A photo-patternable lithium-ion electrolyte and a preparation method and application thereof

Abstract

This invention discloses a photolithographically patternable lithium-ion electrolyte, its preparation method, and its applications. The electrolyte is a photolithographically curable lithium-ion electrolyte composition, comprising, by mass percentage, LiTFSI, polyethylene glycol methyl ether methacrylate, bisphenol A ethyl oxide dimethacrylate, fluoroethylene carbonate, succinic acid, 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP), 3-(isobutyryloxy)propyltrimethoxysilane, and 2-methyl-2-acrylate-2-hydroxyethyl. This invention also discloses a stepwise preparation method for this composition and its applications in micro-energy storage and ion-electronic devices such as micro solid-state batteries, ion-controlled transistors, and neuromorphic devices. This electrolyte can be patterned at the micro-nano scale using standard photolithography processes, exhibiting excellent lithium-ion conductivity, electrochemical stability, mechanical flexibility, and optical transparency. It also shows good interface compatibility with gold electrodes / silicon wafers, requiring no additional etching or transfer processes. This solves the technical problems of existing solid-state electrolytes being difficult to fabricate at the micro-nano scale and incompatible with microelectronic processes, and has broad application prospects in the fields of micro-nano fabrication and micro-devices.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte and micro / nano fabrication technology, specifically relating to a photolithographically patternable lithium-ion electrolyte, its preparation method, and its application. Background Technology

[0002] With the rapid development of microelectronics, microelectromechanical systems and on-chip integrated systems, the demand for micro energy storage devices and ion control devices in integrated circuits, flexible electronics and wearable systems is increasing, which puts forward higher requirements for the performance and processing technology of electrolyte materials.

[0003] Existing lithium-ion battery electrolytes are mainly divided into two categories: liquid organic electrolytes and solid electrolytes. While liquid organic electrolytes possess high ionic conductivity, they pose safety hazards such as leakage and flammability, and exhibit poor stability at the electrode interface, failing to meet the requirements for micro-device applications. Solid lithium-ion electrolytes, due to their leak-free nature, high safety, and excellent electrochemical stability, have become important functional materials for constructing micro solid-state batteries, ion transistors, and neuromorphic devices. However, existing lithium-ion solid electrolytes are mostly ceramic or gel / polymer materials. These materials are primarily suitable for macroscopic battery structures and are typically prepared using methods such as blade coating, pressing, or drop coating, making it difficult to achieve micro / nano-scale patterning, which greatly limits their application in on-chip micro-devices.

[0004] On the other hand, existing photoresist materials possess excellent lithographic resolution and micro / nano fabrication capabilities, making them commonly used materials in the field of micro / nano fabrication. However, they lack lithium-ion conductivity and cannot be directly used as solid-state electrolytes. If materials with both ion conductivity and lithographic properties are prepared by combining traditional solid-state electrolytes with photoresists, complex etching or transfer processes are typically required. This not only results in cumbersome processes and high processing costs but also easily introduces defects at the material interface, severely impacting the final performance of the device.

[0005] In summary, there is a lack of solid electrolyte materials in the current technology that can be patterned using standard photolithography processes while maintaining good lithium-ion conductivity, structural stability, and interface compatibility with electrodes. Developing such novel materials is of great significance for promoting the development of micro energy storage devices and ion electronic devices. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a photolithographically patternable lithium-ion electrolyte, its preparation method, and its application. This invention solves the technical problems of existing solid electrolytes being difficult to fabricate in micro-nano dimensions, incompatible with microelectronic processes, and unable to simultaneously meet the requirements of micro-devices for photolithographically patternable electrolytes, high ionic conductivity, and interface stability with gold electrodes / materials. This expands the application scope of solid electrolytes in micro energy storage devices and ion electronic devices.

