Composite Electrode, Stretchable Battery, and Method Thereof

Abstract

The present disclosure relates to a composite electrode comprising a polymer containing carbon particles infiltrated by gallium or a gallium-indium alloy, a cathode electrode comprising silver oxide and a styrene-isoprene block copolymer (Ag 2 O-SIS) and a cathode current collector, and an anode electrode comprising gallium, carbon and a polymer and an anode current collector, a stretchable battery, wherein each of the cathode current collector and the anode current collector comprises a first current collector made of a composite material containing liquid metal eutectic gallium-indium (EGaIn), silver (Ag) and a styrene-isoprene block copolymer (SIS), and a second current collector layer made of carbon black (CB) and a styrene-isoprene block copolymer (SIS). The present disclosure also relates to a method for obtaining a composite electrode and a stretchable battery.

Description

Technical Field

[0001] The present disclosure relates to a composite electrode, a stretchable battery, a method for obtaining an electrode, and a method for obtaining the stretchable battery.

Background Art

[0002] Next-generation stretchable and soft electronics are expected to have an innovative impact in various application fields including health monitoring [1-5], robotics [6-8], e-textiles [9], flexible displays

[10] , and structural electronics [11, 12]. These circuits are fabricated by screen printing, laser patterning

[17] , and direct printing [16, 18] using conductive composite materials

[13] , deterministic or serpentine structures [14, 15], and liquid metals

[16] . Applications to wearable electromyography (EMG)

[19] , electrocardiography (ECG)

[20] , and electroencephalogram (EEG)

[21] have been demonstrated. However, most past implementations are connected to an external power source or use a battery, which is the bulkiest and most rigid component within the patch. In recent years, several solutions for energy harvesting for biomedical applications have been studied. These include flexible solar cells [22, 23], microbial fuel cells

[24] , and piezoelectric nanogenerators [25, 26]. These are typically used in combination with supercapacitors for storage [27, 28]. However, printed batteries have an areal capacitance that is at least 10 times higher than other thin-film energy harvesting / storage solutions but have a tenth of the areal power density compared to rigid coin cell batteries. This indicates both the potential of printed batteries for next-generation unconnected biomonitoring patches, e-textiles, and other IoT devices and the importance of further research.

[0003] In recent years, research on printable batteries has targeted novel architectures

[29] , as well as materials for current collectors

[30] , electrodes

[31] , and electrolytes

[32] . A variety of fabrication mechanisms such as screen printing and stencil printing

[33] , laser patterning

[34] , and spray coating

[35] have also been the subject of numerous studies, resulting in the demonstration of flexible [32, 36-39] and stretchable [32-35] thin film

[43] batteries.

[0004] A series of batteries that are more frequently used in miniaturized devices are silver oxide-zinc (Ag 2 O-Zn) batteries, which are used in hearing aids, smartwatches, and glucose monitors. This is mainly due to their higher power density

[36] , lower self-discharge rate, and lower flammability compared to lithium-ion batteries [32, 37]. Last year, the inventors provided a thin film sticker [3] with a printed Ag -2 O-Zn battery on a thin tattoo paper (about 5 μm) that achieved a maximum capacity of 5.10 mAh cm 2 . In a recent research document

[44] , an areal capacity of 12.5 mAh cm -2 was obtained with a thick multilayer electrode structure, but stretchability was not demonstrated.

[0005] Despite these promising results, current techniques for fabricating stretchable batteries involve numerous manual steps and are not yet autonomous and scalable. There is growing interest in rapidly fabricating customized advanced electronic devices, IoT stickers, e-textiles, and patches for biomonitoring by digital printing. Digital printing eliminates the need for stencil fabrication and manual deposition and enables autonomous fabrication of customized systems.

[0006] The use of gallium as an anode was described 30 years ago in a patent

[45] (see US Patent Application Publication No. 5,462,821) for the redox reaction Ga - 3e 3- + 6OH -⇔GaO3 3- +3H 2 O (FIG. 1B) has already been proposed. Gallium presents interesting properties that have recently been studied in batteries

[46] . The self-healing ability of gallium has already been applied to improve cycle stability in lithium batteries (LiB) [47, 48]. Furthermore, the high theoretical capacity of gallium has attracted the use of gallium-based anodes in batteries [49-51]. However, the above recent studies on Ga-based batteries have focused on conventional rigid batteries using bulk metal electrodes.

[0007] U.S. Patent Application Publication No. 2021119213 discloses an electrode useful for an electrochemical cell. The electrode includes an electrochemically active material, a conductive material, a solid ion-conductive polymer electrolyte, and a binder, and the binder is dispersed in an aqueous solution. U.S. Patent Application Publication No. 2021119213 also discloses a method of manufacturing a battery including the electrode.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] Despite the rapid progress of stretchable and flexible batteries, current manufacturing methods involve manual displacement and stencil / screen printing.

[0010] The above matters are disclosed to explain the technical problems to be addressed by the present disclosure.

Means for Solving the Problems

[0011] The present disclosure provides a digitally printable and stretchable gallium-based composite material including a printable gallium-carbon-SIS material as an anode electrode. SIS represents a styrene-isoprene block copolymer.

[0012] For the first time, the present disclosure introduces a 3D printable Ag-Ga (silver-gallium) battery by later printing four printable and sinter-free composite materials: a stretchable liquid metal EGaIn-Ag-SIS (eutectic gallium-indium-silver-styrene-isoprene block copolymer) current collector, a carbon-SIS (carbon-styrene-isoprene block copolymer) current collector, an Ag 2 O-SIS (silver oxide-styrene-isoprene block copolymer) cathode, and a novel Ga-C-SIS anode (gallium-carbon-styrene-isoprene block copolymer). Being sinter-free brings faster printing and compatibility with heat-sensitive substrates. Ga-C-SIS is solid and does not bleed after printing, but generates a liquid interface after contact with the electrolyte. As a result, a self-supplying and self-aggregating mechanism is brought about that transports more gallium to the surface and delays the formation of a wasteful surface. With a record area capacity of approximately 19.4 mAh cm -2 and excellent stretchability (strains of over 130% maximum), the Ag-Ga (silver-gallium) battery is an excellent alternative to Ag-Zn (silver-zinc) batteries. In one embodiment, an Ag electrode three times larger in area than the gallium electrode is fabricated, and the area capacity per 1 cm -2 of the gallium electrode was over 60 mAh. This is because the theoretical capacity of Ag is lower than that of Ga, and the optimal ratio of the areas of the gallium and silver electrodes is in the range of 3:1 to 4:1.

