Zn-air rechargeable battery

Abstract

The invention relates to a novel Zn-air rechargeable battery with a carbon / graphite cathode and a dicarboxy-telechelic poly(ethylene glycol) containing additives such as PEG or poloxamer. The synthesized dicarboxy-telechelic PEG was successfully applied to suppress the formation of dendritic and mossy deposits on the Zn electrode surface. The weight of the electrode did not change after long-term testing.

Description

Technical Field

[0001] This invention relates to a novel Zn-air rechargeable battery having a carbon / graphite cathode and a dicarboxylated telechelic polyethylene glycol containing additives (e.g., PEG or poloxamer). The synthesized dicarboxylated telechelic PEG was successfully applied to suppress the formation of dendritic and moss-like deposits on the surface of the zinc electrode. The weight of the electrode remained unchanged after long-term testing. Background Technology

[0002] The storage and utilization of renewable energy is crucial for building a sustainable society. To this end, efficient and long-life batteries should be developed to achieve proper energy storage. To date, the most commonly used and popular energy storage devices appear to be lithium-ion batteries used in electric vehicles and other electronic devices [1]. However, the use of these batteries has some limitations, such as their insufficient energy density, lack of high capacity due to safety concerns, and very limited availability of Li [2,3]. Recently, various metal-air batteries have been developed due to their high energy density properties [4-8]. Among these batteries, rechargeable zinc-air batteries have become the focus of research [9-11]. One of the main advantages of zinc-air batteries over those based on Li-ions is that, unlike lithium, zinc is an abundant element in the Earth's crust, and oxygen can be obtained directly from the air. Other advantages of zinc-air batteries are their high energy density (1350 Wh / kg), and the aqueous electrolyte provides safe operating conditions for high-capacity rechargeable batteries. The charge rate of these batteries can be achieved by developing bifunctional cathodes that can promote both the oxygen evolution reaction (OER, for charging) and the oxygen reduction reaction (ORR, for discharging)[9]. Interestingly, in some cases, different electrodes are used for the charging and discharging processes (using different catalysts)[12-15], while other developed bifunctional cathodes use only one electrode to provide both reactions[16-19]. However, developing catalysts with high OER activity appears to be a major challenge; in addition, controlling the morphology of deposited zinc during charging is also a frequent problem[20-23]. The morphology of zinc deposition depends largely on the operating conditions, for example, moss-like structures form at low current densities. Furthermore, layered deposition may occur at increasing current densities (at medium densities), while zinc dendrite formation is expected at high current densities. Therefore, the morphology of the zinc electrode surface can be controlled by appropriate charging schemes

[24] . On the other hand, some studies have indicated that this harmful dendrite formation can be prevented by adding different additives to the electrolyte. For example, trimethyloctadecylammonium chloride (STAC)

[20] , tetrabutylammonium bromide

[25] , or nickel and indium

[26] dissolved in the electrolyte have been shown to inhibit dendrite formation. It has also been shown that the use of fluorinated surfactants can reduce mossy zinc deposition

[28] .

[0003] Banik and Akolkar used low molecular weight poly(ethylene glycol-diol) (PEG200) for this purpose and reported a model that predicted an order-of-magnitude decrease in the growth rate of zinc dendrites in the presence of high concentrations of PEG (10,000 ppm), which is consistent with experimental results

[27] .

[0004] Based on the literature, it can be concluded that there is still a need to construct rechargeable Zn-air batteries that can reduce deposit formation and avoid ZnO precipitation on the surface of Zn electrodes. Summary of the Invention

[0005] This invention relates to a rechargeable Zn-air alkaline battery having a carbon-based air cathode and a zinc anode, wherein the alkaline battery comprises a dicarboxylated telechelic polymer of C2-C3 alkylene glycol units (subunits or monomer units), preferably comprising a dicarboxylated telechelic polymer containing ethylene oxide units.

[0006] The present invention also relates to a rechargeable Zn-air alkaline battery having a carbon-based air cathode and a zinc anode, the alkaline battery comprising a dicarboxylated telechelic polymer containing ethylene oxide units.

[0007] Preferably, the dicarboxylated telechelic polymer is used as an additive in the battery electrolyte.

[0008] Preferably, the dicarboxylated telechelic polymer reduces the rate of charge transfer processes.

[0009] Preferably, the dicarboxylated telechelic polymer reduces (preferably avoids) the formation of dendritic deposits and / or other types of deposits on the Zn electrode.

[0010] Preferably, the poly(alkylene glycol) according to the present invention has a molecular weight (preferably average molecular weight) of not more than 3500 Da, more preferably not more than 2000 Da, and more preferably not more than 1000 Da.

[0011] The additive preferably chelates Zn(II) ions. Preferably, Zn-polyalkylene glycol (COO)2 reduces the rate of charge transfer and is preferably adsorbed on the surface of the Zn electrode.

[0012] Specifically, the dicarboxylated telechelicerlic polymer refers to an α,ω-dicarboxylated polymer comprising C2-C3 alkylene glycol subunits, wherein the monomers of the polymer are selected from 1,2-ethylene glycol, 1,2-propanediol, and 1,3-propanediol. Preferably, at least a portion of the subunits is an ethylene-diol subunit. Preferably, at least 10% (w / w), at least 20% (w / w), more preferably at least 30% (w / w), or particularly at least 40% (w / w) of the dicarboxylated telechelicerlic polymer consists of ethylene-diol subunits.

[0013] In a preferred embodiment, the dicarboxylated telechelic polymer is dicarboxylated telechelic PEG (α,ω-dicarboxy-poly(ethylene glycol)).

[0014] The preferred dicarboxylated telechelic PEG has a molecular weight of no more than 3300 Da, and more preferably no more than 1500 Da.

[0015] In some embodiments, dicarboxylated telechelicer PEG 600 is omitted. In some embodiments, dicarboxylated telechelicer PEG, particularly dicarboxymethyl ether (PEG BCME), is omitted.

[0016] In a preferred embodiment, the molecular weight of the dicarboxylated telechelic PEG is at least 100 Da or at least 200 Da.

[0017] In a preferred embodiment, the molecular weight of the dicarboxylated telechelic PEG is 100 to 1400 Da, preferably 200 to 1000 Da, particularly 300 to 900 Da, more preferably 400 to 800 Da or 200 to 600 Da, especially preferably about 600 Da, for example 500 to 700 Da.

[0018] In another preferred embodiment, the dicarboxylated telechelicerum is an α,ω-dicarboxylated-poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) copolymer (poloxam). Preferably, at least 10% (w / w), at least 20% (w / w), more preferably at least 30% (w / w), or particularly at least 40% (w / w) of the dicarboxylated telechelicerum consists of ethylene glycol subunits.

