Biodegradable Electrochemical Devices

Abstract

A biodegradable solid aqueous electrolyte composition, an electrochemical device incorporating the electrolyte composition, and a method therefor are provided. The electrolyte composition can include a copolymer hydrogel and a salt dispersed in the hydrogel. The copolymer can include at least two polycaprolactone chains attached to a polymer center block. The electrochemical device can include an anode, a cathode, and an electrolyte composition disposed between the anode and the cathode. The electrolyte composition can include a crosslinked biodegradable polymer material that is radiation-curable prior to being crosslinked.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION The presently disclosed embodiments or implementations are directed to biodegradable electrochemical devices, their solid aqueous electrolytes, and methods for fabricating or synthesizing the same. [Background technology]

[0002] The number of batteries produced worldwide is continuously increasing as a result of the increasing need for portable and remote power sources. In particular, several emerging technologies require batteries to power implantable electronic devices. For example, implantable electronic devices, such as portable and wearable electronic devices, Internet of Things (IoT) devices, patient health monitoring, structural monitoring, environmental monitoring, smart packaging, and the like, rely on batteries for power supply. Although conventional batteries can be partially recycled, no batteries currently available on the market are environmentally friendly or biodegradable. Thus, the increased production and use of conventional batteries will result in a corresponding increase in toxic and harmful waste in the environment if the batteries are not properly disposed of or recycled. In view of the foregoing, there is a need to develop biodegradable batteries, especially for applications that utilize disposable batteries for a limited time before being discarded.

[0003] Furthermore, to meet the demand for flexible, low-cost, medium- or low-performance batteries, all-printed batteries have been developed that are commercially available as single-use disposable batteries, but none of these all-printed batteries are biodegradable.

[0004] It is generally accepted that one of the greatest challenges in the production of biodegradable batteries is the development of biodegradable polymer electrolytes, which are the primary polymer-based components of all-printed batteries. Additionally, a further challenge is the development of such biodegradable polymer electrolytes that can also be printed using existing printing technologies.

[0005] Conventional biodegradable polymer electrolytes often include a combination of a biodegradable polymer and a conductive salt. To obtain the biodegradable polymer electrolyte, the biodegradable polymer and conductive salt are dissolved in a solvent, which is then subsequently evaporated at a relatively slow rate to produce a solid polymer electrolyte film. These conventional biodegradable polymer electrolytes often have low ionic conductivity at ambient temperatures (e.g., about 10 at RT) due to the low mobility of ions in the biodegradable polymer. -5 However, sufficient conductivity can be achieved if the polymer electrolyte is heated to a temperature sufficient to allow polymer chain mobility (i.e., the operating temperature), thereby allowing ions to move more freely through the polymer electrolyte structure. Sufficient conductivity can also be achieved by incorporating additives that suppress the crystallinity of the polymer electrolyte, but this reduces its operating temperature. Thus, biodegradable polymer electrolytes that can operate with sufficient conductivity at room temperature are limited.

[0006] In addition to the aforementioned drawbacks, conventional biodegradable polymer electrolytes also suffer from the problem of lengthy manufacturing processes due to the time required to evaporate the solvent during production. For example, vacuum and / or temperature-assisted evaporation often requires several hours to evaporate the solvent for preparing conventional biodegradable polymer electrolytes. This limits the compatibility of conventional biodegradable polymer electrolytes with high-throughput printing processes, in which successive layers must be printed on top of each other within minutes.

[0007] Thus, what is needed is a printable, biodegradable electrochemical device, its solid aqueous electrolyte, and methods for synthesizing and fabricating the same. Summary of the Invention

[0008] The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor is it intended to delineate the scope of the disclosure. Rather, its primary purpose is merely to present one or more concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0009] The present disclosure can provide an electrochemical device including an anode, a cathode, and an electrolyte composition. The electrolyte composition can be disposed between the anode and the cathode. The electrolyte composition can include a cross-linked, biodegradable polymeric material that can be radiation-curable before being cross-linked.

[0010] In some examples, multiple electrochemical devices are provided. The multiple electrochemical devices can be printed simultaneously on a web as an array in a parallel process. In one example, the multiple electrochemical devices can be printed independently or as linked elements.

[0011] In some examples, a plurality of electrochemical devices are provided. The biodegradable polymeric material of the plurality of electrochemical devices can be radiation curable in about 10 milliseconds (ms) to about 100 ms.

[0012] In some examples, the biodegradable polymeric material prior to crosslinking can include radiation-curable functional groups, which can include one or more of acrylate, vinyl ether, allyl ether, alkene, alkyne, thiol, or combinations thereof.

[0013] In some examples, the electrolyte composition can be derived from a radiation-curable electrolyte precursor composition, which may include at least one photoinitiator.

[0014] In some examples, the at least one photoinitiator may include one or more of lithium acylphosphinate (LAP), IRGACURE 2959, sodium 4-[2-(4-morpholino)benzoyl-2-dimethylamino]-butylbenzenesulfonate (MBS), monoacylphosphine oxide (MAPO) salts Na-TPO and Li-TPO, bisacylphosphine oxide salts Na-BAPO, Li-BAPO, thioxanthone derivatives, benzophenone derivatives, Irgacure 754, PEG-modified BAPO, or a combination thereof.

[0015] In some cases, the crosslinked biodegradable polymeric material can have a Young's modulus of about 0.10 MPa to about 100 MPa. In some cases, the crosslinked biodegradable polymeric material can have a yield strength of about 5 kPa or greater.

[0016] In some examples, the electrochemical device can include one or more biodegradable substrates. The one or more biodegradable substrates can be stable up to about 120°C. The one or more biodegradable substrates can maintain structural integrity with less than 10% dimensional change after exposure to about 120°C. The one or more biodegradable substrates can include one or more of polylactic acid (PLA), polylactic-co-glycolic acid (PLGA), silk fibroin, chitosan, polycaprolactone (PCL), polyhydroxybutyrate (PHB), rice paper, cellulose, or a combination or composite thereof.

[0017] In some cases, the electrolyte composition can include a hydrogel, which can include water and a cross-linked biodegradable polymeric material.

[0018] In some examples, the electrolyte composition can include a co-solvent, which can include one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, or a combination thereof.

[0019] In some examples, the anode may include one or more of Zn, Li, C, Mg, an Mg alloy, a Zn alloy, or a combination thereof.

[0020] In some examples, the cathode may include one or more of Fe, MnO2, C, Au, Mo, W, MoO3, Ag2O, Cu, or a combination thereof.

[0021] In some examples, the radiation-curable electrolyte precursor composition can include one or more of ZnCl, NH, Cl, NaCl, PBS, NaSO, ZnSO, MnSO, ​​MgCl, CaCl, FeCl, LiPF, KOH, NaOH, or a combination thereof. In some examples, the concentration of the radiation-curable electrolyte precursor composition can be from about 3 M to about 10 M.

[0022] The present disclosure also provides an electrochemical device including an anode, a cathode, and an electrolyte composition disposed between the anode and the cathode. The anode can include a first biodegradable binder. The cathode can include a second biodegradable binder. The electrolyte composition can include a cross-linked biodegradable polymer material that is radiation-curable before being cross-linked.

[0023] In some cases, the cathode and / or anode are arranged in a stacked configuration.

[0024] In some examples, the cathodes and / or anodes are arranged in a lateral XY planar geometry.

[0025] In some examples, each of the cathode and / or anode can include a biodegradable binder, which can include one or more of chitosan, polylactic-co-glycolic acid (PLGA), cellulose acetate butyrate (CAB), polyhydroxybutyrate (PHB), or a combination thereof.

[0026] In some examples, each of the cathode and / or anode can include both an active layer and a current collector layer.

[0027] In some examples, the cathode, anode, and electrolyte compositions are printed.

[0028] In some cases, the electrochemical device may be flexible.

[0029] In some cases, the crosslinked biodegradable polymeric material may be radiation curable for about 10 milliseconds (ms) to about 100 ms before being crosslinked.

[0030] The present disclosure may further provide a process or method for fabricating an electrochemical device. The process may include the step of preparing a biodegradable substrate. The process may also include the step of depositing an electrode composition and, optionally, the step of thermally drying the electrode composition. The process may further include the step of depositing a biodegradable radiation-curable electrolyte composition. The process may also include the step of radiation-curing the biodegradable radiation-curable electrolyte composition after thermally drying the optional electrode composition. The biodegradable substrate may be thermally compatible with the optional thermal drying.

[0031] In some examples, the steps of depositing the electrode composition and depositing the biodegradable radiation curable electrolyte composition can include printing.

[0032] In some examples, the step of radiation curing the biodegradable radiation-curable electrolyte composition can be completed in about 10 milliseconds (ms) to about 100 ms.

[0033] In some examples, the step of radiation curing the biodegradable, radiation-curable electrolyte composition results in a crosslinked biodegradable electrolyte composition having a Young's modulus of about 0.10 MPa to about 100 MPa and a yield strength of about 5 kPa or greater.

[0034] In some examples, the process may further include depositing a biodegradable adhesive layer.

[0035] In some cases, the biodegradable substrate may be weldable / bondable without the use of additional adhesives.

[0036] In some examples, the process can include depositing a biodegradable adhesive layer on the tab.

[0037] In some cases, the biodegradable substrate can be provided as a web-fed continuous roll.

[0038] In some cases, the electrode composition may be a metal foil composition.

[0039] In some examples, the process can include depositing a second electrode composition, which can be a different metal foil composition.

[0040] In some cases, the biodegradable substrate may be a continuous web or may be supported by a continuous web.

[0041] In some cases, multiple electrochemical devices can be printed simultaneously as separate or linked elements on a web as an array in a parallel process.

[0042] The present disclosure also provides a biodegradable solid aqueous electrolyte comprising a copolymer hydrogel and a salt dispersed in the hydrogel. The copolymer can include at least two polycaprolactone chains attached to a polymeric central block.

[0043] In some instances, the center block of the polymer can be derived from a naturally occurring biodegradable polymer having at least two free hydroxyl groups.

[0044] In some examples, the polymer center block can include a hydroxyl-bearing polysaccharide, a biodegradable polyester, or a hydroxy fatty acid.

[0045] In some examples, the polymeric center block can include polyvinyl alcohol or polybutylene succinate or castor oil.

[0046] In some cases, the hydrogel may include a copolymer loading of 20% by weight or more, preferably 30% by weight or more, and even more preferably 50% by weight or more, based on the total weight of the hydrogel.

[0047] In some cases, the hydrogel may include a copolymer loading of about 5% to about 50% by weight, based on the total weight of the hydrogel.

[0048] In some examples, the salt can include ammonium chloride (NH4Cl), zinc chloride (ZnCl2), or a mixture thereof.

[0049] In some cases, the salt may be present in the electrolyte at a concentration of at least 0.5M.