[0013] In one embodiment, surprisingly, digital printing results in a three - fold higher areal capacity compared to stencil printing by exposing more gallium on the surface. By digitally printing several battery cells and interconnects, the connection of the cells can be customized in series / parallel for desired voltage and current output. This is also demonstrated for the printing of sensors, electrodes, batteries, and interconnects onto e - textile for biomonitoring for simultaneous monitoring of ECG, body temperature, and respiration.

[0014] The present disclosure relates to a composite electrode comprising a polymer containing carbon particles infiltrated by gallium or a gallium - indium alloy.

[0015] In one embodiment, the carbon:gallium ratio in the polymer is 0.5% - 20%, preferably 1% - 5% for infiltration between galliums.

[0016] In one embodiment, gallium is in the form of micro - droplets in the range of 0.1 μm - 1000 μm.

[0017] Preferably, the electrode is conductive after deposition without the need for thermal sintering. Preferably, the viscosity is adjusted by adding a solvent to the polymer to make it printable by digital printing, screen printing, extrusion printing, or stencil printing.

[0018] Preferably, the anode electrode comprises a gallium - carbon - polymer composite material containing gallium particles embedded in the polymer, further comprising carbon particles infiltrating between the gallium particles to provide a non - sintered type electrode. Gallium can be mixed with other components in a liquid state when superheated above 30 °C, preferably 50 °C. Preferably, the mixing of gallium, carbon, and elastomer is performed by shear mixing, planetary mixing, ultrasonic - assisted mixing, or their equivalents.

[0019] In one embodiment, the carbon:gallium ratio in the polymer is 0.5% to 20%, preferably 1% to 5%.

[0020] In one embodiment, the polymer is selected from the group consisting of silicone, polyurethane, styrene block copolymer, or mixtures thereof.

[0021] In one embodiment, the amount of the polymer is 2 to 20 wt%, preferably 4 to 9 wt%, based on the composite material.

[0022] In one embodiment, the polymer is a styrene-isoprene-styrene block copolymer.

[0023] Preferably, the polymer is soluble in a solvent.

[0024] Preferably, the percentage of the solvent is adjusted to adjust the viscosity of the composite material such that the composite material can be printed by a preferred deposition method selected from rod coating, slot die coating, digital printing, screen printing, stencil printing, gravure printing, or equivalents thereof.

[0025] Preferably, the polymer is a stretchable elastomer that provides a stretchable electrode, and the polymer is reversible, which means that the polymer can be reversibly changed to a gel or a solid by exposure to a solvent.

[0026] In one embodiment, the carbon is in the form of nanoparticles or microparticles and is selected from carbon black, carbon nanowire, graphene quantum dot, or graphene oxide. Preferably, the percentage of carbon is adjusted such that the composite material is conductive immediately after deposition in a non-sintered form.

[0027] In one embodiment, the gallium is embedded in styrene-isoprene-styrene.

[0028] In one embodiment, the anode electrode includes gallium, carbon, styrene-isoprene-styrene block copolymer (Ga-C-SIS), and an anode current collector.

[0029] In one embodiment, the composite electrode is a non-sintered composite electrode. Preferably, the composite electrode is a non-sintered conductive electrode.

[0030] An anode electrode including the above electrode is also disclosed.

[0031] A cathode electrode including silver oxide, styrene-isoprene block copolymer (Ag 2 O-SIS), and a cathode current collector, and the above anode electrode and anode current collector, a stretchable battery, wherein each of the cathode current collector and the anode current collector includes a first current collector made of a composite material including liquid metal eutectic gallium-indium (EGaIn), silver (Ag), and styrene-isoprene block copolymer (SIS), and a second layer of a second current collector made of carbon black (CB) and styrene-isoprene block copolymer (SIS) is also disclosed.

[0032] Preferably, the anode includes gallium, carbon, and styrene-isoprene block copolymer (Ga-C-SIS).

[0033] In one embodiment, a damaged battery can be repaired by exposure to a solvent or solvent vapor that reconnects the damaged area by reconnecting the polymer binder. The materials in the battery can be recycled by dissolving soluble or reversible polymers in a solvent and collecting the embedded microparticles. Preferably, the battery is obtained by a non-sintering method.

[0034] In one embodiment, each of the electrodes is disposed on each of the current collectors.

[0035] In one embodiment, the second current collector is disposed on the first current collector to protect the first current collector from chemical corrosion by the electrolyte.

[0036] In one embodiment, the printable battery further comprises an electrolyte.

[0037] In one embodiment, the electrolyte comprises a gel or hydrogel selected from PAAM-alginate or its equivalents immersed in the electrolyte.

[0038] In one embodiment, the electrolyte is KOH.

[0039] In one embodiment, the anode electrode is arranged such that Ga-C-SIS gallium particles in the composite material are self-supplied to the surface of the electrode at the interface with the electrolyte and aggregate into larger particles.

[0040] In one embodiment, each of the cathode current collector and the anode current collector as well as the anode and the cathode includes an elastic binder.

[0041] In one embodiment, the elastic binder is selected from the list consisting of silicone, polyurethane, block copolymer or their elastomers.

[0042] In one embodiment, the ratio of eutectic gallium-indium (EGaIn): silver (Ag): styrene-isoprene block copolymer (SIS) of each of the first current collectors of the cathode current collector and the anode current collector is 0.65:1:0.65.

[0043] In one embodiment, each of the first current collectors of the cathode and the anode and the second current collector has a thickness of 10 to 400 μm, preferably 20 to 300 μm, preferably 50 to 200 μm, more preferably 90 μm to 130 μm.

[0044] In one embodiment, the thickness of each of the anode electrode and the cathode electrode is 50 to 1000 μm, preferably 100 to 500 μm.

[0045] In one embodiment, the battery further comprises a film as a seal, and preferably the film is selected from the list consisting of thermoplastic polyurethane, styrene block copolymer, silicone or their equivalents.

[0046] In one embodiment, the battery is printable, and in particular each of the anode, cathode and current collector is printable.

[0047] Also disclosed is an electronic circuit comprising a stretchable conductive trace made of a composite material including liquid metal eutectic gallium-indium (EGaIn), silver (Ag), and styrene-isoprene block copolymer (SIS) and a battery.

[0048] Also disclosed is a textile comprising a stretchable battery.