[0019] In a specific embodiment, the propylene glycol content in poloxamer is 30-70% w / w, preferably 40-60% w / w, and highly preferably about 50% w / w.

[0020] The molecular weight of the poloxamer is preferably not higher than 5000 Da, and more preferably about 1800 Da.

[0021] In a preferred embodiment of the rechargeable Zn-air alkaline battery, the cathode is (essentially) composed of graphite and carbon.

[0022] Preferably, the battery has an initial cell potential of 1.2V to 1.6V, preferably 1.25V.

[0023] In a particularly preferred embodiment, in a rechargeable Zn-air alkaline battery, cellophane (i.e., regenerated cellulose) is used as a semipermeable membrane, i.e., a separator (or diaphragm).

[0024] In a preferred embodiment, the electrolyte of the battery contains an alkaline hydroxide solution (preferably a potassium hydroxide solution) and the dicarboxylated telechelic poly(alkylene glycol) of the present invention as an additive.

[0025] In a preferred embodiment, the battery electrolyte contains only KOH and [Zn(OH)4]. 2- And the non-toxic dicarboxylated telechelic PEG additive. In a preferred embodiment, the battery has an initial battery volume potential of 1.2V to 1.6V, preferably 1.25V.

[0026] Preferably, in a rechargeable Zn-air alkaline battery, polyethylene and cotton form the electrode framework.

[0027] i) In a preferred embodiment, in a rechargeable Zn-air alkaline battery

[0028] The anode includes a Zn plate.

[0029] The air cathode comprises, or is composed of, graphite and carbon.

[0030] The separator is a semi-permeable membrane made of regenerated cellulose (celluloid), and

[0031] The electrolyte consists of KOH and [Zn(OH)4]. 2- And as an additive, non-toxic dicarboxylated telechelic poly(alkylene glycol).

[0032] Preferably, in the initial stage of the battery, the concentration of KOH is 2 to 10 M, more preferably about 6 M, and [Zn(OH)4] 2- The concentration is 0.1 to 0.5 M, preferably 0.25 M.

[0033] In a preferred embodiment, the initial battery body potential is 1.2V to 1.6V, preferably 1.25V. During normal operation, the battery does not produce H2 gas.

[0034] ii) In a preferred embodiment, in a rechargeable Zn-air alkaline battery

[0035] The anode includes a Zn plate.

[0036] The air cathode comprises, or is composed of, graphite and carbon.

[0037] The separator is a semi-permeable membrane made of regenerated cellulose (celluloid), and

[0038] The electrolyte consists of KOH and [Zn(OH)4]. 2- And non-toxic dicarboxylated telechelic PEG additives.

[0039] Preferably, KOH and [Zn(OH)4] are present in the electrolyte. 2- The concentration is as defined in paragraph i).

[0040] Preferably, the concentration of the non-toxic dicarboxylated telechelic PEG additive is 50 to 500 ppm, more preferably 50 to 190 ppm, and especially 80 to 160 ppm.

[0041] Preferably, the concentration of the non-toxic dicarboxylated telechelic PEG additive is 0.5 × 10⁻⁶. -4 Up to 5×10 -4 M, preferably 1×10 -4 Up to 3×10 -4 M, especially 1.5×10 -4 Up to 2.5×10 -4 M.

[0042] Preferably, the dicarboxylated telechelic PEG is 300 to 900 Da, more preferably 400 to 800 Da, or particularly preferably 200 to 500 Da, or 200 to 600 Da, or about 600 Da, for example 500 to 700 Da.

[0043] iii) In a preferred embodiment, in a rechargeable Zn-air alkaline battery

[0044] The anode includes a Zn plate.

[0045] The air cathode comprises, or is composed of, graphite and carbon.

[0046] The separator is a semi-permeable membrane made of regenerated cellulose (celluloid), and

[0047] The electrolyte consists of KOH and [Zn(OH)4]. 2- And as an additive, a non-toxic dicarboxylated telechelic dicarboxylated-poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) copolymer.

[0048] Preferably, in the electrolyte, KOH and [Zn(OH)4] 2- The concentration is as defined in paragraph i).

[0049] Preferably, the concentration of the non-toxic dicarboxylated telechelic poly(ethylene glycol)-poly(propylene glycol) copolymer (preferably dicarboxylated telechelic poloxamer) additive is 0.5 × 10⁻⁶. -4 Up to 5×10 -4 M, preferably 1×10 -4 Up to 3×10 -4 M, especially 1.5×10 -4 Up to 2.5×10 -4 M. The preferred copolymer has a value of 300 to 2000 Da, more preferably 300 to 1500 Da or 500 to 1800 Da.

[0050] In a preferred embodiment, the battery electrolyte contains only KOH and [Zn(OH)4]. 2- The cathode is composed of graphite and carbon, with celluloid used as a semi-permeable membrane (i.e., a separator), and the cathode skeleton preferably contains polyethylene and cotton, wherein the cell has an initial cell volume potential of 1.2V to 1.6V, preferably 1.25V.

[0051] In a preferred embodiment, the battery has a rectangular cell.

[0052] In a preferred embodiment of the rechargeable Zn-air alkaline battery, the carbon-based air cathode comprises a graphite body. In a particular embodiment, in cathode 20, the graphite body 21 is a graphite rod, and the carbon 22 is activated carbon. In a particular embodiment, anode 10 comprises a Zn plate 11. At least during battery operation, wires 60 are connected to the cathode and anode.

[0053] In one set of embodiments, the present invention relates to the following:

[0054] 1. The present invention relates to a rechargeable Zn-air alkaline battery having a carbon-based air cathode and a zinc anode, said alkaline battery comprising a dicarboxylated telechelic polymer containing ethylene oxide units.

[0055] 2. The rechargeable Zn-air alkaline battery according to claim 1, wherein the dicarboxylated telechelic polymer is dicarboxylated telechelic PEG (α,ω-dicarboxylated poly(ethylene glycol)) used as an additive in the electrolyte of the battery, wherein, preferably, the molecular weight of the dicarboxylated telechelic PEG is not higher than 3300 Da, and more preferably not higher than 1500 Da.

[0056] 3. The rechargeable Zn-air alkaline battery according to claim 2, wherein the dicarboxylated telechelic PEG has a molecular weight of about 3300 Da, about 1500 Da, or about 600 Da, preferably about 600 Da.

[0057] 4. The rechargeable Zn-air alkaline battery according to claim 1, wherein the dicarboxylated telechelic polymer is polyethylene glycol-polypropylene glycol-polyethylene glycol (poloxam), preferably, the molecular weight of the poloxamer is not higher than 5000 Da, and more preferably about 1800 Da.