[0050] In some cases, the salt may be present in the electrolyte at a concentration of at least 3M and at most 10M.

[0051] In some examples, the electrolyte can further include a nanomaterial additive. In at least one example, the nanomaterial additive can include cellulose nanocrystals, chitin nanocrystals, chitosan nanocrystals, starch nanocrystals, silicon oxide, aluminum oxide, layered silicates, lime, or a mixture of any of these.

[0052] In some examples, the electrolyte may further include water and a co-solvent. The co-solvent may include one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, or a combination thereof. In a preferred example, the co-solvent may be selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and a combination thereof.

[0053] In some examples, the hydrogel can have or include a viscosity of about 1,000 cP to about 1.0E+6 cP.

[0054] The present disclosure may also provide an electrochemical device including an anode, a cathode, and the biodegradable solid aqueous electrolyte of any one of paragraphs

[0042] to

[0053] . The biodegradable solid aqueous electrolyte may be disposed between the anode and the cathode.

[0055] In some examples, the biodegradable solid aqueous electrolyte can be printed onto the cathode or anode.

[0056] The present disclosure may further provide a process for producing a solid aqueous electrolyte. The process may include dissolving a salt and a functionalized copolymer in an aqueous solution. The copolymer may include at least two polycaprolactone chains attached to a polymeric center block and is functionalized with functional groups that promote the formation of a hydrogel when the aqueous solution is cured with ultraviolet light. The process may also include forming a layer of the aqueous solution on a surface. The process may further include curing the aqueous solution with ultraviolet light to form a solid hydrogel including the copolymer having the salt dispersed therein.

[0057] In some instances, the center block of the polymer can be derived from a naturally occurring biodegradable polymer having at least two free hydroxyl groups.

[0058] In some examples, the polymer center block can include a hydroxyl-bearing polysaccharide, a biodegradable polyester, or a hydroxy fatty acid.

[0059] In some examples, the polymer center block can include polyvinyl alcohol or polybutylene succinate or castor oil.

[0060] In some cases, the aqueous solution may be formed directly on one or both electrodes of the battery before curing.

[0061] In some cases, the hydrogel may be formed at a copolymer loading of 20% or more by weight, based on the total weight of the hydrogel.

[0062] In some examples, the salt may include ammonium chloride (NH4Cl), zinc chloride (ZnCl2), or a mixture thereof.

[0063] In some cases, the salt may be present in the electrolyte at a concentration of at least 0.5M.

[0064] In some cases, the salt may be present in the electrolyte at a concentration of at least 3M and at most 10M.

[0065] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the teachings of the present invention. These and / or other aspects and advantages of embodiments of the present disclosure will become apparent and more readily appreciated from the following description of various embodiments taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0066] [Figure 1] 1 illustrates an exploded view of an exemplary biodegradable electrochemical device in a parallel configuration, according to one or more disclosed embodiments. [Figure 2] FIG. 1 illustrates an exploded view of another exemplary biodegradable electrochemical device in a stacked configuration, according to one or more disclosed embodiments. [Figure 3] 1 shows the 1H NMR spectrum of the PCL-PEG-PCL macromonomer diol after step 1 of the synthetic scheme shown in Scheme 1. [Figure 4] 1 shows the H NMR spectrum of the PCL-PEG-PCL macromonomer diacrylate after step 2 of the synthetic scheme shown in Scheme 1. [Figure 5A] 1 shows stress versus strain curves for PCL-PEG-PCL-based solid aqueous electrolytes produced from PCL-PEG-PCL macromonomers with block chain lengths of 239-20000-239. [Figure 5B] Figure 5A shows the Young's modulus of the PCL-PEG-PCL-based solid aqueous electrolyte for five different measurements across various concentrations of NH4Cl and ZnCl2. [Figure 6] Figure 1 shows a plot of capacity (mAh / cm2) versus cell voltage (V) for an intact MnO2 / Zn electrochemical cell containing a PCL-PEG-PCL based solid aqueous electrolyte and discharged at 0.01 mA / cm2 after resting for 10 hours before discharge. [Figure 7] 1 shows a representative Nyquist plot of Re(Z) vs. Im(Z) monitoring the impedance change during cell discharge for a MnO2 / Zn electrochemical cell containing a PCL-PEG-PCL based solid aqueous electrolyte. [Figure 8] Figure 1 shows a plot of cell voltage (V) versus time (hr) comparing the no-load voltage (OCV) stability of a MnO2 / Zn electrochemical cell containing a PCL-PEG-PCL based solid aqueous electrolyte with a cell containing a liquid aqueous electrolyte. [Figure 9] FIG. 1 shows a plot of capacity (mAh / cm) versus cell voltage (V) comparing the discharge performance of a MnO2 / Zn electrochemical cell containing a PCL-PEG-PCL based solid aqueous electrolyte with a cell containing a liquid aqueous electrolyte. [Figure 10] 1 shows the respective viscosities of the Zn anode paste and the MnO2 paste prepared in Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0067] The following description of various exemplary embodiments is merely exemplary in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0068] The ranges used throughout are used as a shorthand notation to describe any and all values ​​within the range. Any value within the range can be selected as the end of the range. In addition, all references cited herein are incorporated by reference in their entirety. In the event of a conflict between the definitions in this disclosure and those of the cited references, this disclosure shall prevail.

[0069] Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be considered to refer to percentages by weight. The amounts given are based on the active weight of the material.

[0070] Furthermore, all numerical values ​​are indicated as "about" or "approximately" and take into account experimental error and variations that would be expected by one of ordinary skill in the art. It should be recognized that all numerical values ​​and ranges disclosed herein are approximate values ​​and ranges, regardless of whether "about" is also used. It should also be recognized that the term "about," when used in conjunction with a numerical value, refers to a value that may be ±0.01% (inclusive), ±0.1% (inclusive), ±0.5% (inclusive), ±1% (inclusive) of that numerical value, ±2% (inclusive), ±3% (inclusive), ±5% (inclusive), ±10% (inclusive), or ±15% (inclusive) of that numerical value. It should further be recognized that when a numerical range is disclosed herein, any numerical value falling within the range is also specifically disclosed.

[0071] As used herein, the term "or" is an inclusive operator and is equivalent to the term "and / or" unless the context clearly dictates otherwise. The term "based on" is not exclusive and allows for based on additional unrecited factors unless the context clearly dictates otherwise. As used herein, a recitation of "at least one of A, B, and C" includes embodiments containing multiple instances of A, B, or C, A, B, or C, or combinations of A / B, A / C, B / C, A / B / B / B / B / C, A / B / C, etc. Additionally, throughout the specification, the meanings of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on."

[0072] Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same, similar or like parts.

[0073] Biodegradable electrochemical devices are disclosed herein. As used herein, the term "biodegradable" can refer to materials, components, substances, devices, etc. that are capable of or designed to be decomposed by living organisms, particularly microorganisms in landfills, within a reasonable period of time. The materials, components, substances, devices, etc. can be decomposed into water, naturally occurring gases such as carbon dioxide and methane, biomass, or combinations thereof. As used herein, the phrase "biodegradable electrochemical device" or "biodegradable device" can refer to an electrochemical device or device, respectively, at least one or more of whose components are biodegradable. In some cases, a majority or a significant number of the components of a biodegradable electrochemical device or biodegradable device are biodegradable. In other cases, all of the polymeric components of a biodegradable electrochemical device or biodegradable device are biodegradable. For example, while the polymers and / or other organic-based components of an electrochemical device are biodegradable, the inorganic materials of the electrochemical devices disclosed herein, including metals and / or metal oxides, cannot be biodegradable. It should be appreciated that it is generally accepted that if all polymeric and / or organic-based components of an electrochemical device are biodegradable, the entire electrochemical device is considered biodegradable. As used herein, the term or phrase "electrochemical device" can refer to a device that converts electricity into a chemical reaction and / or vice versa. Exemplary electrochemical devices may be or include, but are not limited to, batteries, photosensitized solar cells, electrochemical sensors, electrochromic glass, fuel cells, electrolyzers, etc.

[0074] As used herein, the term or phrase "environmentally friendly electrochemical device" or "environmentally friendly device" can refer to an electrochemical device or device, respectively, that exhibits minimal, lower, or no toxicity to an ecosystem or the general environment. In at least one embodiment, the electrochemical devices and / or components thereof disclosed herein are environmentally friendly.

[0075] In at least one embodiment, the biodegradable electrochemical devices disclosed herein can include an anode, a cathode (i.e., a current collector and / or an active layer), and one or more electrolyte compositions (e.g., a biodegradable solid aqueous electrolyte composition). In another embodiment, the biodegradable electrochemical devices can further include one or more substrates, one or more seals, or a combination thereof.

[0076] The biodegradable electrochemical devices disclosed herein can be flexible. As used herein, the term "flexible" can refer to a material, device, or component thereof that can be bent around a predetermined radius of curvature without breaking and / or cracking. The biodegradable electrochemical devices disclosed herein and / or components thereof can be bent around a radius of curvature of about 30 cm or less, about 20 cm or less, about 10 cm or less, or about 5 cm or less without breaking or cracking.

[0077] 1 illustrates an exploded view of an exemplary biodegradable electrochemical device 100 in a side-by-side or coplanar configuration according to one or more embodiments. As illustrated in FIG. 1 , the biodegradable electrochemical device 100 can include a first substrate 102, a first current collector 104 and a second current collector 106 disposed adjacent to or on the first substrate 102, an anode active layer 108 disposed adjacent to or on the first current collector 104, a cathode active layer 110 disposed adjacent to or on the second current collector 106, an electrolyte layer 112 disposed adjacent to or on the anode active layer 108 and the cathode active layer 110, and a second substrate 114 disposed adjacent to or on the electrolyte composition 112. It should be appreciated that the first current collector 104 and the anode active layer 108 can be collectively referred to herein as an anode 120 of the biodegradable electrochemical device 100. It should be further appreciated that the second current collector 106 and the cathode active layer 110 may be collectively referred to herein as the cathode 122 of the biodegradable electrochemical device 100. As illustrated in Figure 1, the anode 120 and cathode 122 of the biodegradable electrochemical device 100 may be coplanar such that the anode 120 and cathode 122 are disposed along the same XY plane.

[0078] In at least one embodiment, the biodegradable electrochemical device 100 can include one or more seals (two shown: 116, 118) capable of or designed to hermetically seal or hermetically seal the current collectors 104, 106, the anode active layer 108, the cathode active layer 110, and the electrolyte composition 112 between the first substrate 102 and the second substrate 114 of the biodegradable electrochemical device 100. For example, as illustrated in FIG. 1 , the biodegradable electrical device 100 can include two seals 116, 118 inserted between the first substrate 102 and the second substrate 114 and around the current collectors 104, 106, the anode active layer 108, the cathode active layer 110, and the electrolyte composition 112 to hermetically seal or hermetically seal the biodegradable electrochemical device 100. In another embodiment, the biodegradable electrochemical device 100 may not include or may be substantially free of seals 116, 118. For example, the substrates 102, 114 may be fused or bonded together to seal the biodegradable electrochemical device 100.