[0049] Also disclosed is a method for obtaining an electrode by adding a block copolymer solution in a solvent and carbon black, subsequently mixing, melting a certain amount of gallium, adding it to the mixture, and mixing. Preferably, a 10 to 20% (wt) styrene block copolymer solution in a solvent and carbon black are added, subsequently mixed at 500 to 5000 rpm for 1 to 5 minutes, melting a certain amount of gallium and adding it to the mixture, and mixing at 500 to 5000 rpm for 1 to 5 minutes to obtain an electrode.

[0050] In one embodiment, the method further comprises depositing an anode electrode on a second current collector of the anode current collector.

[0051] In one embodiment, the final ratio of carbon to gallium is 0.5% to 20%, preferably 1% to 5%.

[0052] In one embodiment, the deposition is carried out by digital printing, extrusion printing or 3D printing.

[0053] A method for obtaining a stretchable battery, mixing a 20 wt% styrene-isoprene solution in toluene with silver flakes at a weight ratio of 1:0.65 at 2000 rpm for 3 minutes, adding liquid metal eutectic gallium-indium, and mixing at 2000 rpm for 3 minutes to obtain a first current collector for each of the cathode current collector and the anode current collector; printing each of the first current collectors of the cathode current collector and the anode current collector on a substrate; adding carbon, preferably carbon black, at a weight ratio of 1:9 to a 20% styrene-isoprene solution and mixing at 2000 rpm for 3 minutes to obtain a second current collector for each of the cathode current collector and the anode current collector; printing each of the second current collectors of the cathode current collector and the anode current collector on top of the first current collector; adding carbon powder to a 20% styrene-isoprene solution, mixing at 2000 rpm for 3 minutes, adding Ag 2 O, and further mixing at 2000 rpm for 3 minutes to obtain a cathode electrode; depositing the cathode electrode on top of the second current collector of the cathode current collector; adding a 20 (wt)% SIS solution to carbon black, subsequently mixing at 2000 rpm for 3 minutes, adding a certain amount of toluene, mixing at 2000 rpm, melting a certain amount of Ga, and mixing at 2000 rpm for 3 minutes to obtain an anode electrode; depositing the anode electrode on top of the second current collector of the anode current collector A method including the above steps is also disclosed.

[0054] In one embodiment, the printing is digital printing selected from extrusion printing, direct ink writing and / or 3D printing.

[0055] In one embodiment, the method includes the step of encapsulating with a TPU film.

[0056] The following drawings provide preferred embodiments for explaining the present disclosure, but should not be construed as limiting the scope of the present invention.

Brief Description of the Drawings

[0057]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0058] The present disclosure relates to a fully digitally printed stretchable Ag-Ga battery using a combination of four digitally printable composite materials (Figure 1). All composite materials are of the non-sintered type, and since all processes are carried out at room temperature, they are compatible with a wide variety of heat-sensitive substrates.

[0059] In one embodiment, the first step includes printing a highly stretchable liquid metal (LM) composite material as the first (and main) current collector (CC). This stretchable two-phase composite material was recently introduced by the inventors

[18] and is composed of Ag flakes (silver flakes), eutectic gallium indium (EGaIn), and styrene-isoprene block copolymer (SIS). The ink is of the non-sintered type and benefits from high conductivity, a low gauge factor (0.9), stable behavior over thousands of cycles, and can be stretched up to 600% without losing conductivity. Unlike LM itself, the ink dries after deposition and does not bleed, allowing subsequent layers to be printed on top of the ink.

[0060] In one embodiment, the second CC layer is manufactured from carbon black (CB) and SIS. CB-SIS protects the first CC layer from chemical corrosion.

[0061] In one embodiment, the electrode consists of digitally printable Ag as the cathode 2 O-SIS and a novel printable gallium-carbon-SIS (Ga-C-SIS) as the anode.

[0062] A digitally printable gallium-carbon-SIS (Ga-C-SIS) material as the anode electrode is also disclosed (Figure 1A). (Ag 2 Used in O-Zn printed batteries) The movement from zinc to gallium was made because tests showed that it was very difficult to synthesize a digitally printable Zn (zinc) composite material. Several Zn composite materials were studied using various types of Zn particles and flakes. However, a stable digitally printable composite material that exposes sufficient zinc particles on the surface of the printed electrode could not be obtained. Furthermore, when attempts were made to increase the amount of Zn in the Zn-SIS composite material to more than about 40 wt%, the composite material was very viscous, brittle, and powdery and thus not printable. However, a digitally printable gallium-carbon-SIS containing 69.0 wt% gallium can be synthesized. Since gallium melts at 29 °C, the molten gallium can be mixed in situ with the polymer network structure (above 30 °C, but preferably at 50 - 60 °C). By such a top-down technique, the dimensions of the gallium particles in the polymer network structure can be adjusted by adjusting the mixing time and speed.

[0063] Furthermore, due to its low melting point, gallium metal can be mixed with the elastomer in a liquid state, whereby a high percentage of metal (e.g., 80% - 98%) can be mixed with the elastomer. At such weight percentages, mixing other metals such as zinc is difficult or impossible because the composite material becomes very sticky and difficult to mix when mixed. In addition, after curing, the composite material becomes very brittle and loses its elasticity. However, adding liquid gallium makes it easier to mix, and after deposition, the composite material is forgeable.

[0064] It should be noted that after melting, gallium remains liquid even below the cooling temperature. This is due to the supercooling effect of gallium. The extremely thin (3 nm) oxide layer that naturally forms around gallium particles protects the internal liquid gallium from solidifying. Thus, gallium composite materials are usually two-phase composite materials even at temperatures significantly lower than the melting point.

[0065] Unfortunately, even when gallium is mixed with an elastomer, a conductive composite material does not result. Since the elastomer cannot penetrate between gallium droplets, the composite material is not conductive even when the weight percentage of gallium is very high. This is due to the liquid and malleable nature of gallium, which, unlike solid metals, does not form a network structure within the infiltrating elastomer. Thus, the addition of carbon particles or carbon nanotubes is necessary for infiltration between gallium particles or droplets.

[0066] Other solid metals can be similarly used for infiltration between gallium particles, but for energy storage applications, carbon is preferred because it is inert even when in contact with acidic or basic electrolytes. Carbon does not react with the electrolyte. Furthermore, the carbon-elastomer network structure protects gallium particles from extreme exposure to the electrolyte and extends the life of the electrode.

[0067] In the present disclosure, the digital printed battery exhibits a maximum capacity of a record 19.39 mAh cm -2 which is the best value shown for a printed stretchable battery.