[0007] To achieve the above objectives, the present invention provides a photolithographically patternable lithium-ion electrolyte, which is a photolithographically curable lithium-ion electrolyte composition, comprising the following components by weight percentage: lithium salt LiTFSI 5-10 wt%; solvent polyethylene glycol methyl ether methacrylate 20-30 wt% and bisphenol A ethyl oxide dimethacrylate 40-60 wt%; conductivity additive fluoroethylene carbonate 4-6 wt% and succinic anionizer 0.5-1 wt%; photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone 1-3 wt%; silicon wafer-electrolyte interface improver 3-(isobutyryloxy)propyltrimethoxysilane 0.5-1.5 wt% and 2-methyl-2-acrylate-2-hydroxyethyl 0.5-1.5 wt%.

[0008] Furthermore, the molecular weight of the polyethylene glycol methyl ether methacrylate is 473, and the molecular weight of the bisphenol A ethyl oxide dimethacrylate is 1700; the photoinitiator initiates cross-linking and curing of the polymer matrix under ultraviolet light, so that the exposed area forms a cured structure that is insoluble in the developer, and the unexposed area can be removed by the developer to obtain a preset patterned electrolyte structure.

[0009] The present invention also provides a method for preparing a photolithographically patternable lithium-ion electrolyte as described above, comprising the following steps: (1) Mix lithium salt LiTFSI, polyethylene glycol methyl ether methacrylate and bisphenol A ethyl oxide dimethacrylate in proportion, heat and stir evenly in the inert atmosphere of the glove box until the lithium salt is completely dissolved. (2) Add fluoroethylene carbonate and succinate to the mixed solution in step (1), and continue heating and stirring until homogeneous under the inert atmosphere; (3) Cool the solution from step (2) to room temperature, add 3-(isobutyryloxy)propyltrimethoxysilane, 2-methyl-2-acrylic acid-2-hydroxyethyl and 2-hydroxy-2-methyl-1-phenyl-1-propanone, stir until uniform, and obtain a photolithographically patternable lithium-ion electrolyte solution.

[0010] Furthermore, the inert atmosphere described in steps (1) and (2) is an Ar atmosphere, and the water oxygen content in the atmosphere is <1ppm.

[0011] Furthermore, the heating temperature in step (1) is 50-80℃, the stirring speed is 200-400r / min, and the stirring time is 1-5h; the heating temperature in step (2) is 50-80℃, the stirring speed is 200-400r / min, and the stirring time is 10-60min; the stirring time in step (3) is 1-3h.

[0012] Furthermore, the process also includes an electrolyte film preparation step: the obtained photolithographically patternable lithium-ion electrolyte solution is dropped onto the cleaned SiO2 / Si substrate surface, and a film is formed by spin coating. The spin coating parameters are 400-600 r / min for 5-15 s, followed by 3000-5000 r / min for 30-60 s.

[0013] Furthermore, it also includes a photolithography patterning step: the sample after spin coating is placed in an ultraviolet lithography machine for exposure treatment, then the sample is placed in PEGMA developer to develop, remove the unexposed areas, and then the sample is rinsed with isopropanol and dried with nitrogen to obtain a patterned lithium-ion electrolyte structure.

[0014] Furthermore, the exposure processing parameters are: exposure wavelength 385 nm, exposure time 1 min, and exposure dose 160 mJ / cm². 2 The development time is 60 seconds.

[0015] The present invention also provides an application of the photolithographically patternable lithium-ion electrolyte as described above, which is used in the fabrication of micro solid-state batteries, ion-controlled transistors, neuromorphic devices, or in the fabrication of micro energy storage devices and micro / nano ion electronic devices in the fields of integrated circuits and flexible electronics.

[0016] The beneficial effects of this invention are: The lithium-ion polymer electrolyte of this invention possesses excellent photolithographic patterning capabilities, enabling precise fabrication of micro-nano scale structures through standard photolithography processes. It is highly compatible with microelectronic processes, solving the technical challenge of micro-nano fabrication of existing solid-state electrolytes. The material of this invention combines good lithium-ion conductivity with negative photolithography properties, allowing it to be directly used as a patterned ion-conducting medium without additional etching or transfer processes. This simplifies the fabrication process of micro-devices, reduces processing costs, and avoids interface defects introduced by additional processes. The electrolyte of this invention exhibits good mechanical flexibility, making it suitable for flexible two-dimensional material devices and expanding its applications in flexible electronics, wearable devices, and other fields. The electrolyte of this invention also possesses good optical transparency, facilitating in-situ optical testing of devices and making it suitable for the fabrication and application of various optoelectronic devices. By adding a dedicated interface modifier, this invention optimizes the interfacial bonding performance between the electrolyte and the silicon wafer and gold electrode, ensuring the structural stability and electrochemical performance of the device. Attached Figure Description