[0079] 2 illustrates an exploded view of another exemplary biodegradable electrochemical device 200 in a stacked configuration, according to one or more embodiments. As illustrated in FIG. 2, the biodegradable electrochemical device 200 can include a first substrate 202, a first current collector 204 disposed adjacent to or on the first substrate 102, an anode active layer 208 disposed adjacent to or on the first current collector 204, an electrolyte layer 212 disposed adjacent to or on the anode 108, a cathode active layer 210 disposed adjacent to or on the electrolyte composition 212, a second current collector 206 disposed adjacent to or on the cathode active layer 210, and a second substrate 214 disposed adjacent to or on the second current collector 206. It should be appreciated that the first current collector 204 and the anode active layer 208 can be collectively referred to herein as the anode 220 of the biodegradable electrochemical device 200. It should be further appreciated that the second current collector 206 and the cathode active layer 210 may be collectively referred to herein as the cathode 222 of the biodegradable electrochemical device 200. As illustrated in Figure 2, the anode 220 and cathode 222 of the biodegradable electrochemical device 200 may be arranged in a stacked configuration or shape such that the anode 220 and cathode 222 are disposed above or below each other.

[0080] In at least one embodiment, the biodegradable electrochemical device 200 can include one or more seals (two shown: 216, 218) capable of or designed to hermetically seal the current collectors 204, 206, the anode active layer 208, the cathode active layer 210, and the electrolyte composition 212 between the first substrate 202 and the second substrate 214 of the biodegradable electrochemical device 200. For example, as illustrated in FIG. 2 , the biodegradable electrical device 200 can include two seals 216, 218 inserted between the first substrate 202 and the second substrate 214 and around the current collectors 204, 206, the anode active layer 208, the cathode active layer 210, and the electrolyte composition 212 to hermetically seal the biodegradable electrochemical device 200. In another embodiment, the biodegradable electrochemical device 200 may not include or may be substantially free of seals 216, 218. For example, the substrates 202, 214 may be fused or bonded together to seal the biodegradable electrochemical device 200.

[0081] As illustrated in Figures 1 and 2, each of the current collectors 104, 106, 204, 206 can include a respective tab 124, 126, 224, 226 that can extend outside the seal 116, 118, 216, 218 to provide connectivity.

[0082] In at least one embodiment, any one or more of the substrates 102, 114, 202, 214 of each biodegradable electrochemical device 100, 200 may be or include, but are not limited to, a biodegradable substrate. Exemplary biodegradable substrates may be or include, but are not limited to, one or more of polylactic acid (PLA), polylactic-co-glycolic acid (PLGA), silk fibroin, chitosan, polycaprolactone (PCL), polyhydroxybutyrate (PHB), rice paper, cellulose, or combinations or composites thereof.

[0083] The biodegradable substrate of each biodegradable electrochemical device 100, 200 can be stable at temperatures between about 50°C and about 150°C. As used herein, the term "stable" or "stability" can refer to the ability of a substrate to resist dimensional change and maintain structural integrity when exposed to temperatures between about 50°C and about 150°C. For example, the biodegradable substrate can be capable of, or can be designed to maintain, structural integrity with less than about 20%, less than about 15%, or less than about 10% dimensional change after exposure to temperatures between about 50°C and about 150°C. In one example, each of the biodegradable substrates can be stable (e.g., less than 20% dimensional change) at temperatures between about 50°C, about 60°C, about 70°C, about 80°C, about 90°C, about 100°C, or about 110°C to about 120°C, about 130°C, about 140°C, or about 150°C. In another example, each of the biodegradable substrates can be stable at temperatures of at least 100°C, at least 105°C, at least 110°C, at least 115°C, at least 120°C, at least 125°C, at least 130°C, at least 135°C, at least 140°C, or at least 145°C. In at least one embodiment, the biodegradable substrates can be stable at temperatures of about 50°C to about 150°C for a period of about 5 minutes to about 60 minutes or more. For example, the biodegradable substrates can be stable at the above temperatures for a period of about 5 minutes, about 10 minutes, about 20 minutes, or about 30 minutes to about 40 minutes, about 45 minutes, about 50 minutes, about 60 minutes, or more.

[0084] In at least one embodiment, the biodegradable substrates are weldable, bondable, and / or permanently heat-sealable without the use of additional adhesives. For example, the biodegradable substrates of each of the substrates 102, 114, 202, 214 can be weldable and / or bondable to one another without the use of respective seals 116, 118, 216, 218. Exemplary biodegradable substrates that can be weldable and / or bondable to one another can be or include, but are not limited to, thermoplastics such as polylactic acid (PLA), polylactic acid modified with a nucleating agent that enhances crystallinity, e.g., polylactic acid modified with nucleating agent D (PLA-D) and polylactic acid modified with nucleating agent E (PLA-E), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), blends of PLA and polyhydroxybutyrate (PHB), PHB-based blends, etc., or combinations thereof. As used herein, the terms or phrases "bondable," "weldable," and / or "permanently heat sealable" can refer to the ability of a material (e.g., a substrate) to heat seal two surfaces together or permanently join two surfaces together via heating or melting.

[0085] The anode active layer 108, 208 of each biodegradable electrochemical device 100, 200 may be or include one or more of, or combinations and / or alloys of, but not limited to, zinc (Zn), lithium (Li), carbon (C), cadmium (Cd), nickel (Ni), magnesium (Mg), magnesium alloys, zinc alloys, etc. Exemplary anode active layers or materials thereof may be or include, but are not limited to, the like, or combinations thereof. In at least one embodiment, the anode active layer may include zinc oxide (ZnO) in a sufficient amount to regulate or control H gas generation.

[0086] In at least one embodiment, the anode active layer 108, 208 of each of the biodegradable electrochemical devices 100, 200 can be prepared or fabricated from an anode paste. For example, the anode active layer can be prepared from a zinc anode paste. The anode paste can be prepared in an attritor mill. In at least one embodiment, stainless steel shot can be placed in the attritor mill to facilitate the preparation of the anode paste. The anode paste can include one or more metals or metal alloys, one or more organic solvents, one or more styrene-butadiene rubber binders, or combinations thereof. In an exemplary embodiment, the anode paste can include one or more of ethylene glycol, a styrene-butadiene rubber binder, zinc oxide (ZnO), bismuth(III) oxide (BiO), Zn dust, or combinations thereof. Exemplary organic solvents are known in the art and can be or include, but are not limited to, ethylene glycol, acetone, NMP, the like, or combinations thereof. In at least one embodiment, any one or more biodegradable binders may be utilized in place of or in combination with the styrene-butadiene rubber binder.

[0087] The cathode active layer 110, 210 of each of the biodegradable electrochemical devices 100, 200 may be or include one or more of, but are not limited to, iron (Fe), iron (VI) chloride, mercury oxide (HgO), manganese (IV) oxide (MnO), carbon (C), a carbon-containing cathode, gold (Au), molybdenum (Mo), tungsten (W), molybdenum trioxide (MoO), silver oxide (AgO), copper (Cu), vanadium oxide (VO), nickel oxide (NiO), copper iodide (CuI), copper chloride (CuCl), and the like, or combinations and / or alloys thereof. In an exemplary embodiment, the cathode active layer 110, 210 may include manganese (IV) oxide. Carbon and / or carbon-containing cathode active layers can be utilized in aqueous metal-air batteries, such as zinc-air batteries.

[0088] In at least one embodiment, the cathode active layer 110, 210 can include one or more additives capable of or designed to at least partially enhance the electronic conductivity of the cathode active layer 110, 210. Exemplary additives can be or can include, but are not limited to, carbon particles such as graphite, carbon nanotubes, carbon black, or the like, or combinations thereof.

[0089] In at least one embodiment, the cathode active layers 110, 210 of each of the biodegradable electrochemical devices 100, 200 can be prepared or fabricated from a cathode paste. For example, the cathode active layers 110, 210 can be prepared from a manganese (IV) oxide cathode paste. The cathode paste can be prepared in an attritor mill. In at least one embodiment, stainless steel shot can be placed in the attritor mill to facilitate the preparation of the cathode paste. The cathode paste can include one or more metals or metal alloys, one or more organic solvents (e.g., ethylene glycol), one or more styrene-butadiene rubber binders, or combinations thereof. In an exemplary embodiment, the cathode paste can include one or more of ethylene glycol, a styrene-butadiene rubber binder, manganese (IV) oxide (MnO), graphite, or combinations thereof. Exemplary organic solvents are known in the art and can be or include, but are not limited to, ethylene glycol, acetone, NMP, or the like, or combinations thereof. In at least one embodiment, one or more organic solvents may be replaced with or used in combination with an aqueous solvent, such as water. For example, water may be utilized in combination with manganese (IV) oxide.

[0090] The anode and / or cathode paste may have a viscosity of about 100 cP to about 1E6 cP. For example, the anode and / or cathode paste may have a viscosity of about 100 cP or more, about 200 cP or more, about 500 cP or more, about 1,000 cP or more, about 1,500 cP or more, about 2,000 cP or more, about 10,000 cP or more, about 20,000 cP or more, about 50,000 cP or more, about 1E5 cP or more, about 1.5E5 cP or more, about 2E5 cP or more, about 3E5 cP or more, about 4E5 cP or more, about 5E5 cP or more, about 6E5 cP or more, about 7E5 cP or more, about 8E5 cP or more, or about 9E5 cP or more. In another example, the anode and / or cathode paste may have a viscosity of about 200 cP or less, about 500 cP or less, about 1,000 cP or less, about 1,500 cP or less, about 2,000 cP or less, about 10,000 cP or less, about 20,000 cP or less, about 50,000 cP or less, about 1E5 cP or less, about 1.5E5 cP or less, about 2E5 cP or less, about 3E5 cP or less, about 4E5 cP or less, about 5E5 cP or less, about 6E5 cP or less, about 7E5 cP or less, about 8E5 cP or less, about 9E5 cP or less, or about 1E6 cP or less.