[0068] In one embodiment, the characterization of the battery's microstructure, electromechanical coupling, and electrochemical cycling is provided.

[0069] Surprisingly, even though it is not a liquid at room temperature, Ga-C-SIS exhibits liquid-like behavior as soon as it comes into contact with an electrolyte, resulting in self-supplying (i.e., transporting the underlying Ga particles to the surface) and self-aggregating (i.e., aggregation of adjacent gallium particles) characteristics. This property exposes more gallium to the electrolyte and delays the formation of a wasteful surface, thereby improving the overall areal capacity.

[0070] Generally, liquid metal batteries are attractive because they are flexible, self-healing, operate without dendrites [46, 52], and form a better conformal interface with the electrolyte, thereby enabling more efficient charge transfer. However, depositing / printing liquid electrodes is difficult. Therefore, Ga-C-SIS provides an excellent alternative. In one embodiment, Ga-C-SIS is a printable paste during extrusion, which changes into a non-bleeding composite material after deposition and generates only a liquid interface when in contact with the electrolyte.

[0071] The present disclosure also provides an example of a possible application, including a digitally printed stretchable multi-cell battery configured such that several battery cells are connected via printed stretchable traces to provide a desired output voltage and current.

[0072] In one embodiment, a wearable e-textile belt is provided having a digital printed sensor, interconnect, and battery for simultaneously acquiring and wirelessly communicating wireless communication, electrocardiogram (ECG), respiratory rate, heart rate, and body temperature.

[0073] In one embodiment, referring to FIG. 1A, Ga-C-SIS electrodes are synthesized by mixing carbon black (preferably in toluene) into an SIS solution in a planetary mixer, followed by adding molten gallium at 60° C. and further mixing. When melted, gallium acts in the same way as other liquid metal embedded elastomers (LMEEs) synthesized by EGaIn

[53] . Gallium particles are formed in situ during the mixing process, but the size of the gallium particles can be controlled by adjusting the mixing time and speed. However, similar to LMEEs, Ga-SIS is not conductive after deposition. The added carbon penetrates between the gallium microparticles, as also shown later in microscopic analysis, turning this into a conductive electrode (i, ii in FIG. 1D). Increasing the ratio of carbon to gallium improves the conductivity of the electrode. However, this reduces the active gallium content involved in the redox reaction, thereby reducing the areal capacity. Thus, in one embodiment, a CB:Ga ratio of 7.5 was maintained for the formulation of the electrode. As a result, the Ga-C-SIS composite material is printable, sinter-free, and conductive.

[0074] In one embodiment, Ag 2 O-SIS electrodes are prepared by first mixing carbon black with the SIS solution for 1 - 10 minutes, preferably 3 minutes, followed by adding Ag 2 O particles. The CB:Ag 2 O ratio is from 1:1 to 1:10. In one embodiment, the weight ratio of CB:Ag 2 O:SIS solution used was 0.4:1.6:2. FIG. 1B summarizes the chemical reactions in an Ag-Ga battery.

[0075] In one embodiment, regarding the current collector, referring to FIG. 1C, the battery is composed of two CC layers. The first CC, Ag-EGaIn-SIS, is prepared by mixing Ag flakes, EGaIn liquid metal, and an SIS block copolymer (BCP) solution in a planetary centrifugal mixer (see the method for reference). This is digitally printable and has high conductivity (7.02×105 S m -1 ) has high stretchability (over 600%). This is due to the very low gauge factor (0.9) of this CC layer, enabling effective charge transfer without sacrificing efficiency and excellent stretchability of the battery. As shown in the application section, the same material is also used for the direct digital printing of circuit interconnects, skin interface electrodes, and sensors, making it possible to fabricate the first layer of a complex integrated circuit and the battery CC simultaneously in one step. The second CC is a carbon-SIS composite material layer that protects the first CC layer against chemical corrosion by the electrolyte. This also ensures that the metal in the first CC does not participate in the redox reaction. All layers of the battery (current collector and electrodes) contain the same polystyrene-polyisoprene-polystyrene (SIS), enabling seamless integration of these layers and overall excellent stretchability. Here SIS is used, but other polymers such as styrene-ethylene-butylene-styrene thermoplastic elastomer (SEBS) can replace SIS. Furthermore, other block copolymers, polyurethanes, or silicones can be used as binders. However, styrene block copolymers such as SIS and SEBS provide excellent adhesion to the substrate, very elastic behavior, and reversible functionality. This means that the polymer can be reversibly changed to a gel or solid by exposure to a solvent. In one embodiment, the inventors repaired a cut battery by exposing it to toluene vapor. The inventors were also able to recover gallium from the electrode by dissolving the SIS-containing electrode in toluene.

[0076] To compare the areal capacity of the batteries according to the fabrication method, in two embodiments, the printing of the batteries was performed by screen printing and digital printing. In the case of screen printing, a CO 2 laser was used to pattern the screen mask, followed by the deposition of the CC layer and the electrodes.

[0077] In one embodiment, FIG. 1C shows all the steps for digital printing. Digital printing is performed using a desktop extrusion printer (Voltera V1). Compared to stencil printing, digital printing is much simpler and more self - sufficient as it eliminates the need for stencil preparation, manual deposition that often damages the traces, and stencil removal, as well as the need for low resolution. This also enables a higher printing resolution (lines and spaces of about 200 μm) compared to the resolution of about 1 mm in stencil printing. After printing each layer, a new cartridge is inserted for the subsequent material. The first printed layer, Ag - EGaIn - SIS, is also used as the CC of the battery and is also used to print interconnects, sensors, and antennas on the polymer film.

[0078] In one embodiment, in both printing mechanisms, layer - by - layer deposition was performed in the following order (i - vii in FIG. 1C). The first CC contains Ag - EGaIn - SIS, the second CC contains a carbon - SIS layer, the cathode contains an Ag 2 O - SIS composite material (cathode), and the anode contains Ga - C - SIS (anode). The (Ga - C - SIS) anode or Ag 2 O - SIS (cathode) are both deposited on the second CC, i.e., CB - SIS. The viscosities of all four materials are optimized for digital printing by changing the composite materials and adjusting the amounts of solvent and metal filler. Instead of Ag - SIS used in past Ag - Zn batteries, Ag 2 O - SIS is used, enabling the battery to supply energy immediately after fabrication without charging and exhibit an initial voltage of about 1.7V.