[0017] Figure 1 Multi-scan rate CV plots for gold|electrolyte|gold symmetric devices are used to characterize the electrochemical stability and ion transport behavior of the electrolyte; Figure 2 EIS test results for gold-electrolyte-gold symmetric devices are used to analyze the ion conduction characteristics of the electrolyte and calculate the ion conductivity. Figure 3 These are optical microscope images of gold-electrolyte-gold symmetric devices, used to observe the micro / nano structure morphology formed by patterned electrolytes and gold electrodes. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0019] (1) Preparation of lithium-ion polymer electrolyte solution 2.63 g of polyethylene glycol methyl ether methacrylate was weighed as solvent A, and 6.42 g of bisphenol A ethyl oxide dimethacrylate was added as solvent B. The mixture was magnetically stirred at room temperature for 30 min until completely homogeneous. Then, 0.8 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added, and the mixture was magnetically stirred at 300 r / min for 2 h at approximately 60 °C to fully dissolve the lithium salt and form a homogeneous, transparent solution. Next, 0.56 g of fluoroethylene carbonate and 0.084 g of succinic anionyl were added, and the mixture was stirred at 300 r / min for another 30 min at 60 °C. Finally, the solution was cooled to room temperature, and 0.112 g of 3-(isobutyryloxy)propyltrimethoxysilane, 0.112 g of 2-methyl-2-acrylate-2-hydroxyethyl, and 0.224 g of photoinitiator were added, and the mixture was stirred for 1.5 h to obtain a photolithographically patternable lithium-ion polymer electrolyte solution.

[0020] (2) Preparation of electrolyte thin film The electrolyte solution was dropped onto the cleaned SiO2 / Si substrate surface and a film was formed by spin coating. The spin coating parameters were 500 r / min for 10 s, followed by 4000 r / min for 40 s.

[0021] (3) Photolithographic patterning The sample was exposed to ultraviolet light using a UV lithography machine at a wavelength of 385 nm for 1 min, with a dose of approximately 160 mJ / cm². 2 The surface was then developed in PEGMA developer for 60 seconds to remove unexposed areas. It was then rinsed with isopropanol and dried with nitrogen to obtain a patterned lithium-ion electrolyte structure.

[0022] (4) Cyclic voltammetry test Cyclic voltammetry (CV) tests were performed on the Au / electrolyte / Au structure using an electrochemical workstation. The test voltage range was -4 V to 0 V, and the scan rate was 1–50 mV·s. -1 The test results showed that no obvious redox peaks were observed within the measured voltage range, indicating that the electrolyte has good electrochemical stability within this range. With increasing scan rate, the current response gradually increased, indicating that the device exhibits typical capacitive ion transport behavior. These results demonstrate that the prepared lithium-ion polymer electrolyte possesses stable ion migration capabilities.

[0023] (5) AC impedance test Electrochemical impedance spectroscopy (EIS) was performed on the device using an electrochemical workstation. The resulting Nyquist plot consisted of a semicircle in the high-frequency region and a sloping straight line in the low-frequency region, indicating that the device possesses ion conduction characteristics. The impedance spectrum was fitted using an equivalent circuit R1-(R2‖CPE). The electrolyte resistance Rb was obtained from the Nyquist plot. Combined with the electrolyte thickness L and electrode area A, the ionic conductivity was calculated using the formula σ = L / (Rb×A). The calculation results show that the conductivity is approximately 4.17 × 10⁻⁴ s·cm. -1 The prepared lithium-ion polymer electrolyte exhibits ionic conductivity at room temperature, making it suitable for ion transport and micro-battery applications.