[0091] In at least one embodiment, each of the anodes 120, 220 and cathodes 122, 222, or their active layers 108, 110, 208, 210, independently, can comprise a biodegradable binder. The function of the biodegradable binder is to bond together the respective particles of the respective layers and provide adhesion to the subsurface of the substrate, be it the anode current collector 104, 204, the cathode current collector 106, 206, the anode active layer 108, 208, the cathode active layer 110, 210, or a combination thereof. Exemplary biodegradable binders may be or include, but are not limited to, one or more of chitosan, polylactic-co-glycolic acid (PLGA), gelatin, xanthan gum, cellulose acetate butyrate (CAB), polyhydroxybutyrate (PHB), or a combination thereof. In at least one embodiment, any one or more of the biodegradable polymers disclosed herein with respect to the electrolyte compositions can also be utilized as a biodegradable binder for the anode 120, 220, the cathode 122, 222, components thereof, or any combination thereof. As further described herein, one or more biodegradable polymers can be crosslinked. Thus, the biodegradable binder utilized in the anode 120, 220, the cathode 122, 222, and / or components thereof can include a crosslinked biodegradable binder disclosed herein with respect to the electrolyte compositions.

[0092] Each electrolyte layer 112, 212 of each biodegradable electrochemical device 100, 200 may be or include an electrolyte composition. The electrolyte composition may utilize a biodegradable polymer material. The electrolyte composition may be a solid, aqueous electrolyte composition. The solid, aqueous electrolyte composition may be or include a copolymer hydrogel and a salt dispersed in and / or throughout the hydrogel. The copolymer may include at least two polycaprolactone (PCL) chains attached to a polymer center block (CB). For example, the copolymer may be a block copolymer or graft copolymer including at least two PCL chains coupled to a polymer center block, e.g., PCL-CB-PCL. In another example, the copolymer may be a block copolymer or graft copolymer including at least one or more of polylactic acid (PLA), polyglycolic acid (PGA), polyethyleneimine (PEI), or a combination thereof, coupled to a polymer center block.

[0093] The copolymer or solid may be present in the hydrogel in an amount of about 5% to about 90% by weight, based on the total weight of the hydrogel (e.g., the total weight of the solvent, polymer, and salt). For example, the copolymer may be present in an amount of about 5% to about 10% by weight, 15% to about 20% by weight, 25% to about 30% by weight, or 35% by weight or more, based on the total weight of the hydrogel. In another example, the copolymer may be present in an amount of 90% to about 80% by weight, 70% to about 60% by weight, based on the total weight of the hydrogel. In preferred embodiments, the copolymer or solid may be present in the hydrogel in an amount of about 5% to about 60% by weight, about 5% to about 50% by weight, about 20% to about 40% by weight, or about 30% by weight, based on the total weight of the hydrogel. In yet another preferred embodiment, the copolymer or solid may be present in the hydrogel in an amount of more than 30% to about 60% by weight, based on the total weight of the hydrogel.

[0094] The copolymer may be present in the hydrogel in an amount sufficient to provide a continuous film or layer that is free or substantially free of air bubbles. The copolymer may also be present in an amount sufficient to provide a viscosity of about 1,000 cP to about 100,000 cP in the hydrogel. For example, the copolymer may be present in an amount sufficient to provide a viscosity of about 1,000 cP, about 5,000 cP, about 10,000 cP, or about 20,000 cP to about 30,000 cP, about 40,000 cP, about 50,000 cP, about 75,000 cP, about 90,000 cP, or about 100,000 cP in the hydrogel.

[0095] The polymer center block of the copolymer may be a biodegradable polymer, thereby improving or increasing the biodegradability of the solid, aqueous electrolyte composition. The biodegradable polymer of the polymer center block is preferably naturally occurring. The polymer center block may be, include, or be derived from a biodegradable polymer containing at least two free hydroxyl groups available for reaction with a polymer, such as ε-caprolactone. As further described herein, a polymer containing at least two free hydroxyl groups can be reacted with ε-caprolactone to form a copolymer. Exemplary polymers containing at least two free hydroxyl groups that can be used to form the polymer center block (CB) may be or include, but are not limited to, one or more of polyvinyl alcohol (PVA), hydroxyl-bearing polysaccharides, biodegradable polyesters, hydroxy fatty acids (e.g., castor oil), and the like, or combinations thereof. Exemplary hydroxyl-bearing polysaccharides may be or include, but are not limited to, starch, cellulose, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, chitin, guar gum, xanthan gum, agar, pullulan, amylose, alginic acid, dextran, etc., or combinations thereof. Exemplary biodegradable polyesters may be or include, but are not limited to, polylactic acid, polyglycolic acid, polylactic-co-glycolic acid, polyitaconic acid, polybutylene succinate, etc., or combinations thereof. In preferred embodiments, the polymer center block may be or include one or more of polyvinyl alcohol (PVA), a hydroxyl-bearing polysaccharide, a biodegradable polyester, or a hydroxy fatty acid.

[0096] In at least one embodiment, the polymer center block of the copolymer can be a biodegradable polymer, for example, the polymer center block of the copolymer can be or include, but is not limited to, polyethylene glycol (PEG), a hydroxy-terminated polyester, a hydroxyl-terminated polyolefin, such as hydroxy-terminated polybutadiene, or a combination thereof.

[0097] A copolymer comprising at least two polycaprolactone (PCL) chains attached to a polymer center block may be a graft copolymer or a block copolymer. Whether a copolymer is a graft copolymer or a block copolymer can be determined, at least in part, by the number and / or arrangement of the at least two free hydroxyl groups of the polymer center block. For example, reacting ε-caprolactone with a polymer center block having hydroxyl groups on the monomers along the length of the polymer center block chain forms a graft copolymer. In another example, reacting ε-caprolactone with a polymer center block having hydroxyl groups at each end of the polymer center block forms a block copolymer. Exemplary block copolymers may be or include triblock copolymers, tetrablock copolymers, star block copolymers, or combinations thereof.

[0098] As discussed above, the electrolyte composition may be a solid, aqueous electrolyte composition comprising a copolymer hydrogel and a salt dispersed in the hydrogel. The salt of the hydrogel may be or include any suitable ionic salt known in the art. Exemplary ionic salts may be or include, but are not limited to, one or more of organic-based salts, inorganic-based salts, room temperature ionic liquids, deep eutectic solvent-based salts, and the like, or combinations or mixtures thereof. In a preferred embodiment, the salt is or includes a salt usable in zinc / manganese(IV) oxide (Zn / MnO) electrochemistry. Exemplary salts may be or include, but are not limited to, zinc chloride (ZnCl), ammonium chloride (NH4Cl), sodium chloride (NaCl), phosphate buffered saline (PBS), sodium sulfate (Na2SO4), zinc sulfate (ZnSO4), manganese sulfate (MnSO4), magnesium chloride (MgCl2), calcium chloride (CaCl2), ferric chloride (FeCl3), lithium hexafluorophosphate (LiPF6), potassium hydroxide (KOH), sodium hydroxide (NaOH), etc., or combinations thereof. In preferred embodiments, the salt of the electrolyte composition may be or include ammonium chloride (NH4Cl), zinc chloride (ZnCl2), or combinations or mixtures thereof. In another embodiment, the salt may be or include an alkali metal salt, such as sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), potassium hydroxide (KOH), or combinations or mixtures thereof.

[0099] The salt may be present in an amount capable of providing ionic conductivity, an amount designed to provide ionic conductivity, or an amount sufficient to provide ionic conductivity. For example, the salt may be present in the hydrogel in an amount or concentration of at least 0.1 M, more preferably at least 0.5 M, even more preferably at least 2 M, and even more preferably at least 4 M. The salt may be present in the hydrogel at a concentration of 10 M or less, more preferably 6 M or less. In another example, the salt may be present in the hydrogel in an amount of about 3 M to about 10 M, about 4 M to about 10 M, about 5 M to about 9 M, or about 6 M to about 8 M. In an exemplary implementation, the salt included ammonium chloride and zinc chloride. In this case, the ammonium chloride was present in an amount of about 2.5 M to about 3 M, about 2.8 M to about 2.9 M, or about 2.89 M, and the zinc chloride was present in an amount of about 0.5 M to 1.5 M, about 0.8 M to about 1.2 M, or about 0.9 M.

[0100] In at least one embodiment, the electrolyte composition can include one or more additives. The one or more additives can be or include, but are not limited to, biodegradable or environmentally friendly nanomaterials. The biodegradable nanomaterials can be capable of providing and / or improving the structural strength of the electrolyte layer or its electrolyte composition without sacrificing its flexibility. Exemplary biodegradable nanomaterials of additives can be or include, but are not limited to, polysaccharide-based nanomaterials, inorganic nanomaterials, etc., or combinations thereof. Exemplary polysaccharide-based nanomaterials can be or include, but are not limited to, one or more of cellulose nanocrystals, chitin nanocrystals, chitosan nanocrystals, starch nanocrystals, etc., or combinations or mixtures thereof. Exemplary inorganic nanomaterials can be or include, but are not limited to, one or more of silicon oxide (e.g., fumed silica), aluminum oxide, layered silicates, or lime, or combinations or mixtures thereof. Exemplary layered silicates may be or may include, but are not limited to, one or more of bentonite, kaolinite, dickite, nacrite, attapulgite, illite, halloysite, montmorillonite, hectorite, fluorohectorite, nontronite, beidellite, saponite, volkonskoite, magadiite, medmontite, kenyaite, sauconite, muscovite, vermiculite, mica, hydromica, phengite, brahmarite, celadonite, or combinations or mixtures thereof.

[0101] The one or more additives may be present in an amount of at least 0.1% by weight, based on the total weight of the hydrogel. For example, the one or more additives may be present in an amount of at least 0.1%, at least 0.5%, or at least 1% by weight, based on the total weight of the hydrogel. The one or more additives may also be present in an amount of 40% by weight or less, based on the total weight of the hydrogel. For example, the one or more additives may be present in an amount of 40% by weight or less, 20% by weight or less, or 10% by weight or less, based on the total weight of the hydrogel.

[0102] In at least one embodiment, the electrolyte composition can include an aqueous solvent. For example, the electrolyte composition can include water. In at least one embodiment, the electrolyte composition can include a co-solvent. For example, the electrolyte composition can include water and an additional solvent. Exemplary co-solvents can be or include, but are not limited to, one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, or combinations thereof. The co-solvent can include water in an amount greater than about 20%, greater than about 30%, greater than about 40%, greater than about 50% to about 60%, greater than about 70%, greater than about 80%, greater than about 85%, or greater than about 90% by weight or volume of the aqueous solvent of the electrolyte composition.

[0103] In at least one embodiment, the electrolyte composition comprises a copolymer hydrogel, a salt dispersed in the hydrogel, a solvent (e.g., water or water and a cosolvent), one or more photoinitiators, any one or more additives, or a combination thereof. For example, the electrolyte composition comprises a copolymer hydrogel, a salt dispersed in the hydrogel, a solvent, one or more additives, or a combination or mixture thereof. In at least one embodiment, the electrolyte composition consists of or consists essentially of a copolymer hydrogel, a salt dispersed in the hydrogel, and a solvent (e.g., water or water and a cosolvent). In another embodiment, the electrolyte composition consists of or consists essentially of a copolymer hydrogel, a salt dispersed in the hydrogel, a solvent, and one or more additives. The solvent, which may be water or a combination of water and a cosolvent, can provide an equilibrium state for the hydrogel.