[0079] In one embodiment, FIG. 1E shows an example of a digital printed battery cell that can be bent, stretched, or twisted. Each of the layers of the printed material has a thickness of 10 - 400 μm, preferably 20 - 300 μm, preferably 50 - 200 μm, more preferably 90 μm - 130 μm. The total thickness of the three printed layers on each side is about 500 μm. The battery is printed on an ultrathin thermoplastic polyurethane (TPU) substrate having a thickness of 90 μm. This film partially melts when exposed to a temperature of about 150 °C, whereby the circuit and the battery can be transferred to a textile or other material using a heat transfer machine. At high temperatures, the melted adhesive fuses to the fibers of the textile, achieving seamless integration. This process is similar to that which has been used to transfer graphic designs to textiles in the clothing industry. The next step is to place a hydrogel electrolyte on top of the battery. Finally, the battery and the printed circuit are encapsulated and sealed by another TPU film that is heat transferred onto the device using the same technique.

[0080] In one embodiment, the production of the hydrogel electrolyte is carried out as follows. Although liquid electrolytes provide excellent charge transfer, solid / gel electrolytes are preferred because of their higher mechanical stability. In one embodiment, a polyacrylamide (PAAm)-alginate hydrogel, which is a tough, conductive, and stretchable hydrogel, is used as the electrolyte. The hydrogel is immersed in a 35% KOH solution (potassium hydroxide solution) for 24 hours to enable the ionic conductivity required for charge transfer within the battery.

[0081] In one embodiment, the battery is sealed by a film, preferably a thermoplastic polyurethane. In one embodiment, after all the electrodes are printed and the hydrogel is placed, the battery should be sealed to avoid any leakage of the electrolyte. To seal the battery, a heat - transferable TPU (thermoplastic polyurethane) film is used, and the edges are sealed to a substrate (e.g., SIS or another TPU film) using a hot iron. The heat - transferable TPU film is composed of TPU and an adhesive that melts at a temperature lower than the temperature of the film itself (150 °C). Thus, when heat is selectively applied using iron, the edges of the electrodes and the hydrogel bond to each other, thereby protecting the battery and the hydrogel.

[0082] After fabrication, the battery was electrochemically characterized. The characterization was performed using a homemade potentiostat / galvanostat (PGSTAT) based on open - source hardware

[54] , which allowed up to 10 batteries to be characterized simultaneously.

[0083] In one embodiment, FIG. 2A shows the discharge profile of the battery, which exhibits a stable plateau at approximately 1.7 V. The flatness of the discharge voltage indicates the stability of the battery during discharge. Referring to FIG. 2B, voltage peaks for different charging and discharging currents were obtained to compare the voltage values of both printing methods. Surprisingly, when the current is increased, the digital - printed battery shows more stable behavior compared to the stencil - printed battery.

[0084] In one embodiment, the battery was characterized under mechanical strain. First, the performance of the device was analyzed while simultaneously stretching and discharging. Figure 2C shows that the voltage of the battery remains above 0.8V until reaching an extreme value of about 130% strain (133% on average for three batteries). The achievement of this high value is due to the high stretchability of all layers of the battery, including the current collector, electrodes, and hydrogel. Up to 60% strain, no significant change in the internal resistance of the battery was observed, as demonstrated by the stability of the discharge voltage up to this point.

[0085] In another experiment, five batteries were first stretched until reaching 100% strain and then characterized. As shown in Figure 2D, the areal capacity of the battery increased slightly compared to the initial state battery, with an average value of about 8.15 mAh cm -2 This phenomenon was also observed in Leal, C., Lopes, P. A. P. A., Serra, A. A., Coelho, J. F. J. J. F. J. J., De Almeida, A. T. A. T. A. T., and Tavakoli, M. (2020) [3], and seems to be related to the fact that better contact between the hydrogel and the electrodes is ensured during strain, resulting in an increase in the amount of active material exposed to the electrolyte.

[0086] A comparison between digital printed electrodes and stencil printed electrodes was also carried out.

[0087] The first experiment using Ga-C-SIS electrodes was conducted using screen-printed batteries for the purpose of replication and comparing the results with a conventional Ag-Zn battery. Subsequently, a digital printed version of the battery was fabricated, resulting in surprising results. Referring to Figure 2D, digital fabrication increased the areal capacity of the battery to (19.39 mAh cm -2) It can be seen that it is significantly increased. This is consistent with the improvement in the behavior of the digital printed battery observed in Figure 2B. The reason for this difference is clearly observed in Figure 2G. The digital printed electrode exposes a considerably larger amount of gallium on the surface compared to the stencil printed electrode. This seems to be related to the deposition procedure. During stencil printing, a spatula should be used to apply mechanical pressure to the material. Considering that the density of gallium is higher than that of carbon, the pressure applied to the uncured ink contributes to the sedimentation of gallium in the lower layer. When deposition is performed by extrusion printing, the material remains in a uniformly distributed state.

[0088] Further SEM analysis of the upper surfaces of the stencil printed battery and the digital printed battery also confirmed an improvement in the distribution of gallium microparticles in the digital printed electrode. Cross-sectional analysis showed that the gallium particles of the stencil printed electrode are considerably larger and accumulate at the bottom of the electrode.

[0089] Surprisingly, the Ga-C-SIS electrode presents an excellent combination of printability, conductivity, and chemical stability in a KOH electrolyte. The role of the SIS binder is to impart adhesiveness and stretchability to the composite material. In addition, the viscosity of the SIS solution can be adjusted to a desirable value for extrusion printing by changing the amount of solvent.

[0090] The combination of Ga and SIS enables the fabrication of printable and adhesive electrodes, but this composition does not result in a conductive composite material. Carbon black generates a penetration network structure between these particles, thereby enabling conductivity.

[0091] In one embodiment, Figure 2E compares the areal capacity with respect to the maximum stretchability of the stencil printed battery and the digital printed battery in contrast to past research data for stretchable flat batteries. As a reference point, the inventors used a non-stretchable Ag that showed a considerable areal capacity of 12.5 mAh cm -2 with a considerable areal capacity 2An O-Zn battery is also added. As can be seen, the highest values were obtained for the maximum strain tolerance and areal capacity. In addition, the results also refer to a fully digitally printed stretchable battery. The Ag-Ga battery has a weight capacity of 104.42 mA h g-1 considering the mass of the entire electrode, and a weight capacity of 162.5 mA h g-1 considering only the mass of the metal in the composite material (subtracting carbon and SIS). In the latter case, this is about 14% of the theoretical value of the anode.