[0058] 5. The rechargeable Zn-air alkaline battery according to claim 4, wherein the poloxamer contains propylene glycol at a content of 30-70% w / w, preferably 40-60% w / w, and highly preferably about 50% w / w.

[0059] 6. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 5, wherein the cathode is composed of graphite and carbon.

[0060] 7. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 6, wherein celluloid is used as a semi-permeable membrane, i.e., a separator.

[0061] 8. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 7, wherein the electrolyte of the battery contains only KOH and [Zn(OH)4]. 2- And the non-toxic dicarboxylated telechelic PEG additive.

[0062] 9. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 8, wherein the battery has a rectangular battery body.

[0063] 10. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 8, wherein the battery has an initial battery potential of 1.2V to 1.6V, preferably 1.25V.

[0064] Preferably, in a rechargeable Zn-air alkaline battery, polyethylene and cotton form the electrode framework.

[0065] definition

[0066] In this document, "dicarboxylated telechelicer polymer" refers to a dicarboxylated polymer. According to the present invention, the dicarboxylated telechelicer polymer comprises C2-C3 alkylene glycol subunits.

[0067] Poly(alkylene glycol) polymers herein refer to polymers of alkylene glycol monomers, particularly polymers of 1,2-ethylene glycol, 1,2-propanediol, and / or 1,3-propanediol obtained by water-free polycondensation. In this document, poly(alkylene glycol), poly(epoxide), polyalkylene glycol, or poly(epoxide) are used interchangeably with necessary modifications, and similar alternative names may also be applied to poly(ethylene glycol) and poly(propylene glycol).

[0068] Poly(alkylene glycol) (or polyalkylene glycol, which can be used interchangeably) polymers can be homopolymers of a single type of alkylene glycol subunit or copolymers of more than one type of alkylene glycol subunit. In particular, the poly(alkylene glycol) polymers contain ethylene glycol and / or propylene glycol subunits, preferably at least ethylene glycol subunits. Suitable PAGs include polyethylene glycol (PEG), and copolymers of ethylene glycol and propylene glycol (e.g., poloxamer, meroxapols); for example, surfactants)

[0069] In certain embodiments, poly(alkylene glycol), preferably “PEG” or “poly(ethylene glycol)”, or copolymers of ethylene glycol and propylene glycol as used herein, is intended to include any water-soluble poly(alkylene glycol).

[0070] The end groups and structure of the poly(alkylene glycol) polymer (preferably poly(ethylene glycol) comprising the polymer of the present invention) are carboxylic acid ester groups.

[0071] In the case of poly(alkylene glycols) (e.g., under the name PEG), the numbers typically included indicate their average molecular weight (e.g., a PEG with n=9 has an average molecular weight of about 400 Daltons and will be labeled PEG400). Most PEGs consist of molecules with a molecular weight distribution (i.e., they are polydisperse).

[0072] As used herein, “molecular weight” refers to the average molecular weight (or “molecular weight”) of the polymer, which is typically determined by any suitable method, such as size exclusion chromatography or light scattering techniques, or by mass spectrometry or any other suitable method. Size distribution can be determined by weight-average molecular weight (M). w ) or number-average molecular weight (M n Statistically, the ratio is called the polydispersity index.

[0073] As used in this article, “electrolyte” refers to a substance that causes current conduction due to the presence of positively and negatively charged ions that can migrate in the electrolyte, wherein the preferred electrolyte is a solution in which ion migration occurs at the negative and positive terminals (cathode and anode) of the circuit, respectively.

[0074] In this paper, "separator" is used as a permeation membrane placed between the anode and cathode of the battery.

[0075] As used in this specification, the singular forms “a,” “an,” and “the” include the plural forms, unless the context clearly indicates otherwise.

[0076] The terms “comprises” or “comprising” (replaced by the alternative “including”) are hereby interpreted as having a non-exhaustive meaning and allowing for the addition or insertion of additional features, method steps, or components to anything that includes the listed features or method steps or components. The term “consisting of” herein refers to a list of features or method steps or components that is exhaustive and does not allow for the inclusion of additional components. However, those skilled in the art will understand from the technical description that the apparatus or method may include additional features that may be necessary for operation under certain conditions; however, this is not a genuine advantage of the inventive concept, and therefore, as a teaching, “consisting of” herein may be modified to “substantially constitutes” without adding any new content.

[0077] The phrases “substantially constitute” or “substantially comprise” should be understood to mean that the product consists of the mandatory features, method steps, or components listed, such as in the claims, while allowing for the additional inclusion of other features, method steps, or components that do not substantially affect the essential characteristics of the use, method, composition, or other subject matter. It should be understood that, if necessary, “comprising” or “including” can be replaced herein by “substantially constitute” or “substantially comprise” without adding new substances. Attached Figure Description

[0078] Figure 1. MALDI-TOF mass spectra of dicarboxylated teleclaw PEG1500. The main series corresponds to sulfonated dicarboxylated teleclaw polyethylene glycol. The inset shows two additional series appearing in the mass spectrum. The numbers at the tops of these peaks indicate the measured and theoretical m / z values ​​(for the main series, these are shown in parentheses). Potassium salts of dicarboxylated teleclaw PEG ionized by potassium ions are represented by series A, while series B corresponds to potassium-ionized monocarboxylated PEG.

[0079] Figure 2. Arrangement and drawing of a rectangular Zn-air rechargeable battery: side view ( Figure 2a ), Top view ( Figure 2b )

[0080] Figure 3a Long-term discharge of a cylindrical galvanic cell. The red solid line represents the curve fitted using the stretching exponential function (Equation 1).

[0081] Figure 3a Photo of a rectangular Zn-air rechargeable battery

[0082] Figure 4 Charging and discharging of cylindrical rechargeable batteries. Charging steps at 7.5 mA / cm. -2 It operates at a current density of 0.625 mA / cm². -2Before the second charging step, add dicarboxylated telechelicer PEG (Mn: 1500 Da, 2 × 10⁻⁶). -4 M). (The illustration shows a real-time image of the zinc electrode.)

[0083] Figure 5. In the absence of dicarboxylated telechelic PEG additives ( Figure 5a ) and contains dicarboxylated telechelic PEG additive (Mn: 600Da) Figure 5b ), contains dicarboxylated telechelic PEG additive (Mn: 600Da) Figure 5c ), contains dicarboxylated telechelic PEG additive (Mn: 600Da) Figure 5d The cyclic voltammetry curves for the first cycle are shown in the following case. In each case, the additive concentration was 2 mM, and the solution contained 6 M KOH and 0.25 M ZnO. The scan rate was 20 mV / s. -1 .

[0084] Figure 6. Cyclic test of a rectangular Zn-air secondary battery. The current density remains constant (i.e., 2 mA / cm²). -2 The charging and discharging time limit is set to 5 minutes.