[0104] A solid, aqueous electrolyte composition can be produced according to Scheme (1): Step 1: [ka] Step 2: [ka] Step 3: [ka]

[0105] Step 1 of Scheme (1) involves the synthesis of ε-caprolactone 1 and a polymer center block (CB(OH)) containing at least two free hydroxyl groups. x ) 2 in the presence of a catalyst (i.e., a photoinitiator). x The ring-opening polymerization of 2 is (PCL) x-CB macromonomer 3, where x can be an integer greater than or equal to 2. It should be appreciated that any suitable ring-opening polymerization catalyst can be utilized in Step 1. In at least one example, the catalyst can be or include a tin catalyst, such as tin 2-ethylhexanoate.

[0106] The ring-opening polymerization of Step 1 is typically carried out or can be carried out at an elevated temperature for a suitable period of time. In at least one embodiment, the ring-opening polymerization can be carried out at a temperature of about 50° C. to about 200° C., more preferably at a temperature of about 100° C. to about 150° C. The ring-opening polymerization can be carried out for a period of about 5 hours to about 48 hours, more preferably about 24 hours.

[0107] (PCL) x The -CB macromonomer 3 can be purified by a generally known method. For example, (PCL) x -CB macromonomer 3 can be purified by extraction, precipitation, and filtration. Purification can be repeated one or more times to provide a relatively pure product. In at least one embodiment, the PCL chain of macromonomer 3 has or contains a free hydroxyl group. (PCL) x The free hydroxyl groups of -CB macromonomer 3 may be available for functionalization.

[0108] Step 2 of scheme (1) uses functionalizing agent (FM)4 to prepare (PCL) x -CB macromonomer 3 was functionalized to obtain functionalized macromonomer (FG-PCL). x The method may include a step of forming -CB5. Exemplary functionalizing agents (FM) may be or include, but are not limited to, acryloyl chloride, methacryloyl chloride, methacrylic anhydride, maleic anhydride, or combinations or mixtures thereof. The functionalizing agent (FM) may be a functionalized macromonomer (FG-PCL). x To generate -CB5, the functional group (FG) was added to (PCL) xThe functional groups may be capable of being introduced, appended, or otherwise added to the -CB macromonomer 3, or may be designed to be so. Exemplary functional groups may be or may include, but are not limited to, one or more of acrylate, vinyl ether, allyl ether, alkene, alkyne, thiol, or a combination thereof. Functionalized Macromonomer (FG-PCL) x -(PCL) for generating CB5 x Functionalization of -CB macromonomer 3 yields functionalized macromonomer (FG-PCL). x When an aqueous solution of -CB5 is crosslinked with radiant energy, for example, ultraviolet light, it promotes the formation of a hydrogel.

[0109] Functionalized macromonomer (FG-PCL) x (PCL) with functionalizing agent (FM)4 to generate -CB5 x The functionalization of -CB macromonomer 3 can be carried out or carried out in a solvent in the presence of a base. The base can be or include an amine, such as trimethylamine or triethylamine. The solvent can be or include a polar aprotic solvent, such as dichloromethane. The functionalization can be carried out under an inert atmosphere. For example, the functionalization can be carried out under an inert gas, nitrogen, argon, etc. The functionalization can be carried out under heating to promote the reaction. For example, the reaction can be carried out at a temperature of up to about 60°C. Functionalized Macromonomer (FG-PCL) x -CB5 can be purified by commonly known methods (e.g., extraction, precipitation, and filtration).

[0110] Step 3 of scheme (1) is the reaction of the functionalized macromonomer (FG-PCL) in an aqueous solvent or medium. xThe method may include mixing, combining, or otherwise contacting the -CB5, salt 6, and photoinitiator 7 together to prepare an aqueous solution. Step 3 may also include irradiating the aqueous solution with radiant energy, e.g., ultraviolet (UV) light, to crosslink the aqueous solution and form a solid aqueous electrolyte in the form of a hydrogel 8.

[0111] Functionalized macromonomer (FG-PCL) x The aqueous solution prepared by contacting -CB5, salt 6, and photoinitiator 7 with one another can be disposed on a substrate or a surface thereof before irradiating the aqueous solution with radiant energy. For example, the aqueous solution can be coated, cast, or printed (e.g., via a printing process) onto the substrate or its surface to prepare or form a layer of the aqueous solution on the substrate or its surface. In a preferred embodiment, the layer of the aqueous solution is printed onto the substrate via a printing process or method to form the electrolyte layer 112, 212. As further described herein, the layer of the aqueous solution can be printed directly onto adjacent one or both of the anode active layer 108, 208 and / or cathode active layer 110, 210 of the biodegradable electrochemical device 100, 200 to form the respective electrolyte layer 112, 212. In at least one embodiment, the aqueous solution can include one or more ink additives to facilitate or assist the printing process.

[0112] Photoinitiator 7 may be a UV crosslinking photoinitiator. Photoinitiator 7 may be water-soluble. Exemplary photoinitiators 7 may be or include, but are not limited to, lithium acylphosphinate or lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate (LAP), IRGACURE™ 2959, DAROCUR™ 1173, sodium 4-[2-(4-morpholino)benzoyl-2-dimethylamino]-butylbenzenesulfonate (MBS), monoacylphosphine oxide (MAPO) salts Na-TPO and Li-TPO, bisacylphosphine oxide salts Na-BAPO, Li-BAPO, thioxanthone derivatives, benzophenone derivatives, IRGACURE™ 754, PEG-modified BAPO, or combinations thereof. In a preferred embodiment, the photoinitiator 7 utilized is or includes lithium acylphosphinate (LAP). This is because LAP is water soluble, non-cytotoxic, and does not require an inert atmosphere.

[0113] Crosslinking of the aqueous solution using radiant energy can be performed at room temperature. Crosslinking of the aqueous solution using radiant energy can also be performed without an inert atmosphere. Crosslinking of the aqueous solution can include exposing the aqueous solution to ultraviolet light at a sufficient and / or appropriate wavelength and power. It should be recognized that the wavelength of the ultraviolet light can depend, at least in part, on the activation wavelength of the photoinitiator 7. In at least one embodiment, the activation wavelength of the photoinitiator 7 can be from about 250 nm to about 500 nm. It should be further recognized that the power of the ultraviolet light can at least in part determine the cure time of the aqueous solution. For example, increasing the power of the ultraviolet light can decrease the cure time of the aqueous solution. Exposing the aqueous solution to ultraviolet light for a period of less than 60 minutes (min) may be required to form a hydrogel. In preferred embodiments, the aqueous solution is exposed to ultraviolet light for about 30 minutes or less, more preferably about 20 minutes or less, and even more preferably about 10 minutes or less. In some embodiments, the aqueous solution is crosslinked for a period of about 10 milliseconds (ms) to about 100 ms. Thus, the power of the ultraviolet light can be varied to provide adequate, sufficient, or complete crosslinking of the aqueous solution in a desired period of time. The hydrogels produced by cross-linking the aqueous solutions can be used "as is." For example, the hydrogels produced by cross-linking the aqueous solutions can be used as the electrolyte layers 112, 212 of the biodegradable electrochemical devices 100, 200, respectively.

[0114] As previously discussed, the electrolyte layer 112, 212 of each of the biodegradable electrochemical devices 100, 200 may be or include a solid, aqueous electrolyte composition. The solid, aqueous electrolyte composition can have sufficient mechanical and electrochemical properties required for commercially available or commercially useful printed batteries. For example, the solid, aqueous electrolyte composition can have a Young's modulus or storage modulus greater than about 0.10 megapascals (MPa), greater than about 0.15 MPa, or greater than about 0.20 MPa, thereby providing a solid, aqueous electrolyte composition with sufficient strength while maintaining sufficient flexibility to prevent fracture under stress. The solid, aqueous electrolyte composition can have a Young's modulus of about 100 MPa or less, about 80 MPa or less, about 60 MPa or less, or even lower.

[0115] As used herein, the term or phrase "yield strength" can refer to the maximum stress a material can undergo or withstand before it begins to permanently deform. The solid, aqueous electrolyte composition can have a yield strength of about 5 kPa or greater. For example, the solid, aqueous electrolyte composition can have a yield strength of about 5 kPa or greater, about 8 kPa or greater, about 10 kPa or greater, about 12 kPa or greater, about 15 kPa or greater, or about 20 kPa or greater.

[0116] The solid, aqueous electrolyte composition can be electrochemically stable with respect to both the anode active layer 108, 208 and the cathode active layer 110, 210, respectively, of the biodegradable electrochemical devices 100, 200. For example, the solid, aqueous electrolyte composition can maintain a stable no-load voltage over an extended period of time, thereby demonstrating electrochemical stability with respect to both the anode active layer 108, 208 and the cathode active layer 110, 210, respectively, of the biodegradable electrochemical devices 100, 200. In at least one embodiment, the solid, aqueous electrolyte composition can be electrochemically stable in contact with the electrode layers for at least one month, at least two months, at least three months, at least four months, at least five months, at least six months, at least one year, or longer.

[0117] The solid, aqueous electrolyte compositions disclosed herein can be utilized in any electrochemical device, such as electrochemical cells, batteries, and / or the biodegradable electrochemical devices disclosed herein 100, 200. In a preferred embodiment, the solid, aqueous electrolyte compositions can be utilized in batteries including a Zn anode active layer and a MnO2 cathode active layer.

[0118] Each current collector 104, 106, 204, 206 of the biodegradable electrochemical devices 100, 200 may be capable of, or may be designed to, receive, conduct, and deliver electricity. Exemplary current collectors 104, 106, 204, 206 may be or include, but are not limited to, silver, e.g., silver microparticles and silver nanoparticles, carbon, e.g., carbon black, graphite, carbon fiber, carbon nanoparticles, e.g., carbon nanotubes, graphene, reduced graphene oxide (RGO), etc., or any combination thereof.

[0119] method Embodiments of the present disclosure may provide a method for fabricating an electrochemical device, such as the biodegradable electrochemical device 100, 200 disclosed herein. The method may include providing a biodegradable substrate. The method may also include depositing an electrode and / or electrode composition adjacent to or on the biodegradable substrate. Depositing the electrode may include depositing and drying a current collector for the electrode and depositing and drying an active layer (i.e., an anode or cathode material) adjacent to or on the current collector. The method may also include drying the electrode and / or electrode composition. The electrode composition may be dried thermally (e.g., by heating). The method may also include depositing a biodegradable, radiation-curable electrolyte composition on or adjacent to the electrode composition. The method may further include radiation-curing the biodegradable, radiation-curable electrolyte composition. The biodegradable, radiation-curable electrolyte composition may be cured by radiation before or after drying the electrode composition. The biodegradable substrate may be thermally compatible with any thermal drying method. For example, the biodegradable substrate can be dimensionally stable (e.g., free from bending and / or curling) when thermally dried. The method can include depositing a second electrode and / or electrode composition on or adjacent to the biodegradable, radiation-curable electrolyte composition. In at least one embodiment, each of the first and second electrode compositions is a metal foil composition. The metal foil composition of the first electrode can be different from the metal foil composition of the second electrode.