[0092] Referring to Figure 2F, the self-discharge rate of the battery was studied by achieving a discharge profile at a load of 0. The battery showed a durability of at least 13 days after fabrication, which is about three times better than the state of prior art Ag-Zn batteries having a durability of less than 5 days. After 13 days, the battery still showed an operating voltage higher than 1 V. Figure 2H shows 100 electrochemical cycles performed by the battery at a constant charge-discharge current of 0.4 mA / cm 2 This result is comparable to other LM-based thin film batteries

[50] .

[0093] Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis were performed to investigate the material and morphology of the electrodes over multiple electrochemical cycles. Figure 3 shows the above evolution regarding the anode electrode.

[0094] Generally, one of the reasons that printed batteries provide lower capacities than conventional bulk batteries is that composite materials rather than bulk metals need to be used within the printed batteries. Accordingly, only a certain percentage of the metal is exposed at the surface and some of the metal particles are embedded in the underlying layer. The Ga-C-SIS electrode appears to address this issue to some extent by self-supplying more gallium to the surface. Comparing a fresh electrode (i in FIG. 3A) with an electrode exposed to the electrolyte (i in FIG. 3B), it can be seen that more gallium is exposed at the surface. Note that FIG. 3B is at a magnification 10 times lower compared to FIG. 3A. After contact with the electrolyte, the gallium particles aggregate and cover a significant amount of the electrode surface (i in FIG. 3B). This results in a self-aggregation and self-supplying property that occurs only when the electrode contacts the electrolyte. This self-supplying mechanism improves battery performance by exposing more gallium at the surface and delaying the formation of a non-functional surface or dendrites in the absence of metal as recently shown in liquid alloy Na-K batteries

[52] . The solubility of gallium oxide thin films in KOH solution, the low melting point of gallium (29 °C), and the heat generated during the gallium-KOH reaction contribute to the formation of a certain amount of liquid gallium droplets that can move within the electrode and aggregate by adjacent electrodes. The Ga-C-SIS electrodes were analyzed before and after exposure to KOH. It was shown that some gallium droplets were formed and reached the electrode surface. The inventors note that in the assembled battery, instead of a liquid KOH solution, a solid hydrogel pressed against the electrodes by an encapsulation film is used, and thus these gallium droplets are confined to the surface. Thus, the gallium spheres cannot move freely in the electrolyte and therefore effectively contribute to the redox reaction.

[0095] In one embodiment, self-aggregation of gallium and the exposure of a large amount of gallium after contact between the electrode and KOH are also confirmed by the elemental intensity map (comparison between ii and iii in Fig. 3A and ii, iii, and iv in Fig. 3B). Comparing the gallium intensity map of the electrode in the new state with the gallium intensity map of the electrode after contact with KOH, it can be seen that there is a considerably larger amount of gallium on the surface of the electrode in the latter case.

[0096] In one embodiment, Fig. 3C shows the fine porosity increase of the electrode after discharge, and Fig. 3D shows the anode microstructure after 100 cycles. The needle-like structure grows during the electrochemical cycle ((GaO33-)).

[0097] In one embodiment, Fig. 4 shows a proposed model for the change of the Ga-C-SIS anode after contact with the electrolyte. Immediately after contact with KOH, the gallium oxide shell is dissolved, and some of the gallium particles come out to the surface of the electrode. When the top layer is limited by the hydrogel and the encapsulating layer, some of these particles aggregate. At the same time, voids remain in the microstructure due to the detachment of some of these Ga particles, and the underlying gallium particles are exposed to the electrolyte, whereby further particles aggregate and are supplied to the upper surface.

[0098] To demonstrate the scalable and autonomous fabrication of printed Ag-Ga batteries and their respective applications, one embodiment was designed where 12 printed battery cells were connected in series and parallel in a 3×2 format to form two batteries (Figs. 5A and 5B). All four composite materials were digitally printed using an extrusion printer. The Ag-EGaIn-SIS ink, which is the first CC layer, was used for printing the interconnections between the battery and the SMD LED, and the connections between the battery cells. Thus, the printed lines can be used to connect the battery cells in series and parallel to adjust the output current and voltage for the required applications. Expanding on this, it is also possible to print electrodes, sensors, and antennas simultaneously with the battery. In one embodiment, Figs. 5C, 5D, and 5E show the printed battery before and after integration into a monitoring wearable e-textile. The monitoring belt incorporates printed electrodes for electrocardiogram (ECG) monitoring, printed strain gauges for respiration monitoring, and a digital temperature sensor under the armpit. The available space on the belt side for printing the battery was utilized. This solution provided sufficient energy to power the belt for 22 hours to continuously acquire data and transmit clinical-grade ECG data at 100 Hz via Bluetooth. Since the desired input power for the biomonitoring board is above 2 V, two battery cells were in series. However, as discussed in other research materials

[55] , placing two batteries in series results in a significant decrease in efficiency. As an alternative to this large series battery (2×10 cm 2 ), a significantly smaller 3 cm 2 battery is provided that can achieve 9 hours and 20 minutes of autonomous operation for ECG monitoring.

[0099] In one embodiment, a high areal capacity (19.4 mAh cm -2) and a maximum strain tolerance of 130%. A fully digital printed stretchable battery is provided. The Ag-Ga battery consists of four digitally printable and stretchable composite materials: Ag-EGaIn-SIS which is the first CC, CB-SIS which is the second CC, Ag 2 O-SIS cathode electrode and a novel Ga-C-SIS anode electrode. The Ga-C-SIS electrode showed a combination of improved properties in comparison with zinc-SIS electrodes, including higher areal capacity, higher maximum strain tolerance, and being digitally printable. The digital printed battery by extrusion deposition showed a considerably higher areal capacity and higher stability towards electrochemical cycles compared to the stencil printed version of the battery with composite materials of the same materials. It can be seen that digital printing exposes a larger amount of gallium on the surface of the electrode compared to stencil printing, which results in significantly improved areal capacity and electrochemical cycles.