[0085] Figure 6.1 Cyclic testing of a rectangular Zn-air secondary battery without additives.

[0086] Figure 6.2 Cyclic testing of a rectangular Zn-air secondary battery with PEG-(COOH)2 having a molecular weight of Mn = 600 Da.

[0087] Figure 6.3 Cyclic testing of a rectangular Zn-air secondary battery with PEG-(COOH)2 having a molecular weight of Mn = 1500 Da.

[0088] Figure 6.4 Cyclic testing of a rectangular Zn-air secondary battery with PEG-(COOH)2 having a molecular weight of Mn = 3300 Da.

[0089] Figure 7 During the cyclic testing, the discharge of the rectangular Zn-air rechargeable battery was compared with and without the dicarboxylated telechelicer PEG additive: (a) without the dicarboxylated telechelicer PEG additive, (b) with the dicarboxylated telechelicer PEG600, (c) with the PEG1500, and (d) with the PEG3300. The solid black line represents the curve fitted by Equation 1. Experimental conditions: See Figure 6. Textual description.

[0090] Figure 8 Long-term cycle performance (E) of rectangular Zn-air rechargeable batteries with dicarboxylated telechelic PEG600 additive电池 (Capacity and coulombic efficiency). Current density is 2 mA / cm². -2 The charging and discharging time limits are each set to 5 minutes.

[0091] Figure 9 Using a current density of 2 mA / cm² -2 SEM images of zinc electrodes after 68 hours of cycling performance testing with additive-free zinc electrodes containing carboxyl telechelic PEG600, PEG1500 and PEG3300 respectively.

[0092] Figure 10 EDS spectra of zinc electrodes after 68-hour cycle performance testing with dicarboxylated telechelic PEG600 additive.

[0093] Figure 11. Photograph of the experimental battery - essentially the same as that using dicarboxylated telechelicerlic PEG600 additive.

[0094] Figure 12 Charge-discharge test of batteries containing the additive dicarboxylic acid telechelic poloxamer ( Figure 12 a). Magnified view of the charge-discharge cycle ( Figure 12 b). Battery coulombic efficiency after 270 cycles ( Figure 12c ).

[0095] Figure 13. Battery removed from the battery pack after 270 charge-discharge cycles. Figure 13b ), Zn anode surface 270 in the battery body Figure 13a Battery body. Detailed Implementation

[0096] We can distinguish three fundamental processes that occur on and near the surface of the Zn electrode (i.e., in the electrical double layer of the Zn electrode) during recharging: (i) dissociation of the Zn-complex to obtain Zn 2+ (ii) Charge transfer processes to neutralize Zn 2 + (iii) Introduce zinc metal into the lattice of the Zn electrode to form metallic Zn.

[0097] If the charge transfer process is much faster than the introduction of the formed metallic Zn into the lattice of the Zn electrode, deposits are expected to form on the surface of the Zn electrode. Therefore, to avoid deposit formation, the conditions for slowing down the charge transfer process must be fundamentally defined; that is, the charge transfer process should be the rate-determining step in the entire recharging process.

[0098] The dicarboxylic acid telechelic poly(alkylene glycol) used in the battery of the present invention can be prepared from, for example, poly(alkylene glycol), which is known and commercially available and can be obtained from commercial sources.

[0099] The terminal carboxyl group can be synthesized by methods known in the art, such as those disclosed in US8067505B2 or by methods described by Fishman, A et al.

[29] and the references cited therein.

[0100] The inventors focused on constructing a Zn-air rechargeable battery with a heavy metal-free, carbon-based air cathode, employing an α,ω-dicarboxylic acid-poly(ethylene glycol) electrolyte additive. First, α,ω-dicarboxylic acid-PEG derivatives with different molecular weights were synthesized in the presence of a chromium oxide (VI) catalyst. Then, cylindrical and rectangular battery cells were fabricated to test the electrochemical performance of the system. Furthermore, cyclic voltammetry measurements were performed to understand the role of the dicarboxylic acid telechelic additive.

[0101] This invention relates to a novel rechargeable Zn-air alkaline battery developed using a carbon / graphite cathode and a zinc anode. The use of the carbon / graphite cathode enables a continuous oxygen supply and has proven to be a suitable electrode for rechargeable Zn-air alkaline batteries through long-term performance testing. To avoid the formation of dendritic and / or other types of deposits, dicarboxylated telechelic PEGs with different molecular weights (600 Da, 1500 Da, and 3300 Da) were synthesized and used as additives in the electrolyte. Possible mechanisms of action for these additives are proposed.

[0102] In a particular embodiment, the rechargeable Zn-air alkaline battery of the present invention includes a carbon-based air cathode comprising a graphite body or component (e.g., graphite rod 20) disposed within the battery body, and a Zn-anode (preferably a Zn-anode plate 11), wherein the anode space and the cathode space are separated by a separator (separator) made of a cellulose membrane, such as regenerated cellulose, for example, celluloid. In a preferred embodiment, the battery body has a rectangular arrangement. In a particular arrangement, the cathode 20 is fixed within the battery body, for example, within a frame, such as a plastic frame, like frame 50 (PE or polyethylene frame). A dicarboxylated telechelic poly(alkylene glycol) is present in the electrolyte, preferably placed in the same location as the anode (preferably Zn-anode plate 11), i.e., on the anode side of the separator. The electrodes comprise electrolyte ions permeable to the separator.

[0103] In one embodiment, the electrodes have a flat arrangement. In this arrangement, a graphite / carbon air cathode 20 exists within a flat frame 50 to provide mechanical strength, a separator 30 separating the cathode space from the anode space is cellulose, and the anode comprises a flat Zn-plate 11 surrounded by a reservoir 70.

[0104] In a preferred embodiment, the rechargeable Zn-air alkaline battery is a flexible Zn-air alkaline battery, which exhibits significantly improved mechanical flexibility under repeated bending and deformation compared to conventional Zn-air battery technology. In a preferred embodiment, the battery body of the flexible rechargeable Zn-air alkaline battery has a planar arrangement with bendable structural features, such as the battery body being placed within a frame, separated by separators, or interconnected within the planar arrangement. Preferably, the flexible rechargeable Zn-air alkaline battery can be used in wearable electronic applications.

[0105] During the operation of the battery body 60, in the event of an electrode reaction as described herein, wires are connected to the electrodes, and a potential difference is generated between the electrodes. This potential difference can be measured, for example, by the wires, and if a circuit is closed between the electrodes (preferably, for example, the wires 60 are connected), the potential difference can generate a current.

