Composite organic electrode materials, organic electrochemical devices and their preparation methods

Abstract

This invention provides a composite electrode material comprising submicron particles of carbon oxide salts (e.g., having the formula M...). m (CO) n The composite electrode material comprises monocyclic carbon oxide alkali metal salts (where M = Li, Na, or K; 2 ≤ m ≤ 6; n = 4, 5, or 6) and functionalized carbon-based materials (e.g., graphene oxide). This composite electrode material is suitable for use in electrochemical devices operating at ultra-low temperatures.

Description

[0001] Priority document This application claims priority to Australian Provisional Patent Application No. 2023904029, filed on December 12, 2023, entitled “Composite Organic Electrode Materials, Organic Electrochemical Devices and Preparation Methods Thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure generally relates to electrochemical devices. In a particular form, this disclosure relates to an organic electrochemical device comprising a composite organic electrode material prepared from an oxocarbon salt. Background Technology

[0003] Manufacturing rechargeable batteries for high-latitude / high-altitude regions and deep-sea / defense / aerospace exploration presents unique challenges due to the need for operation in extreme environmental conditions. These applications require reliable energy storage systems capable of operating efficiently in ultra-low temperatures (e.g., ≤-40°C). Conventional batteries often struggle to maintain their performance under such extreme conditions.

[0004] Organic batteries have emerged as a promising alternative to traditional batteries in ultra-low temperature applications. Organic batteries offer several distinct advantages, such as the natural abundance and low cost of electrode materials, and especially the rapid kinetics associated with their flexible molecular structure and surface-controlled reactions, which circumvent the solid-state diffusion limitations of inorganic substrates. 1-7 Organic electrode materials (OEMs) have been applied to a variety of energy storage devices due to their versatility. Examples of such devices include non-aqueous Li-ion, Na-ion, K-ion, dual-ion batteries, multivalent metal batteries, aqueous batteries, all-solid-state batteries, and redox flow batteries. OEMs can exhibit superior performance in rechargeable batteries under extreme conditions, such as wide temperature ranges (-70°C to 150°C), wide pH ranges, and the presence of O2. Various types of organic biomass have been used to prepare electrode materials for energy storage devices. For example, supercapacitors have been made using cotton, bacterial cellulose (cellulose nanofibers), filaments, lignin, starch, sucrose, chitosan, bamboo, linden wood, gelatin, peanut shells, chitin, and sisal leaves.

[0005] However, OEMs may encounter problems such as low electronic conductivity, low redox stability, and rapid capacity decay. The battery performance of OEMs is determined by redox-active functional groups. Generally, the reduction of unsaturated bonds in organic molecules (such as C=C, C=N, C=O) forms free radical intermediates, generating negative charges on N or O atoms and unpaired electrons on C atoms. 8-9These organic intermediates are unstable and can dissolve in electrolytes, which ultimately leads to capacity loss and thus unsatisfactory cycling stability. 10-11 Over the past few decades, various strategies have been proposed to prevent the dissolution and formation of metastable active organic materials. 12 For example, designing functional membranes, polymerizing redox-active compounds, and custom electrolytes. 13-14 This enhances the stability of the organic electrode.

[0006] There is a need for new or improved organic electrode materials that can mitigate or overcome one or more technical problems and can be used under cryogenic conditions. Alternatively or additionally, there is a need for a known organic electrode material that can mitigate or overcome one or more technical problems and can be used under cryogenic conditions. Summary of the Invention

[0007] According to a first aspect, a composite electrode material is provided, comprising submicron particles of carbon oxide salt and functionalized carbon-based material.

[0008] In some embodiments of the first aspect, functionalized carbon-based materials are loaded onto particles of carbon oxide salts.

[0009] In some embodiments of the first aspect, the carbon oxide salt particles are crystalline particles.

[0010] In some embodiments of the first aspect, the functionalized carbon-based material includes or is graphene oxide.