[0120] In at least one embodiment, the electrochemical device, all of its components, or substantially all of its components are fabricated via a printing process. The printing process can include depositing, stamping, spraying, sputtering, jetting, coating, layering, etc. For example, one or more current collectors, one or more electrode compositions, a biodegradable, radiation-curable electrolyte composition, or a combination thereof can be deposited via a printing process. Exemplary printing processes may be or may include, but are not limited to, one or more of the following, or a combination thereof: screen printing, inkjet printing, flexographic printing (e.g., stamping), gravure printing, offset printing, airbrushing, aerosol printing, typesetting, roll-to-roll processes, etc. In a preferred embodiment, the components of the electrochemical device are printed via screen printing.

[0121] In at least one embodiment, radiation-curing the biodegradable, radiation-curable electrolyte composition includes exposing the electrolyte composition to radiant energy. The radiant energy can be ultraviolet light. Exposing the biodegradable, radiation-curable electrolyte composition to radiant energy can at least partially crosslink the biodegradable, radiation-curable electrolyte composition, thereby forming a hydrogel. The biodegradable, radiation-curable electrolyte composition can be cured by radiation at room temperature. In at least one embodiment, the biodegradable, radiation-curable electrolyte composition is cured in an inert atmosphere. For example, the biodegradable, radiation-curable electrolyte composition can be cured under nitrogen, argon, etc. In another embodiment, the biodegradable, radiation-curable electrolyte composition can be cured under a non-inert atmosphere.

[0122] In at least one embodiment, the biodegradable, radiation-curable electrolyte composition can be radiation-cured in a period of about 5 ms to about 100 ms. For example, the biodegradable, radiation-curable electrolyte composition can be radiation-cured in a period of about 5 ms, about 10 ms, about 15 ms, about 20 ms, about 30 ms, about 40 ms, or about 50 ms to about 60 ms, about 70 ms, about 80 ms, about 85 ms, about 90 ms, about 95 ms, or about 100 ms. The period of time sufficient to radiation-cure the biodegradable, radiation-curable electrolyte composition can be determined at least in part by the power of the ultraviolet light.

[0123] In at least one embodiment, the method can also include depositing an adhesive, e.g., a biodegradable adhesive, to obtain the sealed portions 116, 118, 216, 218 of the biodegradable electrochemical devices 100, 200, respectively. For example, the method can include depositing a layer of adhesive to couple the substrates or portions of the substrates of the electrochemical devices (e.g., peripheral areas of the tabs 124, 126, 224, 226) to one another. In some embodiments, the adhesive can be a hot melt adhesive. In other embodiments, the electrochemical device can be free or substantially free of any adhesive. For example, the biodegradable substrate can be weldable and / or heat sealable without the use of an additional adhesive.

[0124] In at least one embodiment, the biodegradable substrate may be a continuous web or may be supported by a continuous web. As used herein, the term "web" may refer to a moving support surface, such as a conveyor belt. In at least one example, multiple electrochemical devices are printed simultaneously as separate or linked elements or components on a continuous web. For example, each component of multiple electrochemical devices may be printed simultaneously as separate or linked elements on a continuous web as an array in a parallel process. As used herein, the term or phrase "linked element" or "linked component" may refer to each element or component of an electrochemical device that is physically adjacent to, overlaps, or otherwise in contact with one another. Exemplary linked elements may be or include an active layer (e.g., a cathode active layer or an anode active layer) adjacent to or disposed on a current collector layer, a current collector layer and copper tape tab, or an electrolyte layer on an active cathode / anode layer.

[0125] Embodiments of the present disclosure may provide a method for fabricating, producing, or otherwise synthesizing a solid aqueous electrolyte. The method may include dissolving a salt and a functionalized copolymer in an aqueous solution to prepare an aqueous mixture. The functionalized copolymer may include at least two polycaprolactone (PCL) chains attached or coupled to a polymer center block. The functionalized copolymer may be functionalized with any suitable functional group that promotes or facilitates the formation of a hydrogel when the aqueous mixture is exposed to or cured by radiant energy, such as ultraviolet light. The method may also include forming a layer of the aqueous mixture on a surface. The surface may be an anode and / or cathode of a battery. The method may further include crosslinking the aqueous solution with radiant energy in the form of ultraviolet light to form a solid aqueous electrolyte, which may be a solid hydrogel including the functionalized copolymer and a salt dispersed in the functionalized copolymer. [Example]

[0126] The examples and other implementations described herein are exemplary and are not intended to limit the full scope of the compositions and methods of the present disclosure. Equivalent changes, modifications, and variations of the specific implementations, materials, compositions, and methods can be made within the scope of the present disclosure and will produce substantially similar results.

[0127] Example 1 Exemplary solid, aqueous electrolyte compositions were prepared. Specifically, PCL-PEG-PCL-based solid, aqueous electrolytes were prepared by synthesizing a PCL-PEG-PCL macromonomer, synthesizing a PCL-PEG-PCL acrylate, and subsequently utilizing the PCL-PEG-PCL acrylate to form a solid, aqueous electrolyte.

[0128] The process or reaction illustrated in Scheme 2 was adapted from Xu et al. (Xu, C., Lee, W., Dai, G., and Hong, Y. ACS Appl. Mater. Interfaces 2018, 10, 12, 9969-9979), the contents of which are incorporated herein only to the extent consistent with this disclosure, to synthesize PCL-PEG-PCL macromonomers.

[0129] [ka]

[0130] Specifically, approximately 5 g of ε-caprolactone, approximately 21.9 g of polyethylene glycol (PEG; MW=20,000 Da), and approximately 34.8 mg of tin 2-ethylhexanoate catalyst were combined, mixed, or otherwise contacted together in a round-bottom flask and stirred with a magnetic stir bar. The round-bottom flask was purged and filled with nitrogen three times, then heated to approximately 120°C with stirring for approximately 24 hours to prepare a reaction mixture. The reaction mixture was cooled to room temperature, dissolved in dichloromethane (CHCl), and the crude product was precipitated in cold anhydrous diethyl ether. 1 The H NMR is shown in Figure 3. As shown in Figure 3, the crude product synthesized from the initial precipitation of the macromonomer from diethyl ether resulted in the presence of unreacted ε-caprolactone. To remove or separate the unreacted ε-caprolactone, the crude product was dissolved in approximately 50 mL of dichloromethane at room temperature. Approximately 200 mL of diethyl ether was added dropwise at room temperature over a minimum period of approximately 1 hour to prepare a suspension. The suspension was stirred overnight at room temperature and filtered through a Buchner funnel. The resulting solid was dried overnight in a vacuum oven maintained at room temperature. As shown in Figure 4, 1 The precipitation was repeated until the peaks due to ε-caprolactone were no longer observed in the 1 H NMR spectrum.

[0131] The above process was repeated utilizing various amounts of polyethylene glycol, thereby synthesizing various macromonomers or macromonomer formulations with various ratios of polycaprolactone (PCL) to polyethylene glycol (PEG), as summarized in Table 1. 1 H NMR spectra were used to determine the respective block chain lengths of each PCL-PEG-PCL macromonomer formulation.

[0132] [Table 1]

[0133] The process or reaction illustrated in Scheme 3 was adapted from Xu et al. (Xu, C., Lee, W., Dai, G., and Hong, Y. ACS Appl. Mater. Interfaces 2018, 10, 12, 9969-9979), the contents of which are incorporated herein to the extent consistent with this disclosure, for the synthesis of PCL-PEG-PCL acrylate.

[0134] [ka]

[0135] Specifically, approximately 5 g of PCL-PEG-PCL macromer was dissolved in approximately 15 mL of dichloromethane, and approximately 0.6 mL of triethylamine was added to the mixture while stirring for approximately 30 minutes in an ice bath under nitrogen. A solution containing approximately 0.33 mL of acryloyl chloride and approximately 15 mL of dichloromethane was added dropwise to the reaction mixture over 30 minutes, causing the solution to turn yellow. The solution was then heated at approximately 40° C. for approximately 24 hours under nitrogen. After heating, the reaction mixture was subsequently cooled to room temperature, and the product was precipitated by the dropwise addition of diethyl ether. 1 The presence of vinylic protons in the 1 H NMR spectrum confirmed the formation of PCL-PEG-PCL acrylate.

[0136] To produce a solid, aqueous electrolyte, i.e., PCL-PEG-PCL hydrogel solid aqueous electrolyte, approximately 400 mg of PCL-PEG-PCL acrylate (Formulation C in Table 1) and approximately 2.5 mg of lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) were dissolved in 1 mL of a 4 M aqueous solution of ammonium chloride (NH4Cl / HO). It should be noted that the molarity of the ammonium chloride may be varied from approximately 0.5 M to approximately 6 M without any changes or modifications in the synthesis / process. The resulting solution was allowed to settle to remove air bubbles, but the solution was not degassed with nitrogen. The pH of the solution was between approximately 3 and 4. The resulting solution was uniformly distributed on a 25 x 75 x 1 mm glass microscope slide taped to a glass plate. The solution was exposed to a DYMAX™ Bluewave 200 (wavelength approximately 300 to approximately 450 nm) for approximately 10 minutes, providing approximately 8 mW / cm2 of light to the solution. 2 The solution was irradiated with radiation, thereby forming a hydrogel.

[0137] The hydrogel was yellow and contained dispersed ammonium chloride. The hydrogel was also flexible and could be stretched without breaking. Analysis of the hydrogel indicated that it could be dried and rehydrated, and the rehydrated hydrogel maintained its flexibility. It was discovered that stable, solid hydrogels could not be produced when PCL-PEG-PCL acrylate was present in an amount / concentration below about 10 wt%. In other words, it was surprisingly and unexpectedly discovered that the amount of PCL-PEG-PCL acrylate required to prepare stable, solid hydrogels was about 20 wt% or greater.