[0106] Theoretical aspects and workings of novel Zn-air rechargeable batteries

[0107] To avoid deposit formation, the rate of charge transfer should be reduced. This involves using methods that affect free Zn. 2+ Additives with varying ion concentrations can alter the reaction rate of the electrode process. Based on the generally accepted electrochemical processes in this system, we consider the following reaction occurring on the Zn electrode (Scheme 1):

[0108]

[0109]

[0110] Zn(OH)₂→ZnO+H₂O R₃

[0111] Option 1. The reaction occurs on the zinc electrode.

[0112] If Zn(OH)₂ is present in the electrolyte at the boundary of the Zn electrode, an irreversible dehydration reaction may occur, leading to the formation of a solid ZnO layer on the electrode surface. This ZnO layer reduces the active surface area, thus significantly decreasing the battery's capacity and coulombic efficiency, ultimately resulting in corrosion of the zinc electrode.

[0113] Carbon / graphite air electrode

[0114] A suitable amount of carbon is required to maintain a stable, steady-state state of the air electrode through oxygen adsorption / desorption (Scheme 2, R4). To achieve our fundamental goal, namely, to design a high-performance Zn-air rechargeable battery, we elaborate on and utilize the following methods:

[0115] To reduce the rate of charge transfer, we used strong complexing agents and / or strong chelating agents, namely PEG-(COOH)2 with different number-average molecular weights. Thus, Zn 2+ The concentration (activity) of ions can be reduced near the Zn electrode. It is important to note that, according to the present invention, the macromolecular chelating agent should be bifunctional in order to remove OH groups from the inner coordination layer of the mixed complex. - The presence of the macromolecular PEG-(COOH)2 in the mixed complex also increases the hydrodynamic volume of the complex, thus reducing ion mobility. This effect causes the mixed complex to remain essentially near the Zn electrode, [Zn(OH)4]. 2- Except for ions. This process can be visualized in scheme 2 as follows:

[0116]

[0117]

[0118]

[0119]

[0120] Option 2. Reactions at the cathode (R4) and anode (R5), in addition, the proposed complex formation process (R6, R7) occurs on the Zn electrode.

[0121] In a specific implementation scheme, according to scheme 2, in the presence of PEG-(COO) - In the case of )2, no Zn(OH)2 formation occurred, thus ruling out ZnO precipitation. The results of rechargeable battery tests verifying the inhibitory effect of dicarboxylated telechelic PEG on deposit formation are discussed below.

[0122] In this invention, dicarboxylated telechelic poly(alkylene glycol) is used as an additive in the electrolyte for reduction in a Zn electrode (preferably a Zn plate).

[0123] In the arrangement according to the invention, the battery has an initial battery potential of 1.2V to 1.6V, preferably 1.25V.

[0124] If the dicarboxylated telechelic poly(alkylene glycol) as defined in this article is added to the electrolyte, the battery will not produce H2 gas during normal operation.

[0125] Dendritic deposition was suppressed by using a high current density (7.5 mA / cm²) in the absence and presence of additives. -2 The battery was cycled through charge and discharge cycles to demonstrate this. Strong deposit formation was observed in the first cycle. Conversely, the addition of dicarboxylated telechelic PEG prevented dendritic and moss-like deposits. Cyclic voltammetry measurements revealed that both the anodic and cathode peaks shifted to higher and lower potentials, respectively, resulting in increased peak spacing.

[0126] The battery stability and charge / discharge cycles were tested in the presence of various additives. A wider potential range was observed without additives, while the synthesized dicarboxylated telechelicergic PEG additive stabilized the cycle performance for up to four hours. Furthermore, near-100% coulombic efficiency and constant capacity were achieved in each case. The 20th discharge step was also investigated with and without additives. A stretching exponential fit was shown to be suitable for describing the change in battery potential in the absence of additives. Conversely, the presence of the dicarboxylated telechelicergic PEG additive resulted in an Et... 电池 More complex decay over time. To describe these E... 电池 An equation consisting of rapid simple exponential decay and slow rigid exponential decay terms was proposed for the time curve. Dicarboxylated telechelicer PEG600 was tested for 68 hours, during which almost constant capacity and coulombic efficiency (100%) were obtained. The surface of the zinc electrode was characterized by SEM. SEM images showed moss-like deposits forming in the absence of additives. However, in the presence of dicarboxylated telechelicer PEG600, the surface of the zinc electrode remained smooth after long-term performance testing in the battery of this invention.

[0127] In an alternative implementation, a prototype of a stable Zn-air battery was fabricated. The synthesis of telechelic polyethylene glycol-polypropylene glycol-polyethylene glycol (POLOXAMER) was performed (Mn, starting material: 1800 g / mol, propylene glycol content 50% w / w). Dicarboxylic acid derivatives were prepared by oxidation with chromic acid using commercially available starting materials as dihydroxy-telechelic derivatives, following the aforementioned experimental method. The structure of the resulting oxidation product was identified by MALDI-TOF-MS.

[0128] Electrode reactions P6 and P7 can be described with necessary modifications.

[0129] Surprisingly, a stable battery potential with 100% coulombic efficiency was obtained throughout the measurement period. The internal resistance of the battery body decreased, thus allowing for charging / discharging over a narrow voltage range. This range is significantly smaller than that observed with carboxyl telechelic PEG polymers.

[0130] The present invention will be further illustrated below with reference to examples, in order to explain certain preferred embodiments.

[0131] Example

[0132] Materials and methods

[0133] Material

[0134] Zinc foil (100×100×0.25mm, 99.9%), poly(ethylene glycol) samples with different molecular weights (PEG600, PEG1500 and PEG3300, with Mn = 600Da, 1500Da and 3300Da), poloxamer (Mn, starting: 1800 g / mol, propylene glycol content 50% w / w), activated carbon (i.e., carbon (analytical grade)), chromium (VI) oxide (analytical grade), sulfuric acid (analytical grade), sodium chloride (analytical grade), and magnesium sulfate (analytical grade) were obtained from Merck (Darmstadt, Germany). The Zn electrode was cleaned by rinsing with n-hexane and dried before use. Spectroscopic grade graphite rods were used as the graphite rods (CeramicsPraha, Prague, Czech Republic). Dichloromethane (HPLC grade), n-hexane (HPLC grade), diethyl ether (reagent grade), zinc oxide (analytical grade), and potassium hydroxide (analytical grade) were from VWR (Debrecen, Hungary). Use all chemicals as is.

[0135] Potentiometer

[0136] Testing and cyclic voltammetry (CV) measurements of the homemade Zn-air rechargeable battery were performed using a BioLogic SP-150 potentiostat (Cesine-Parisé, France) equipped with the EC-Lab software package.

[0137] Scanning electron microscope

[0138] To visualize the morphology of the Zn electrode surface, a scanning electron microscope (SEM) – a Hitachi S-4300 scanning electron microscope (Tokyo, Japan) – was used.

