerized at a molar ratio of (0.5-1):1; The lithium salt type hydrogen bond acceptor is at least one selected from lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (trifluoromethyl)(nonafluorobutyl)sulfonylimide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide.

2. The lithium salt-type liquid-free ion conductive elastomer according to claim 1, characterized by, The raw material of the elastomer further comprises 0.1-3% photoinitiator and 0.1-3% crosslinking agent, based on the total amount of the first monomer and the second monomer.

3. A method for producing a liquid-free ionically conductive elastomer of a lithium salt type according to claim 1 or 2, characterized by, The method comprises the following steps: The first monomer and the second monomer are mixed to obtain a mixture; The mixture is mixed with a photoinitiator and a crosslinking agent to obtain the elastomer by photopolymerization.

4. The method for producing a lithium salt-type liquid-free ion conductive elastomer according to claim 3, characterized by, The first mixing is specifically carried out at a temperature of 80-100°C for 80-150 min.

5. Use of the lithium salt type liquid ion-conducting-free elastomer of claim 1 or 2 in a flexible electronic device.

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