[0138] Example 2 The mechanical properties of the PCL-PEG-PCL hydrogel solid aqueous electrolyte prepared from Formulation C in Example 1 were evaluated. Standard compression testing using an INSTRON™ 5548 microtester was used to obtain stress versus strain curves over five separate measurements per sample. Young's modulus represents the sample's ability to withstand deformation, which can also be referred to as robustness. The Young's modulus for five separate measurements across various concentrations of ammonium chloride and zinc chloride are summarized in Figures 5A and 5B. As shown in Figures 5A and 5B, the hydrogel exhibited a Young's modulus of over 0.3 MPa, which is sufficient for use as a solid gel polymer electrolyte in batteries. It should be noted that the hydrogel exhibits sufficient mechanical properties for use as a separator between battery electrodes or for application. The results further demonstrate that salt concentrations from about 0.5 M to about 6 M have no effect on the mechanical properties of the hydrogel, as no significant differences in the measured Young's modulus were observed with varying salt molarity, as shown in Figure 5B.

[0139] Example 3 The electrochemical properties of the PCL-PEG-PCL hydrogel solid aqueous electrolyte prepared from Formulation C in Example 1 were evaluated. In particular, electrolyte stability on the surface of metallic zinc was evaluated. Normally, zinc surfaces corrode over time when in contact with aqueous solutions, thereby generating zinc oxide and zinc hydroxide. These zinc oxide and hydroxide migrate into the electrolyte, basifying the pH. It should be recognized that the migration and basification of oxides and hydroxides into the electrolyte can result in or produce the precipitation of diamine chlorides or chlorinated zincates from ammonium chloride or zinc chloride. These precipitates can saturate the electrolyte, leading to a decrease or loss of conductivity in the solid aqueous electrolyte.

[0140] To evaluate electrolyte stability, the PCL-PEG-PCL hydrogel solid aqueous electrolyte prepared from Formulation C in Example 1 was placed in direct contact with a zinc surface for one week. After one week, corrosion of the zinc surface to zinc oxide was observed. However, zinc oxide formation was minimal. Furthermore, it was surprisingly and unexpectedly discovered that the hydrogel body was free of any salt precipitates, indicating that zinc surface passivation had occurred, the interface between the zinc surface and the solid electrolyte had reached a steady state, and no further corrosion occurred. Therefore, it was demonstrated that the PCL-PEG-PCL hydrogel solid aqueous electrolyte exhibits sufficient corrosion resistance for use as a polymer electrolyte in zinc-based batteries or systems.

[0141] Example 4 Various batteries were fabricated and evaluated using the PCL-PEG-PCL hydrogel solid aqueous electrolyte prepared from Formulation C in Example 1. Zinc was used as the anode and manganese oxide / carbon was used as the cathode. To fabricate the batteries, the PCL-PEG-PCL hydrogel solid aqueous electrolyte was placed between the anode and cathode. The PCL-PEG-PCL hydrogel solid aqueous electrolyte was used as both the separator and electrolyte. After a 10-hour rest period, each battery delivered 0.01 mA / cm. 2 The electrochemical performance of the cell was evaluated by continuously discharging it at 1000 kJ / s, monitoring the cell voltage during discharge, and measuring the cell capacity at the end of discharge. A typical discharge curve for the cell is shown in Figure 6. The associated changes in the cell's resistance during various stages of discharge are shown in Figure 7, which is a Nyquist plot obtained from electrochemical impedance spectroscopy measurements.

[0142] As shown in Figure 6, the cell has a current of 0.01 mA / cm 2It exhibited a relatively small overpotential of approximately 100 mV upon application of current and further exhibited a sloping discharge curve typical of aqueous MnO2 / Zn cells. As shown in Figure 7, the frequency response plotted as Re(Z) vs. -Im(Z) showed only a slight change in solution resistance over time and a very slight change in charge transfer resistance, thereby demonstrating the stability of the PCL-PEG-PCL hydrogel solid aqueous electrolyte during discharge. Thus, the preceding description demonstrated its stability both within itself and during cell discharge, as well as its stability relative to both the Zn and MnO2 electrodes.

[0143] Example 5 The no-load voltage (OCV) stability of the battery prepared in Example 4 was evaluated and compared to cells containing a liquid aqueous electrolyte. Solid-state aqueous cells were fabricated in the same manner as in Example 1. For comparison with the liquid aqueous electrolyte, the same salt concentrations were dissolved in Milli-Q low-resistivity water (>18 MΩ.cm). A glass fiber separator was immersed in this freshly prepared electrolyte and placed between the anode and cathode. Both the solid-state and liquid-based cells were allowed to stand at room temperature, and the OCV of the cells was continuously monitored over a specified period of time using a potentiostat / galvanostat. The OCV stability of the battery and cells utilizing the liquid aqueous electrolyte is shown in Figure 8.

[0144] As shown in Figure 8, the battery prepared in Example 4 exhibited voltage stability over a period of approximately 120 hours. As further shown in Figure 8, the voltage stability of the battery prepared in Example 4 was at least as good as that of cells utilizing a liquid aqueous electrolyte.

[0145] Example 6 The discharge performance of the battery prepared in Example 4 was evaluated and compared with that of a cell containing a liquid aqueous electrolyte. In particular, to compare the discharge performance, the capacity (mAh / cm 2 ) was measured versus voltage (V). After resting at OCV for 24 hours, the cell was charged at 0.06 mA / cm 2The cell was discharged at 0.5 V. The cell discharge was considered complete when the cell voltage reached 0.5 V. The cathode utilized consisted of a MnO2 active layer deposited on a carbon-based current collector, and the anode utilized consisted of a Zn active layer deposited on a silver-based current collector. The voltage was referenced to the Zn anode. The discharge performance is summarized in Figure 9.

[0146] As shown in Figure 9, the discharge performance of the MnO2 / Zn electrochemical cell containing a PCL-PEG-PCL-based solid aqueous electrolyte with 4 M NH4Cl was at least as good as the cell containing a liquid aqueous electrolyte with the same salt at the same concentration.

[0147] Example 7 An exemplary biodegradable electrochemical device, specifically a biodegradable electrochemical cell, was prepared by preparing an anode paste, preparing a cathode paste, printing electrodes for the biodegradable electrochemical device, preparing an electrolyte macromonomer, preparing and printing a curable electrolyte ink, and assembling the biodegradable electrochemical device.

[0148] To prepare the anode paste, i.e., zinc (Zn) anode paste, an attritor mill equipped with a 75 mL stainless steel attritor was charged with approximately 150 g of approximately 3 mm stainless steel shot, approximately 16.1 g of ethylene glycol, approximately 5.0 g of styrene-butadiene rubber (SBR) binder commercially available from MTI Corporation, Richmond, CA, approximately 8.3 g of zinc oxide (ZnO), approximately 12.2 g of bismuth(III) oxide (BiO), and approximately 78.3 g of Zn dust. The attritor mill was operated until the Zn anode paste had the consistency of a creamy paste. The Zn anode paste was then separated from the shot and transferred to a sealed container to prevent evaporation of the ethylene glycol.

[0149] To prepare the cathode paste, i.e., manganese dioxide (MnO2) cathode paste, an attritor fitted with a 75 mL stainless steel attritor was loaded with approximately 150 g of approximately 3 mm stainless steel shot, approximately 21 g of ethylene glycol, approximately 1 g of styrene-butadiene rubber (SBR) binder, approximately 30 g of manganese(IV) oxide (MnO2), and approximately 7.6 g of graphite. The attritor mill was operated until the MnO2 cathode paste had the consistency of a creamy paste. The MnO2 cathode paste was then separated from the shot and transferred to a sealed container to prevent evaporation of the ethylene glycol.

[0150] The viscosity of each Zn anode paste and MnO2 cathode paste was evaluated using the shear sweep method to determine their rheological properties. The viscosities of each Zn anode paste and MnO2 cathode paste are summarized in Figure 10. Both the anode and cathode pastes exhibited non-Newtonian shear thinning behavior consistent with screen-printable paste inks. Particle size was observed to have no significant effect on ink viscosity.

[0151] Electrodes for biodegradable electrochemical devices were prepared via printing. Specifically, silver paste ink (DUPONT® 5025) or carbon paste ink (CI-2042; NAGASE AMERICA, LLC.) was screen-printed onto a PLA-D substrate using a 180-mesh nylon screen with an 80-durometer squeegee to prepare the respective current collectors. The screen-printed current collectors were then dried for approximately 9 minutes in a forced air oven maintained at approximately 120°C to remove or evaporate the solvent contained in the paste ink and dry the paste ink. The dried current collectors had a thickness of approximately 6 μm.

[0152] Zn electrodes were prepared by depositing a Zn anode layer adjacent to each current collector containing the previously prepared Zn anode paste. Specifically, the Zn anode paste was screen-printed onto the current collector using an 80-mesh nylon screen with an 80-durometer squeegee, followed by drying in a hot air oven at about 120°C for about 9 minutes to remove or evaporate the solvent contained in the paste. The dried Zn electrodes had a thickness of about 40 μm.

[0153] MnO2 electrodes were prepared by depositing a cathode active layer adjacent to each current collector with the previously prepared MnO2 cathode paste. Specifically, the MnO2 cathode paste was screen-printed onto the current collector using an 80-mesh nylon screen with an 80-durometer squeegee, followed by drying in a hot air oven at approximately 120°C for approximately 9 minutes to remove or evaporate the solvent contained in the paste. The dried MnO2 electrodes had a thickness of approximately 40 μm.

[0154] Screen printing of MnO2 and Zn pastes to prepare electrodes was observed to show efficient wetting on the substrate with no evidence of pinhole formation.

[0155] To prepare the electrolyte macromonomers, PCL-PEG-PCL diol and PCL-PEG20-PCL-diacrylate were prepared.

[0156] To prepare the curable electrolyte ink, about 39.4 g of ZnCl, about 4.87 g of NH4Cl, about 80 g of water, and about 20 g of ethylene glycol were combined to form about 2.9 M ZnCl 2、An electrolyte solution containing about 0.9 M NH4Cl and about 20 wt% ethylene glycol was prepared. About 6 g of the electrolyte solution was then combined with about 2 g of the macromonomer and allowed to soak overnight without mixing to facilitate dissolution. About 0.5 g of a stock solution of lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate (LAP) was combined with about 10 g of the electrolyte solution and about 20 drops of BYK-24 silicone defoamer additive (commercially available from BYK-CHEMIS GMBH of Wesel, Germany) to prepare a curable electrolyte ink.

[0157] The electrolyte layer was prepared by depositing a curable electrolyte ink adjacent to the Zn electrode via screen printing. Using a 60-mesh screen and an 80-durometer squeegee, the curable electrolyte ink was screen-printed adjacent to the Zn electrode. The curable electrolyte layer was then cured under a 14 W, 395 nm LED lamp for approximately 500 ms to form a gel-like electrolyte layer with a thickness of approximately 15 μm.

[0158] Another electrolyte layer was similarly produced by depositing a curable electrolyte ink adjacent to the MnO2 cathode via screen printing. Using a 60-mesh screen and an 80-durometer squeegee, the curable electrolyte ink was screen-printed adjacent to the MnO2 cathode. The curable electrolyte layer was then cured under a 14-W, 395-nm LED lamp for approximately 500 ms to form a gel-like electrolyte layer with a thickness of approximately 15 μm.