[0139] Mass spectrometry

[0140] Matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS) measurements were performed using a Bruker Autoflex Speed ​​mass spectrometer. In all cases, an accelerating voltage of 19 kV was used in positive ion mode. Ions were detected in reflective mode, with 21 kV and 9.55 kV applied as reflective voltage 1 and voltage 2, respectively. A solid-phase laser (355 nm, ≥100 μJ / pulse) operating at 500 Hz was used to generate laser desorption, and a total of 2000 shots were performed. MALDI-TOF MS spectra were externally calibrated using poly(ethylene glycol) standards (Mn = 600 Da, 1500 Da, and 3300 Da).

[0141] The sample was dissolved at a concentration of 10 mg / mL in a mixture of water and methanol (80 / 20 V / V). Samples for MALDI-TOF MS were prepared using a 2,5-dihydroxybenzoic acid (DHB) matrix. The matrix at a concentration of 20 mg / mL was dissolved in the same water / methanol mixture as the sample. The matrix solution, sample solution, and potassium trifluoroacetate solution (5 mg / mL in water / methanol (80 / 20 V / V)) used as a cationizing agent were mixed at a ratio of 10:2:1 (V / V / V) (matrix / analyte / cationizing agent). A 0.5 μL volume of the solution was deposited onto a metal sample plate and allowed to air dry.

[0142] Synthesis and characterization of dicarboxylated telechelic PEG

[0143] The oxidation of PEG (PEG600, PEG1500 and PEG3300) was carried out according to reference

[29] . The following is a typical improved method for the synthesis of dicarboxylated telechelic PEG by means of an example for PEG1500 g / mol. A 100 mL round-bottom three-necked flask equipped with a magnetic stirrer, thermometer, dropping funnel and reflux condenser was used. A mixture of 25 mL water and 8 mL sulfuric acid was added to the reaction flask at room temperature, and 5 g of PEG (1500 g / mol, 3.33 mmol) was dissolved in it. After the PEG was completely dissolved, 2.62 g (26.2 mmol) of CrO3 dissolved in 5 mL water was added to the dropping funnel. The oxidant was introduced into the reactor for 20 minutes at a maximum temperature of 55 °C. The reaction mixture was stirred for an additional three hours. The color of the mixture changed from orange to blue-green, indicating that the reaction was complete. Then 25 mL water was added to the reaction mixture, transferred to a separatory funnel and extracted with 3 × 100 mL CH2Cl2. The organic layers were then combined and washed with water (2 × 25 mL) and saturated NaCl solution (2 × 25 mL) – (to increase the yield, washing with saturated NaCl solution only was used in the case of PEG600) – and the organic phase was dried overnight with MgSO4. The solvent was evaporated under vacuum at room temperature. The honey-like product was mixed with 150 mL of cold diethyl ether, and the precipitate was filtered and dried. Yield: 3.94 g (79%).

[0144] The formation of the target reaction product (i.e., PEG-(COOH)2-s) was confirmed by MALDI-TOF MS, see [link to MALDI-TOF MS]. Figure 1a The dicarboxylated telechelicerae shown is PEG1500. For two other types with M... n The spectra of dicarboxylated telechelic PEGs with values ​​of 3300 Da and 600 Da are shown in [the original text]. Figure 1b Neutralization in Figure 1C.

[0145] Synthesis and characterization of dicarboxylated telechelic poly(ethylene glycol)-poly(propylene glycol) copolymer poloxamer

[0146] The synthesis of dicarboxylated telechelic poly(ethylene glycol)-poly(propylene glycol) copolymer poloxamer was carried out by the same method as dicarboxylated telechelic PEG (by oxidizing the starting material).

[0147] Construction of Zn-air rechargeable batteries

[0148] A zinc-air rechargeable battery is constructed using carbon / graphite cathodes and zinc anodes with two different geometries. The cathode chamber 20 is made of a polyethylene (PE) skeleton, which is either cylindrical (4 cm in diameter) or rectangular prism (3 × 3 × 9.5 cm (length × width × height)). Cotton fingers or linings (cotton fabric) 40 are attached to the frame (PE skeleton) 50 to form a cotton fabric wall inside the cylinder or rectangular prism. Cellulose (i.e., separator 30), acting as a semi-permeable membrane, is then inserted into the cotton chamber. Finally, the internal space is filled with carbon (approximately 22 g), and a graphite rod 21 is placed in the center of the carbon-filled interior to form the cathode 20. The anode 10 has a zinc plate 11 (0.25 mm thick, 10 cm long, 11 mm wide) fixed to the PE skeleton, and its distance from the cotton wall is maintained at a constant value (approximately 2 mm). The prepared battery was inserted into a 200 mL storage tank 70 (beaker), which was then filled with a 6 M potassium hydroxide aqueous solution containing 0.25 M ZnO through a carbon bed. The liquid level in the storage tank 70 (beaker) was kept constant (the height of the alkaline solution was 8 cm). To test the effect of the dicarboxylated telechelic PEG additive, these PEG derivatives were used at a concentration of 2 × 10⁻⁶. -4 The concentration of M is dissolved and / or emulsified in KOH / ZnO solution.

[0149] Results and discussion

[0150] Preliminary experiments and battery construction

[0151] Besides the appropriate performance of the battery, the materials used also play a crucial role in the construction of Zn-air rechargeable batteries. The electrolyte of the battery contains only KOH and [Zn(OH)4]. 2- And non-toxic dicarboxylated telechelic PEG additives. The cathode consists of graphite and carbon. In this construction, polyethylene and cotton form the electrode framework, while celluloid is used as a semi-permeable membrane (i.e., a separator). All materials used to construct the Zn-air rechargeable battery are readily available, non-toxic, and meet the main criteria for green and sustainable chemistry. Figure 2 shows the arrangement and image of the novel Zn-air rechargeable battery.

[0152] To understand our simple Zn-carbon / graphite-air battery, we first created a Zn-galvanic cell. The characteristics of the cell were determined by continuously discharging it with a 5mA discharge current.

[0153] The discharge results of the cylindrical galvanic cell are shown in Figure 3. The initial cell potential was 1.25V. Discharge was forcibly terminated after 60 hours of operation. The near-constant potential indicates that the cell lifespan may be much longer. The long lifespan is due to continuous oxygen replenishment from the air. A capacity greater than 300mAh was achieved during discharge. Figure 3 shows that the application of a carbon / graphite cathode stabilizes the discharge process and that the operation of the Zn-air battery is sustainable. Interestingly, the discharge curves can be well described using the stretching exponential function shown in Figure 3.

[0154]

[0155] Where ΔE s This represents the change in electric potential. k s It is the rate coefficient of decay, μ is the exponential factor of stretching, and E ∞ It is the final electric potential. E ∞ ΔE s k s The fitting parameters for μ are 1.22V, 0.029V, and 0.058h, respectively. -1 And 0.606.