[0011] In some embodiments of the first aspect, the composite electrode material is a composite organic electrode material comprising submicron particles of carbon oxide salt and graphene oxide, wherein the carbon oxide salt is derived from a natural source.

[0012] In some embodiments of the first aspect, the carbon oxide salt comprises or is a monocyclic carbon oxide salt. In some further embodiments, the carbon oxide salt comprises or is a monocyclic carbon oxide metal salt. In some further embodiments, the carbon oxide salt comprises or is a monocyclic carbon oxide alkali metal salt, such as sodium, lithium, and / or potassium salts. In a further embodiment, the carbon oxide salt comprises a salt having the formula M m (CO) n Monocyclic carbon oxide alkali metal salts or those with formula M m (CO) n A monocyclic carbon oxide alkali metal salt (where M = Li, Na, or K; 2 ≤ m ≤ 6; n = 4, 5, or 6). In a further embodiment, the carbon oxide salt comprises a salt having the formula M2(CO). nThe monocyclic carbon oxide alkali metal salt or has the formula M2(CO) n A monocyclic carbon oxide alkali metal salt (where M = Li, Na, or K; n = 4, 5, or 6). In a further embodiment, the carbon oxide salt comprises a monocyclic carbon oxide salt having the formula M m (CO)6 monocyclic carbon oxide alkali metal salt or having the formula M m (CO)6 is a monocyclic carbon oxide alkali metal salt (where M = Li, Na, or K; 2 ≤ m ≤ 4, for example, m is 2, 2.5, 3, 3.5, or 4). In a preferred embodiment, the carbon oxide salt comprises or is disodium macranthoate (i.e., Na2C6O6).

[0013] In some embodiments of the first aspect, the longest dimension of the submicron particles is from about 5 nm to about 800 nm, for example, from about 100 nm to about 800 nm. In some other embodiments, the longest dimension of the submicron particles is from about 200 nm to about 600 nm. In a further embodiment, the longest dimension of the submicron particles is from about 400 nm to about 500 nm.

[0014] In some embodiments of the first aspect, the crystalline submicron particles of the carbon oxide salt include or have rod-like, spherical, diamond-like, and / or irregular morphologies. In some other embodiments, the crystalline submicron particles of the carbon oxide salt include a diamond-like morphology. In a further embodiment, the crystalline submicron particles of the carbon oxide salt have a diamond-like morphology.

[0015] In some embodiments of the first aspect, the functionalized carbon-based material is graphene oxide, which comprises or is a monolayer of graphene oxide. In some other embodiments, the thickness of the monolayer of graphene oxide is from about 0.7 nm to about 1.2 nm.

[0016] In some embodiments of the first aspect, the water solubility of graphene oxide at room temperature is ≥ about 5 mg / ml. In some other embodiments, the water solubility of graphene oxide at room temperature is ≥ about 8 mg / ml. In some other embodiments, the water solubility of graphene oxide at room temperature is ≥ about 10 mg / ml.

[0017] In some embodiments of the first aspect, the carbon oxide salt and the functionalized carbon-based material are present in a weight ratio of about 12:1 to about 2:1. In some other embodiments, the carbon oxide salt and the functionalized carbon-based material are present in a weight ratio of about 10:1 to about 3:1 (e.g., about 8:1 to about 4:1). In a further embodiment, the carbon oxide salt and the functionalized carbon-based material are present in a weight ratio of about 5:1. In a further embodiment, when the composite electrode material consists of submicron particles of a monocyclic carbon oxide alkali metal salt (e.g., Na2C6O6) and graphene oxide, the weight ratio of the carbon oxide salt to the graphene oxide is about 5:1.

[0018] In some embodiments of the first aspect, the composite electrode material further includes a functional material, such as an aerogel. In some other embodiments, the functional material is selected from sodium alginate, chitosan, and agarose.

[0019] In some embodiments of the first aspect, the composite electrode material exhibits a reduced contact angle and increased interfacial wettability compared to individual carbon oxide salts.