[0100] In one embodiment, the microstructure of the Ga-C-SIS electrode was analyzed by optical microscopy, electron microscopy, and EDS elemental mapping. The results showed that when the electrode was exposed to a hydrogel electrode containing KOH, liquid gallium droplets were formed, which self-supplied small gallium particles from the underlying surface, self-aggregated into larger aggregates, thereby improving the performance of the battery. This is due to the fact that the underlying gallium particles can reach the surface of the electrode, which is not possible when using other composite materials such as Zn-SIS. The battery showed an open circuit discharge three times higher than that of a similar battery with a zinc anode electrode. Furthermore, the Ga-C-SIS electrode contains 69 wt% gallium and remains a uniform and digitally printable composite material. In comparison, some attempts to digitally print the Zn-SIS electrode failed due to the formation of a very brittle and non-uniform composite material when the zinc content by percentage exceeded 40 wt%. This should also be one of the factors contributing to the excellent areal capacity of the Ag-Ga battery.

[0101] In one embodiment, the same electrolyte was used for both electrodes without using any separator.

[0102] In one embodiment, additives or electrolytes on the electrodes that generally further improve the performance of the battery can be used.

[0103] Several applications can arise for printed stretchable integrated electronic systems where the electrodes, sensors, and interconnects are printed together with the first CC layer of the battery. Thereby, the required voltage and current of the battery can be specifically adjusted to desired values. One application is obtained for a bio-monitoring e-textile having a printed AG-Ga battery that operates autonomously for 22 hours energetically and acquires and transmits clinical-grade ECG data at 100 Hz via Bluetooth.

[0104] All materials were used as received unless otherwise specified. Gallium and indium were procured from Rotometals and Nova Elements. EGaIn was manufactured by melting and mixing 75.5 wt% Ga and 24.5 wt% In at 250 °C for 24 hours. Silver flake 071 was procured from Technic, Inc. The silver flake has a particle size of more than 5 μm. Carbon black was procured from Alfa Aesar (45527). Polystyrene block - polyisoprene block - polystyrene (SIS) 14% styrene was procured from Alfa Aesar. Silver(I) oxide 99+% (metal basis) was procured from Alfa Aesar (11407). Sodium alginate, methylenebisacrylamide (BIS), acrylamide, Irgacure, and calcium sulfate were procured from Sigma - Aldrich.

[0105] Thinky ARE - 250 was used as the mixer. In the case of stencil printing, all plastic stencils are CO 2It was cut using a laser cutter (VLS3.50). All digital printed batteries were fabricated using a Voltera printer.

[0106] In one embodiment, the preparation of Ag-In-Ga-SIS (the first CC) included the following steps. A 20 wt% SIS solution in toluene was prepared using a Thinky mixer. The solution was then mixed with Ag flakes at 2000 rpm for 3 minutes at a weight ratio of 1:0.65. Then, after adding EGaIn, it was mixed at 2000 rpm for 3 minutes. The mixing ratio per weight was Ag:EGaIn:SIS solution: 1:0.65:0.65.

[0107] In one embodiment, the preparation of CB-SIS (the second CC) included the following steps. CB was added to a 20% SIS solution at a weight ratio of 1:9 and mixed at 2000 rpm for 3 minutes.

[0108] In one embodiment, Ag 2 The preparation of the O-SIS cathode electrode included the following steps. CB powder was added to a 20% SIS solution and mixed at 2000 rpm for 3 minutes. Ag 2 O was added and further mixed at 2000 rpm for 3 minutes. The weight ratio of CB:Ag 2 O:SIS solution: 0.4:1.6:2.

[0109] In one embodiment, the preparation of the Ga-C-SIS anode electrode included the following steps. The Ga-C-SIS electrode was prepared by adding 2 g of a 20 (wt)% SIS solution to 0.6 g of CB and subsequently mixing at 2000 rpm for 3 minutes. Then, after adding 1 g of toluene to the aforementioned mixture, it was mixed at 2000 rpm for 20 minutes. Finally, 8 g of Ga was melted and added and mixed at 2000 rpm for 3 minutes. At the time of addition, the temperature of gallium was 60 °C.

[0110] In one embodiment, the assembly of the stencil printed electrode included the following steps. CO 2Using a laser (Universal), a stencil was patterned into a desired shape on a plastic film. A heat press was used to transfer a TPU film onto a textile. A stencil was used to deposit Ag-In-Ga-SIS ink and left to dry for 1 hour. Next, a layer of CB-SIS was deposited. Next, a stencil was used to deposit an active electrode, and a 1 cm 2 square was cut out from this active electrode.

[0111] In one embodiment, the assembly of the digital printed electrodes involved the following steps. The digital printed battery was fabricated using the same sequence but with a digital printer (Voltera V1). After printing each layer, the material cartridge was changed to the next material. When soft substrates were used, these substrates had to be attached to the substrate using an adhesive film (e.g., a double-sided adhesive film). The printing was performed using a nozzle with an orifice of 200 μm or 250 μm.

[0112] In one embodiment, the morphological and microstructural behavior of the composite material was characterized by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and mapping (Bruker Nano GmbH, Berlin, Germany, Esprit 1.9 and detector type: XFlash410).

[0113] In one embodiment, the hydrogel electrolyte was the same as that disclosed in [3]. 0.732 g of sodium alginate, 0.006 g of BIS, and 4.5 g of acrylamide were dissolved in 30 mL of water. Then, the solution was degassed and 20 mL was transferred to a syringe. 0.0492 g of Irgacure and 0.0646 g of calcium sulfate were placed in a different syringe containing 1 mL of water. Using a syringe adapter, the contents of both syringes were mixed. This was cast onto glass and cured under UV light for approximately 3 hours. Immediately after curing, the hydrogel was placed in a 35 (wt)% KOH solution for 24 hours.

[0114] In one embodiment, the integration of the printed battery onto the belt was assisted by a transfer method using transfer tattoo paper (TTP). First, the TTP was attached onto the TPU and peeled off immediately after being lightly pressed, leaving an adhesive layer on the surface. Next, the printed battery was placed on this layer and connected to the belt. Finally, the hydrogel was placed on the electrodes and the battery was sealed using a layer of tegaderm film (3M). The terminals of the battery were connected to the interconnects printed using the same Ag-EGaIn-SIS ink. In this example, the circuits and batteries to be printed had to be printed separately in two runs because the circuit with the battery was larger than the working area of the printer.

[0115] The mean and standard deviation of Figure 2G were based on three samples and calculated using Excel software.

[0116] In any case, the term "comprising" as used herein is intended to indicate the presence of the recited features, integers, steps, components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0117] The present disclosure should in no way be construed as being limited to the described embodiments, and those skilled in the art can foresee numerous possible modifications of the described embodiments. The above embodiments can also be combined.

[0118] The following claims further define specific embodiments of the present disclosure.