[0156] The possible reasons for the emergence of the stretched exponential function will be discussed later.

[0157] However, as discussed in the introduction, the application of Zn-air systems as rechargeable batteries has encountered difficulties due to the formation of Zn deposits and unstable operation. To gain a deeper understanding of the operation of our battery cell, alternating charge and discharge events were performed. Additionally, novel rectangular battery cells were fabricated to obtain a uniform geometry, and the performance of our battery cell with a novel dicarboxylated telechelic PEG additive was tested. Figure 4 The cycle of charge and discharge steps is shown in the absence of additives, while the second cycle was recorded in the presence of dicarboxylated telechelicerlic PEG1500 additive.

[0158] The charging current density under these conditions is 7.5 mA / cm². -2 During the first charging step, strong deposit formation was observed, such as... Figure 4 This was confirmed in [the study]. Due to the higher local current density, the deposits expanded more near the sides of the electrode. The structure of the deposits was mainly moss-like, but dendritic crystals also appeared. After the dense charging event, at 0.625 mA / cm², [the following occurred]. -2Discharge at a current density. This step removed most of the deposits from the Zn-electrode surface, confirming the presence of moss-like deposits and indicating that deposition and dissolution are irreversibly reversible. Before starting the next cycle, dicarboxylated telechelicer PEG1500 was added to the electrolyte. Using the same charging conditions as the first step, the electrode surface remained almost identical after charging. Importantly, no significant amount of new deposits was observed in the presence of the dicarboxylated telechelicer PEG additive; only some deposits formed during the first cycle showed an increase in size. Therefore, dicarboxylated telechelicer PEG exhibits high efficiency in suppressing deposit formation.

[0159] Cyclic voltammetry using a telescopic PEG

[0160] Cyclic voltammetry measurements were performed to study zinc deposition and dissolution. Figure 5a and 5b The presence and absence of dicarboxylic telechelicer PEG600 (M) were shown. n The volt-ampere diagram at 600 Da, and Figure 5b It is a dicarboxylated telechelic PEG1500 and Figure 5c For PEG3300 (M respectively) n =1500Da and 3300Da). The working electrode, counter electrode, and reference electrode are zinc wire, graphite, and zinc wire, respectively.

[0161] The voltage-current curve is between -0.5 and 0.55 V vs. Zn / Zn. 2+ Recorded within the range. A cathode peak was detected at a potential below -0.1V, while an anode peak was around 0.1V. The separation of the anode / cathode peaks was higher in the presence of additives than in the additive-free system. Shimizu et al.

[20] reported a similar change in the anode peak when an anionic additive was used in the electrolyte. The difference between the positions of the anode and cathode peaks indicated a higher overpotential, however, this difference was lower compared to other types of additives used by Truduckon et al.

[29] . The voltammograms measured in the presence of PEG-(COOH)2 additives (Figure 2) show clear reduction and oxidation peaks. The results of cyclic voltammetry determinations are shown in Table 1.

[0162] Table 1. Results of cyclic voltammetry include anode / cathode peak positions, current density, and peak separation.

[0163]

[0164]

[0165] The CV plots show the shifts in the positions of the anodic and cathodic peaks. Compared to the additive-free systems of dicarboxylated telechelic PEG with molecular weights of 600, 1500, and 3300 Da, the cathodic shifts were 25 mV, 24 mV, and 52 mV, while the anodic peak shifts were 50 mV, 7 mV, and 65 mV. The highest anodic / cathode peak separation was observed for dicarboxylated telechelic PEG3300, which is likely due to the incomplete dissolution of the polymer in concentrated KOH solution.

[0166] Rectangular rechargeable Zn-air battery with telescopic PEG

[0167] Use 2mAcm -2 The charge-discharge cycle performance of novel Zn-air rechargeable batteries with different additives was tested using current density measurements. The time limit for the steps was 5 minutes, and the potential limits were 1.0 and 1.8 V. The battery potential was approximately 1.27 V. It is clearly visible in Figure 6 that the additive-free system exhibits an increasing range of battery potential over time (efficiency and capacity curves are shown in the supporting information). The change in potential indicates the formation of irreversible deposits on the zinc electrode surface. Furthermore, different molecular weights of dicarboxylated telechelic PEGs have a favorable effect on the stability of the potential. In each case, the potential falls within the range of 1.2 V to 1.6 V, and the cycle performance shows only small differences. Dicarboxylated telechelic PEG600 gives the most stable charge-discharge curve (Figure 6), very small changes are observed in the case of dicarboxylated telechelic PEG1500, while distorted cycling is obtained in the presence of dicarboxylated telechelic PEG3300. The trend observed in the performance of dicarboxylated telechelic PEG additives is likely due to the fact that the chelating ability of the carboxylic acid groups at the ends of the PEG chain for Zn(II) ions decreases with increasing chain length. Furthermore, it can be hypothesized that the Zn-PEG(COO)2 complex can adsorb onto the surface of the Zn-electrode, thereby reducing the rate of charge transfer. The coulombic efficiency of the tested battery is close to 100%, indicating high reproducibility of charge / discharge cycles.

[0168] For each measurement, the battery potential change was studied at the 20th discharge cycle (with and without additives) to visualize the effect of the dicarboxylated telechelic PEG additive. Figure 7 ).

[0169] The curve obtained without the addition of additives can be approximated by stretching the exponential function (see Equation 1). Figure 7 a) This behavior may stem from the broad distribution of activation energies for the electrochemical reactions caused by the different surfaces of the Zn electrode. Conversely, the presence of PEG additives leads to E 电池 More complex decay over time ( Figure 7 b- Figure 7 d). We found that E 电池The curve over time can be adequately approximated by Equation 2.

[0170]

[0171] Where ΔE f and ΔE s These represent the potential changes corresponding to rapid and slow decay, respectively. k f and k s These are the rate coefficients for rapid and slow decay, respectively; μ is the stretching exponent factor; and E... ∞ It is the final electric potential.

[0172] Eq.2 consists of two exponential terms, the first of which represents E 电池 The rapid decay indicates a rapid rearrangement of the double-layer structure, thereby reducing the overpotential of the zinc electrode. The second term involves the stretching exponential function. Interestingly, the stretching exponential factor (μ) decreases as the chain length of the dicarboxylated telechelic PEG increases, while the corresponding k... s The value did not change significantly. To demonstrate the long-term stability of the novel Zn-air rechargeable battery, cycle performance measurements were extended to over 450 cycles (65 hours) in the presence of dicarboxylated telechelicer PEG600. Figure 8 The maximum potential during cycling increased slightly; however, stable cycling was observed. The stability of the Zn electrode was also confirmed by the capacity curves. The capacity was found to remain constant during the study, and a high coulombic efficiency (close to 100%) was achieved. The reversibility of the battery's charge / discharge was also confirmed by measuring the mass of the zinc electrode before and after long-term cycling performance measurements, and no significant change in electrode mass was observed.