[0020] In some embodiments of the first aspect, the electrode prepared from the composite electrode material exhibits approximately 110 mAh·g in a half-cell configuration at -50°C. -1 Approximately 125 mAh·g -1 (For example, 119 mAh·g) -1 ) capacity.

[0021] In some embodiments of the first aspect, the composite electrode material is used in electrochemical devices under ultra-low temperature conditions. In some further embodiments, the composite electrode material is used in electrochemical devices with temperatures ≤ about -30°C. In some further embodiments, the composite electrode material is used in electrochemical devices with temperatures ≤ about -40°C. In a further embodiment, the composite electrode material is used in electrochemical devices with temperatures ≤ about -50°C. In a further still embodiment, the composite electrode material is used in electrochemical devices with temperatures ≤ about -70°C.

[0022] According to a second aspect, a method for preparing a composite electrode material is provided, the method comprising: (i) Forming a first composition comprising a carbon oxide salt, water, and optionally an antisolvent; (ii) Forming a second composition comprising a functionalized carbon-based material, water, and an optional antisolvent; (iii) Mixing the first composition and the second composition to obtain the third composition; and (iv) Under conditions that allow the formation of a precipitate containing submicron particles of the carbon oxide salt and the functionalized carbon-based material, a certain amount of antisolvent is introduced into the third composition.

[0023] In some embodiments of the second aspect, the method for preparing the composite electrode material includes: (i) Introducing a carbon oxide salt into a first mixture containing water and an antisolvent to obtain a first composition; (ii) Introducing a functionalized carbon-based material into a second mixture containing water and an antisolvent to obtain a second composition; (iii) Mixing the first composition and the second composition to obtain the third composition; and (iv) Introduce a certain amount of antisolvent into the third composition under conditions that allow the formation of precipitates containing submicron particles of carbon oxide salts and functionalized carbon-based materials.

[0024] In some embodiments of the second aspect, the composite electrode material is the composite electrode material according to the first aspect. In some other embodiments, the method further includes (v) if the precipitate obtained from (iv) requires a crystalline state and the latter has not reached a crystalline state, then placing the precipitate under conditions that allow the carbon oxide salt to crystallize or conditions that improve the crystallization of the carbon oxide salt.

[0025] In some embodiments of the second aspect, the antisolvent used in steps (i), (ii), and (iv) is the same. In some embodiments, each of the antisolvents used in steps (i), (ii), and (iv) is selected from alcohols, ethers, ketones, and combinations thereof. In some further embodiments, the alcohol is selected from methanol, ethanol, n-propanol, isopropanol, isobutanol, and combinations thereof. In some further embodiments, the alcohol used in steps (i), (ii), and (iv) is the same. In a further embodiment, each of the alcohols used in steps (i), (ii), and (iv) is ethanol.

[0026] In some embodiments of the second aspect, the volume ratio of water to antisolvent contained in each of the first and second compositions, or in each of the first and second mixtures, is ≥ about 1:1. In some further embodiments, the volume ratio of water to antisolvent contained in each of the first and second compositions, or in each of the first and second mixtures, is ≥ about 1.5:1. In a further embodiment, the volume ratio of water to antisolvent contained in each of the first and second compositions, or in each of the first and second mixtures, is ≥ about 2:1. In a further embodiment, the first mixture is the same as the second mixture.

[0027] In some embodiments of the second aspect, each of the first mixture and the second mixture consists of water and ethanol. In some other embodiments, each of the first mixture and the second mixture consists of water and ethanol in a volume ratio of about 2:1.

[0028] In some embodiments of the second aspect, the volume ratio of the amount of antisolvent added to the third composition to the total amount of water in the first and second compositions is from about 6:1 to about 9:1. In some other embodiments, the volume ratio of the amount of antisolvent added to the third composition to the total amount of water in the first and second compositions is from about 7.5:1.