[0159] To fabricate or assemble a biodegradable electrochemical device, a Zn electrode, including a gel electrolyte layer, a Zn layer, and a current collector layer, was arranged in a stacked orientation and placed on an MnO electrode, including a gel electrolyte layer, an MnO layer, and a current collector layer. The Zn and MnO electrodes were oriented so that their respective electrolyte layers faced each other. Light pressure was applied using a roller to promote intimate contact between the respective electrolyte layers of the Zn and MnO electrodes, creating an unsealed biodegradable electrochemical device.

[0160] The unsealed biodegradable electrochemical device was then placed between 80 μm sheets of polyimide film (KAPTON®, commercially available from DuPont of Wilmington, Del.) to protect the substrate from destructive melting during the subsequent sealing step. Heat sealing of the device with a die maintained at approximately 170° C. was used to heat seal the edges of the stacked electrodes of the biodegradable electrochemical device. The sealed biodegradable electrochemical device was removed from the polyimide film and allowed to cool.

[0161] Example 8 The no-load voltage across the exposed tab of the biodegradable electrochemical device prepared in Example 7 was measured to be 1.46 volts using a digital multimeter.

[0162] Example 9 Exemplary solid, aqueous electrolyte compositions containing a biodegradable central block were prepared. Specifically, PVA-PCL-based solid, aqueous electrolytes were prepared by synthesizing PVA-PCL macromonomers.

[0163] To synthesize PVA-PCL macromonomer, the process or reaction shown in Scheme 3 was introduced.

[0164] Step 1: [ka] Step 2: [ka]

[0165] Specifically, approximately 10 g of poly(vinyl alcohol) (average MW = 3000 g / mol) was placed in a round-bottom flash oven equipped with a magnetic stirrer and condenser. The solid was dried under vacuum for approximately 2 hours. Approximately 20 mL of dimethyl sulfoxide was added, and the resulting mixture was heated with stirring at approximately 80°C until complete solubilization. Once solubilized, the temperature was cooled to approximately 40°C, and approximately 186 μL of ε-caprolactone and approximately 175 μL of tin(II)(2-ethylhexanoate)2 were added. The reaction mixture was heated at approximately 100°C for approximately 24 hours. After heating, the reaction mixture was allowed to cool to approximately 40°C. Approximately 30 mL of water was added, and the resulting free-flowing solution was poured into approximately 500 mL of acetone with stirring to form a suspension. The resulting suspension was centrifuged for approximately 10 minutes, and the resulting pellet was redispersed in acetone and centrifuged twice under the same conditions. The resulting solid was dried under vacuum overnight. Approximately 6.7 g of PVA-PCL block was produced, which was a yellow solid.

[0166] Approximately 6.7 g of the PVA-PCL block was combined with approximately 200 mL of N,N-dimethylformamide (DMF) in a round-bottom flask equipped with a magnetic stirrer and a condenser and heated at approximately 60°C until complete solubilization. An additional aliquot of DMF was added to facilitate solubilization. The solubilized reaction mixture was then allowed to cool to approximately 10°C, and approximately 1.94 mL of trimethylamine was added. Approximately 1.94 mL of acryloyl chloride was added dropwise to the reaction mixture, which was then heated at approximately 40°C for approximately 24 hours. The reaction mixture was then poured into acetone to form a large pellet of the product. The pellet was dried under vacuum overnight, thereby producing approximately 1.6 g of PVA-PCL acrylate.

[0167] Example 10 Various biodegradable substrates were evaluated. Specifically, the biodegradable biopolyester substrates listed in Table 2 were extruded into sheets using an extruder equipped with a 20 cm wide flat die. Each sheet was then calendered between two rollers. Separate films of polylactic acid-based blends were also 3D printed to achieve different surface qualities. Portions of the sheets were annealed to enhance crystallization and improve temperature resistance.

[0168] The temperature resistance of each of the sheets was evaluated by placing them on a flat metal plate in an oven at a temperature of about 120°C or about 150°C. Specifically, each of the sheets was placed on a flat surface in an oven maintained at the specified temperature for about 10 minutes. After heating, dimensional stability (e.g., flatness and uniformity) was evaluated. To pass dimensional stability, each sheet had to demonstrate no deformation. The results of the oven test are summarized in Table 2.

[0169] In addition to evaluating the dimensional stability of each biodegradable substrate, compatibility and adhesion with the ink were also evaluated. To evaluate the compatibility and adhesion of the ink to each substrate, the previously prepared carbon-based and silver-based inks were screen-printed onto each biodegradable substrate and evaluated for adhesion. Dimensional stability was also evaluated after drying at approximately 120°C. To pass the ink adhesion evaluation, the ink must maintain adhesion to the substrate while (1) bending at an angle of approximately 45°C and (2) swabbing across the entire surface. To pass dimensional stability after drying at approximately 120°C, each sheet had to demonstrate no deformation (e.g., maintain flatness and uniformity) after drying for 10 minutes at 120°C. The results are summarized in Table 2.

[0170] [Table 2]

[0171] As shown in Table 2, each of the substrates evaluated passed the 120°C oven test, except for molten PBAT. As further shown in Table 2, each of the substrates passed the 150°C oven test, except for PBAT and PBS. Also shown in Table 2, the majority of the substrates exhibited thermal instability during the ink drying process.

[0172] The present disclosure has been described with reference to exemplary implementations. While a limited number of implementations have been shown and described, those skilled in the art will recognize that modifications can be made in these implementations without departing from the principles and spirit of the foregoing detailed description. It is intended that all such modifications and alterations be construed as included in the present disclosure insofar as they come within the scope of the appended claims or equivalents thereof.

Claims

1. a first substrate; a second substrate; an anode disposed between the first substrate and the second substrate; a cathode disposed between the first substrate and the second substrate; and 1. An electrochemical device comprising an electrolyte composition disposed between an anode and a cathode, the electrolyte composition comprising a cross-linked biodegradable polymeric material that is radiation-curable prior to being cross-linked; An electrochemical device, wherein the first substrate and the second substrate comprise one or more biodegradable substrates.

2. 10. The electrochemical device of claim 1, wherein the biodegradable polymeric material before being crosslinked comprises radiation-curable functional groups comprising one or more of an acrylate, a vinyl ether, an allyl ether, an alkene, an alkyne, a thiol, or a combination thereof.

3. 10. The electrochemical device of claim 1, wherein the electrolyte composition is derived from a radiation-curable electrolyte precursor composition that includes at least one photoinitiator.

4. the one or more biodegradable substrates are stable up to 120°C; the one or more biodegradable substrates maintain their structural integrity with less than 10% dimensional change after exposure to 120°C; and / or 10. The electrochemical device of claim 1, wherein the one or more biodegradable substrates comprise one or more of polylactic acid (PLA), polylactic-co-glycolic acid (PLGA), silk fibroin, chitosan, polycaprolactone (PCL), polyhydroxybutyrate (PHB), rice paper, cellulose, or a combination or composite thereof.

5. 10. The electrochemical device of claim 1, wherein the electrolyte composition comprises a hydrogel, the hydrogel comprising water and a cross-linked biodegradable polymeric material.

6. the anode comprises one or more of Zn, Li, C, Mg, an Mg alloy, a Zn alloy, or a combination thereof; and / or The cathode is Fe, MnO 2 ,C,Au,Mo,W,MoO 3 , Ag 2 10. The electrochemical device of claim 1, comprising one or more of O, Cu, or a combination thereof.

7. the anode comprises a first biodegradable binder; and The electrochemical device of claim 1 , wherein the cathode comprises a second biodegradable binder.

8. the cathode and anode are arranged in a stacked configuration, or 8. The electrochemical device of claim 7, wherein the cathode and anode are arranged in a lateral XY planar configuration.

9. 8. The electrochemical device of claim 7, wherein the first or second biodegradable binder comprises one or more of chitosan, polylactic-co-glycolic acid (PLGA), cellulose acetate butyrate (CAB), polyhydroxybutyrate (PHB), or a combination thereof.

10. providing a biodegradable substrate; depositing an electrode composition onto a biodegradable substrate and thermally drying the electrode composition; depositing a biodegradable radiation curable electrolyte composition onto the electrode composition; and radiation curing the biodegradable, radiation-curable electrolyte composition after thermal drying of the electrode composition.

10. A process for fabricating an electrochemical device, comprising:

11. the electrode composition is a metal foil composition; 11. The process for fabricating an electrochemical device of claim 10 further comprising depositing a second electrode composition onto the biodegradable radiation curable electrolyte composition.

12. 1. A biodegradable solid aqueous electrolyte composition comprising a copolymer hydrogel and a salt dispersed in the hydrogel, wherein the copolymer comprises at least two polycaprolactone chains attached to a polymer center block.

13. the polymer center block is derived from a naturally occurring biodegradable polymer having at least two free hydroxyl groups; the polymer center block comprises a hydroxyl-bearing polysaccharide, a biodegradable polyester, or a hydroxy fatty acid; or 13. The electrolyte composition of claim 12, wherein the polymer center block comprises polyvinyl alcohol or polybutylene succinate or castor oil.

14. further comprising a nanomaterial additive; 13. The electrolyte composition of claim 12, wherein the nanomaterial additive comprises cellulose nanocrystals, chitin nanocrystals, chitosan nanocrystals, starch nanocrystals, silicon oxide, aluminum oxide, layered silicates, lime, or any mixture thereof.

15. further comprising water and a co-solvent; 13. The electrolyte composition of claim 12, wherein the co-solvent comprises one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, or combinations thereof.

16. anode, cathode, and 13. An electrochemical device comprising the biodegradable solid aqueous electrolyte composition of claim 12, wherein the biodegradable solid aqueous electrolyte composition is disposed between an anode and a cathode.

17. 1. A process for producing a solid aqueous electrolyte, comprising: dissolving a salt and a functionalized copolymer in an aqueous solution, the copolymer comprising at least two polycaprolactone chains attached to a polymeric center block and functionalized with functional groups that promote the formation of a hydrogel when the aqueous solution is cured with ultraviolet light; forming a layer of an aqueous solution on a surface; and curing the aqueous solution with ultraviolet light to form a solid hydrogel comprising the copolymer having the salt dispersed therein. The process includes:

18. the polymer center block is derived from a naturally occurring biodegradable polymer having at least two free hydroxyl groups; the polymer center block comprises a hydroxyl-bearing polysaccharide, biodegradable polyester, or hydroxy fatty acid; or 18. The process of claim 17, wherein the polymer center block comprises polyvinyl alcohol or polybutylene succinate or castor oil.

19. 20. The process of claim 17, wherein the layer of aqueous solution is formed directly on one or both electrodes of a battery before curing.

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