[0173] The surface of the Zn electrode with telechelic PEG was characterized by scanning electron microscopy (SEM).

[0174] The effect of additives on deposit formation was investigated using SEM surface analysis of the Zn electrode. The electrode was washed with water and acetone after testing and then stored in cyclohexane prior to analysis.

[0175] Figure 9 Electrode images are shown after long-term cycling performance testing (68 hours) at different magnifications, with and without the dicarboxylated telechelicer PEG600 additive. The applied current density was 2 mA / cm². -2In the absence of dicarboxylated teleclaw PEG additives, a moss-like porous deposit formed on the electrode surface. The deposit covered a large area of ​​the electrode surface. Conversely, the application of dicarboxylated teleclaw PEG600 produced a highly improved morphology. The electrode surface was relatively smooth, and no needle-like dendrites or moss-like protrusions were identified. Energy dispersive spectroscopy (EDS) measurements confirmed that the elemental composition of the deposit was metallic zinc. A conventional EDS spectrum is shown below. Figure 10 middle.

[0176] SEM images of dicarboxylated telechelicerae PEG1500 and 3300 are shown in the supporting information (Fig. S9). In the presence of these additives, some protrusions formed during cyclic performance testing; however, their size remained very small.

[0177] A novel Zn-air rechargeable battery with telechelic polyethylene glycol-propylene glycol-polyethylene glycol (poloxam).

[0178] The experimental setup was identical to that described in the experiment with dicarboxylic telechelicer PEG600 (Figure 11). Except that the dicarboxylic telechelicer additive PEG600 was replaced by a dicarboxylic telechelicer poloxamer derivative, the composition of the electrolyte used was also the same as in the previous experiment. When mixed with 6M potassium hydroxide solution, the dicarboxylic acid poloxamer derivative did not completely dissolve, but instead formed an opaque emulsion.

[0179] Table 2 - Parameters for Battery Charge / Discharge Measurements

[0180]

[0181] Constant potential measurements confirmed a significant reduction in the duration of previously observed unstable (unstable) operation during battery cell operation, and a decrease in the charge / discharge range to 0.13V. Figure 12 The battery exhibited a stable potential throughout the measurement period with a coulombic efficiency of 100%. The internal resistance of the battery body was reduced, thus allowing for charging / discharging over a narrow voltage range. This range is significantly smaller (1.20–1.37 V) than the range observed with carboxylated telechelicerlic PEG polymers (1.12–1.60 V). The operation of the charge / discharge cycles also differed significantly from those with dicarboxylated telechelicerlic PEG (Mn: 600 Da, 1500 Da, 3300 Da).

[0182] Industrial applicability

[0183] Zn-air batteries are promising energy storage devices due to their high storage capacity and inexpensive structure. This paper reports the development of a novel Zn-air rechargeable battery featuring a carbon / graphite cathode and dicarboxylated telechelic polyethylene glycol (PEG) additives with different molecular weights (Mn: 600 Da, 1500 Da, 3300 Da). The battery is free of heavy metals, and all materials used are readily available and non-toxic. The battery operates at 7.5 mA and 2 mA / cm². -2 At charging current densities, synthesized dicarboxylated teleclaw PEG was successfully applied to suppress the formation of dendritic and moss-like deposits on the Zn electrode surface. The stability of the rechargeable battery was tested, with stable operation achieved using all synthesized dicarboxylated teleclaw PEG additives. Cyclic voltammetry measurements were also performed to understand the role of the dicarboxylated teleclaw additives. Furthermore, charge / discharge cycles up to 68 hours were conducted to investigate long-term cycling performance, during which a stable battery potential was obtained throughout the measurement period, with a coulombic efficiency approaching 100%. Mathematical modeling of the discharge step was also performed in the presence of the additives. The electrode surface after testing was analyzed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The additive-free system resulted in moss-like deposits, while the Zn electrode surface remained smooth in the presence of the dicarboxylated teleclaw PEG additives, and the electrode weight remained unchanged after long-term testing.

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Claims

1. A rechargeable Zn-air alkaline battery having a carbon-based air cathode and a zinc anode, the alkaline battery comprising a dicarboxylated telechelic polymer of C2-C3 alkylene glycol units (subunits or monomer units) as an additive in the electrolyte of the battery.

2. The rechargeable Zn-air alkaline battery according to claim 1, wherein, The dicarboxylated teleclaw polymer of the C2-C3 alkylene glycol unit is a dicarboxylated teleclaw polymer containing an ethylene oxide unit.

3. The rechargeable Zn-air alkaline battery according to claim 1 or 2, wherein, The anode comprises a Zn plate, and the cathode is composed of graphite and carbon.

4. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 3, wherein, The electrolyte of the battery contains only KOH and [Zn(OH)4]. 2- And non-toxic dicarboxylated telechelic PEG additives.

5. A rechargeable Zn-air alkaline battery according to any one of claims 1 to 4, wherein, Cellulose is used as a semi-permeable membrane, i.e., a separator.

6. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 5, wherein, The battery has an initial battery potential of 1.2V to 1.6V.

7. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 6, wherein, The dicarboxylated telechelic polymer used as an additive in the electrolyte of the battery is dicarboxylated telechelic PEG (α,ω dicarboxylated poly(ethylene glycol)).

8. The rechargeable Zn-air alkaline battery according to claim 7, wherein, The molecular weight of the dicarboxylated telechelic PEG is no higher than 3300 Da.

9. The rechargeable Zn-air alkaline battery according to claim 8, wherein, The molecular weight of the dicarboxylated telechelic PEG is not higher than 1500 Da.

10. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 7, wherein, The dicarboxylated telechelic polymer is poly(ethylene glycol-polypropylene glycol-poly(ethylene glycol)) (poloxam).

11. The rechargeable Zn-air alkaline battery according to claim 10, wherein, The molecular weight of the poloxamer is no higher than 5000 Da.

12. The rechargeable Zn-air alkaline battery according to claim 10 or 11, wherein, The poloxamer contains 30-70% w / w of propylene glycol.

13. The rechargeable Zn-air alkaline battery according to claim 12, wherein, The poloxamer contains 40-60% w / w of propylene glycol.

14. A rechargeable Zn-air alkaline battery according to any one of claims 1 to 13, wherein, The battery has a rectangular battery body.

15. The rechargeable Zn-air alkaline battery according to any one of claims 1 to 14, wherein, No H2 is generated during battery operation.

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