[0029] In some embodiments of the second aspect, the carbon oxide salt and the functionalized carbon-based material are used in a weight ratio of about 12:1 to about 2:1. In some other embodiments, the carbon oxide salt and the functionalized carbon-based material are used in a weight ratio of about 10:1 to about 3:1 (e.g., about 8:1 to about 4:1). In a further embodiment, the carbon oxide salt and the functionalized carbon-based material are used in a weight ratio of about 5:1. In a further embodiment, when the composite electrode material consists of submicron particles of a monocyclic carbon oxide alkali metal salt (e.g., Na2C6O6) and graphene oxide, the monocyclic carbon oxide alkali metal salt and graphene oxide are used in a weight ratio of about 5:1.

[0030] In some embodiments of the second aspect, step (iv) of introducing a certain amount of antisolvent into the third composition, under conditions allowing the formation of a precipitate comprising submicron particles of carbon oxide salts and functionalized carbon-based materials, is carried out at a temperature between about 0°C and about 70°C (at about 20°C or about 30°C). In some other embodiments, in step (iv), the antisolvent is added to the third composition. In a further embodiment, in step (iv), the antisolvent is added to the third composition in one step. In a further embodiment, step (iv) is carried out under stirring or agitation, for example, under ultrasonic treatment.

[0031] According to a third aspect, an electrochemical device is provided, comprising a composite electrode material according to the first aspect or a composite electrode material obtained according to the method described in the second aspect.

[0032] According to the fourth aspect, the use of the composite electrode material according to the first aspect or the composite electrode material obtained according to the method of the second aspect in the preparation of electrochemical devices is provided.

[0033] According to the fifth aspect, the use of the composite electrode material according to the first aspect or the composite electrode material obtained according to the method of the second aspect in an electrochemical device is provided.

[0034] In some embodiments of the third, fourth, or fifth aspects, the electrochemical device can operate at a temperature ≤ about -30°C. In some other embodiments, the electrochemical device can operate at a temperature ≤ about -40°C. In some other embodiments, the electrochemical device can operate at a temperature ≤ about -50°C. In a further embodiment, the electrochemical device can operate at a temperature ≤ about -60°C. In an even further embodiment, the electrochemical device can operate at a temperature ≤ about -70°C.

[0035] In some embodiments of the third, fourth, or fifth aspects, the electrochemical device is selected from batteries, cells, photovoltaic devices, and capacitors. In some other embodiments, the electrochemical device is a secondary battery. In a further embodiment, the electrochemical device is an ion-rechargeable secondary battery.

[0036] In some embodiments of the third, fourth, or fifth aspects, the electrochemical device comprises a composite electrode material as the negative electrode material. In some other embodiments, the electrochemical device comprises a MnFe-Prussian blue analogue (PBA) as the positive electrode material. In some other embodiments, the MnFe-Prussian blue analogue (PBA) is Na2MnFe(CN)6. In a further embodiment, the negative electrode material is a composite electrode material composed of crystalline submicron particles of Na2C6O6 and graphene oxide. In a further embodiment, the electrochemical device comprises NaPF6 as the electrolyte in diethylene glycol dimethyl ether (DGM).

[0037] In some embodiments of the third, fourth, or fifth aspects, the composite electrode material comprises a composite electrode material used as a positive electrode material. In some other embodiments, the composite electrode material comprises reduced sodium terephthalate (Na4TP) used as a negative electrode material. In some other embodiments, the positive electrode material is a composite electrode material composed of crystalline submicron particles of Na2C6O6 and graphene oxide. In a further embodiment, the electrochemical device comprises NaPF6 in diethylene glycol dimethyl ether as an electrolyte.

[0038] In some embodiments of the third, fourth, or fifth aspects, the electrochemical device achieves cycling stability of over 7000 cycles at approximately -40°C. In some other embodiments, the electrochemical device achieves cycling stability at 300 mA·g -1 High current density and maintain approximately 95 mAh·g at approximately -40°C for 7000 cycles. -1Up to 110 mAh·g -1 (For example, 101mAh·g) -1 ) discharge capacity.