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Claims

1. A composite electrode comprising a polymer containing carbon particles impregnated with gallium or a gallium-indium alloy.

2. A composite electrode according to claim 1, wherein the carbon:gallium ratio in the polymer is 0.5% to 20%, preferably 1% to 5%, for penetration between gallium atoms.

3. A composite electrode according to claim 1, wherein the gallium is in the form of microdroplets in the range of 0.1 μm to 1000 μm.

4. A composite electrode according to claim 1, wherein the polymer is selected from the group consisting of silicone, polyurethane, styrene block copolymer, or mixtures thereof.

5. A composite electrode according to claim 1, wherein the amount of the polymer is 2 to 20% by weight, preferably 4 to 9% by weight, relative to the composite material.

6. A composite electrode according to claim 1, wherein the carbon is in the form of nanoparticles or microparticles, and is selected from carbon black, carbon nanowires, graphene quantum dots, or graphene oxide.

7. A composite electrode according to claim 1, wherein the polymer is a styrene-isoprene-styrene block copolymer.

8. A composite electrode according to claim 7, wherein the gallium is embedded in the styrene-isoprene-styrene.

9. A composite electrode comprising gallium, carbon, and styrene-isoprene-styrene block copolymer (Ga-C-SIS), and an anode current collector.

10. A composite electrode according to claim 1, wherein the composite electrode is a non-sintering type electrode.

11. An anode electrode comprising the electrode according to any one of claims 1 to 10.

12. Silver oxide and styrene-isoprene block copolymer (Ag ２ O-SIS) and a cathode electrode including a cathode current collector, The anode electrode and anode current collector according to claim 11 A retractable battery equipped with, Each of the cathode current collector and the anode current collector is, A first current collector made of a composite material containing liquid metal eutectic gallium-indium (EGaIn), silver (Ag), and styrene-isoprene block copolymer (SIS), A second current collector second layer consisting of carbon black (CB) and styrene-isoprene block copolymer (SIS) Equipped with, Extendable battery.

13. A retractable battery according to claim 12, wherein each of the electrodes is positioned on each of the current collectors.

14. A retractable battery according to claim 12, wherein the second current collector is positioned on the first current collector to protect the first current collector from chemical corrosion by an electrolyte.

15. A retractable battery according to claim 12, wherein the printable battery further comprises an electrolyte.

16. A stretchable battery according to claim 14, wherein the electrolyte comprises a gel or hydrogel selected from PAAM-alginate or equivalents immersed in the electrolyte.

17. A retractable battery according to claim 14, wherein the electrolyte is KOH.

18. A retractable battery according to claim 12, wherein the anode electrode is positioned such that the Ga-C-SIS gallium particles in the composite material are self-supplied to the surface of the electrode at the interface with the electrolyte and aggregate to form larger particles.

19. A retractable battery according to claim 12, wherein each of the cathode current collector and the anode current collector, and the anode and the cathode, include an elastic binder.

20. A retractable battery according to claim 12, wherein the elastic binder is selected from the list of silicone, polyurethane, block copolymer or equivalent elastomers.

21. A retractable battery according to claim 12, wherein the ratio of eutectic gallium-indium (EGaIn):silver (Ag):styrene-isoprene block copolymer (SIS) in the first current collectors of the cathode current collector and the anode current collector is 0.65:1:0.

65.

22. A retractable battery according to claim 12, wherein the first current collector and the second current collector of the cathode and anode, respectively, have a thickness of 10 to 400 μm, preferably 20 to 300 μm, preferably 50 to 200 μm, and more preferably 90 μm to 130 μm.

23. A retractable battery according to claim 12, wherein the thickness of the anode electrode and the cathode electrode are 50 to 1000 μm, preferably 100 to 500 μm.

24. A stretchable battery according to claim 12, further comprising a film as a seal, preferably the film being selected from the list of thermoplastic polyurethane, styrene block copolymer, silicone or equivalents thereof.

25. A retractable battery according to claim 12, wherein the battery is printable, and in particular the anode, the cathode and the current collector are each printable.

26. An electronic circuit comprising a stretchable conductive trace made of a composite material containing liquid metal eutectic gallium-indium (EGaIn), silver (Ag), and styrene-isoprene block copolymer (SIS), and the battery described in claim 12.

27. A textile comprising the retractable battery described in claim 12.

28. A method for obtaining an electrode according to any one of claims 1 to 10, comprising adding a block copolymer solution and carbon black in a solvent, then mixing, dissolving a certain amount of gallium and adding it to the mixture, and then mixing.

29. A method according to claim 28, further comprising the step of depositing the anode electrode on the second current collector of the anode current collector.

30. A method according to claim 28, wherein the final ratio of carbon to gallium is 0.5% to 20%, preferably 1% to 5%.

31. A method according to claim 29, wherein the deposition is carried out by digital printing, extrusion printing or 3D printing.

32. A method for obtaining the expandable battery described in claim 12, The first current collectors for the cathode current collector and the anode current collector are obtained by mixing a 20 wt% styrene-isoprene solution in toluene with silver flakes at a weight ratio of 1:0.65 for 3 minutes at 2000 rpm, adding liquid metal eutectic gallium-indium, and mixing at 2000 rpm for 3 minutes. The steps include printing the first current collectors of the cathode current collector and the anode current collector onto the substrate, The steps include adding the carbon, preferably carbon black, in a weight ratio of 1:9 to a 20% styrene-isoprene solution and mixing at 2000 rpm for 3 minutes to obtain the second current collectors for the cathode current collector and the anode current collector, respectively, The steps include printing the second current collectors of the cathode current collector and the anode current collector onto the first current collector, Add carbon powder to a 20% styrene-isoprene solution and mix at 2000 rpm for 3 minutes, then Ag ２ The steps include adding O and further mixing at 2000 rpm for 3 minutes to obtain the cathode electrode, The steps include depositing the cathode electrode on the second current collector of the cathode current collector, The anode electrode is obtained by adding a 20 (wt) SIS solution to carbon black, then mixing at 2000 rpm for 3 minutes, adding a certain amount of toluene, mixing at 2000 rpm, dissolving a certain amount of Ga, and mixing at 2000 rpm for 3 minutes. The steps include depositing the anode electrode on the second current collector of the anode current collector, Methods that include...

33. A method according to claim 31, wherein the printing step is digital printing selected from extrusion printing, direct ink writing and / or 3D printing.

34. A method according to claim 32, comprising the step of encapsulating with a TPU film.

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