[0024] This embodiment demonstrates that the photolithography-based lithium-ion polymer electrolyte can form a stable pattern through standard photolithography processes and exhibits good electrochemical stability and ion conduction characteristics in the Au / electrolyte / Au structure, making it suitable for micro energy storage devices and micro / nano ion device applications.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photolithographically patternable lithium-ion electrolyte, characterized in that, The composition is a photolithographically curable lithium-ion electrolyte composition, comprising the following components by weight percentage: lithium salt LiTFSI 5-10 wt%; solvent polyethylene glycol methyl ether methacrylate 20-30 wt% and bisphenol A ethyl oxide dimethacrylate 40-60 wt%; conductivity additive fluoroethylene carbonate 4-6 wt% and succinic anion 0.5-1 wt%; photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone 1-3 wt%; silicon wafer-electrolyte interface improver 3-(isobutyryloxy)propyltrimethoxysilane 0.5-1.5 wt% and 2-methyl-2-acrylate-2-hydroxyethyl 0.5-1.5 wt%.

2. The photolithographically patternable lithium-ion electrolyte according to claim 1, characterized in that, The molecular weight of the polyethylene glycol methyl ether methacrylate is 473, and the molecular weight of the bisphenol A ethyl oxide dimethacrylate is 1700. The photoinitiator initiates cross-linking and curing of the polymer matrix under ultraviolet light, so that the exposed area forms a cured structure that is insoluble in the developer, and the unexposed area can be removed by the developer to obtain a preset patterned electrolyte structure.

3. A method for preparing a photolithographically patternable lithium-ion electrolyte as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Mix lithium salt LiTFSI, polyethylene glycol methyl ether methacrylate and bisphenol A ethyl oxide dimethacrylate in proportion, heat and stir evenly in the inert atmosphere of the glove box until the lithium salt is completely dissolved. (2) Add fluoroethylene carbonate and succinate to the mixed solution in step (1), and continue heating and stirring until homogeneous under the inert atmosphere; (3) Cool the solution from step (2) to room temperature, add 3-(isobutyryloxy)propyltrimethoxysilane, 2-methyl-2-acrylic acid-2-hydroxyethyl and 2-hydroxy-2-methyl-1-phenyl-1-propanone, stir until uniform, and obtain a photolithographically patternable lithium-ion electrolyte solution.

4. The method for preparing a photolithographically patternable lithium-ion electrolyte according to claim 3, characterized in that, The inert atmosphere described in steps (1) and (2) is an Ar atmosphere, and the water oxygen content in the atmosphere is < 1 ppm.

5. The method for preparing a photolithographically patternable lithium-ion electrolyte according to claim 3, characterized in that, The heating temperature in step (1) is 50-80℃, the stirring speed is 200-400r / min, and the stirring time is 1-5h; the heating temperature in step (2) is 50-80℃, the stirring speed is 200-400r / min, and the stirring time is 10-60min; the stirring time in step (3) is 1-3h.

6. The method for preparing a photolithographically patternable lithium-ion electrolyte according to claim 3, characterized in that, It also includes an electrolyte film preparation step: the obtained photolithographically patternable lithium-ion electrolyte solution is dropped onto the cleaned SiO2 / Si substrate surface, and a film is formed by spin coating. The spin coating parameters are 400-600 r / min for 5-15 s, followed by 3000-5000 r / min for 30-60 s.

7. The method for preparing a photolithographically patternable lithium-ion electrolyte according to claim 6, characterized in that, It also includes a photolithography patterning step: the sample after spin coating is placed in an ultraviolet lithography machine for exposure treatment, then the sample is placed in PEGMA developer to develop, remove the unexposed areas, and then the sample is rinsed with isopropanol and dried with nitrogen to obtain a patterned lithium-ion electrolyte structure.

8. The method for preparing a photolithographically patternable lithium-ion electrolyte according to claim 7, characterized in that, The exposure processing parameters are: exposure wavelength 385 nm, exposure time 1 min, and exposure dose 160 mJ / cm². 2 The development time is 60 seconds.

9. An application of the photolithographically patternable lithium-ion electrolyte as described in claim 1 or 2, characterized in that, The electrolyte can be applied to the fabrication of micro solid-state batteries, ion-controlled transistors, and neuromorphic devices, or to the fabrication of micro energy storage devices and micro / nano ion electronic devices in the fields of integrated circuits and flexible electronics.

Images