[0039] In some embodiments of the third, fourth, or fifth aspect, the electrochemical device operates at 100 mA·g -1 The current density and performance at approximately -30°C over 300 cycles are approximately 130 mAh·g. -1 Approximately 140 mAh·g -1 (For example, 136 mAh·g) -1 ) capacity.

[0040] In some embodiments of the third, fourth, or fifth aspect, the electrochemical device is a pouch full-cell, and the pouch full-cell continuously powers four light-emitting diodes (LEDs, 2.0V) for more than 1.5 hours at -50°C. Attached Figure Description

[0041] Schemes of this disclosure will be discussed with reference to the accompanying drawings, in which: Figure 1 shows the solid-liquid-solid conversion reaction in disodium rhodizonate (DSR): (a) in-situ Raman spectra of submicron disodium rhodizonate (sub-DSR) and corresponding discharge-charge curves; (b) in-situ Raman 3D projection contour plot of Na|| sub-DSR / graphene oxide (GO) battery; (c) Raman spectra of sub-DSR / GO electrode under different discharge and charge states and corresponding discharge-charge curves. Figure 2 shows the improved battery performance through GO doping: (a) Na||DSR at 500 mA·g -1 (a) Current-voltage curves of the fifth cycle; (b) Molecular structures of DSR (Na2C6O6) and Na4C6O6, accompanied by photographs of diethylene glycol dimethyl ether (DGM) solutions infused with purchased DSR and synthetic Na4C6O6; (c) Na||DSR at 300 mA·g -1 (d) Cycling performance at 30°C; (e) SEM image of sub-DSR; (f) SEM image of sub-DSR / GO composite; (g) Na|| sub-DSR / GO at 300 mA·g -1 And cycling performance at 30°C.

[0042] Figure 3 shows the kinetics of the battery: (a) cyclic voltammetry (CV) curves of the sub-DSR; (b) CV curves of the sub-DSR / GO electrode at different temperatures; (c) Arrhenius plots of the C2 peak positive electrode current of the sub-DSR and sub-DSR / GO.

[0043] Figure 4 shows the molecular structure analysis: (a) in-situ Fourier-transform infrared spectroscopy (FTIR) contour plot of the sub-DSR electrode used for sodium ion storage; (b) in-situ FTIR contour plot of the sub-DSR / GO electrode used for sodium ion storage; (c) FTIR spectra of the prepared (I) sub-DSR powder and (II) sub-DSR / GO powder, and selected in-situ spectra corresponding to the original, fully discharged (1.0V) state and charged (3.2V) state for the first two cycles; synchrotron X-ray absorption spectra of the (d) OK edge and (e) CK edge of the sub-DSR powder and sub-DSR / GO powder; Figure 5 shows the ultra-low temperature sodium storage characteristics: electrochemical characteristics of the Na|| sub-DSR / GO half-cell: (a) at 50 mA·g -1 (a) Current density and cycling performance at -50°C and (b) corresponding discharge-charge curves for different cycles; Sodium storage performance of sub-DSR / GO||PBA full cells: (c) at -40°C and 100 mA·g -1 and 300 mA·g -1 Long-term cycling performance at current density (illustrated); (d) ultra-low temperature at -50°C and 50 mA·g -1 (e) Cycling performance at current density, suddenly cooled to room temperature, and then dropped to -40°C due to power failure of the hot chamber; and (f) corresponding discharge-charge curves for different cycles at -50°C; and (c) comparison of the cycling performance of this work with previously reported lithium-ion and sodium-ion batteries at ultra-low temperatures. (Note: Batteries without temperature markings were measured at -40°C).

[0044] Figure 6 shows the performance of the pouch cell at -50°C: (a) digital image of a single sub-DSR / GO||PBA pouch cell; (b) discharge-charge curves of a single sub-DSR / GO||PBA pouch cell for different cycles; (c) sub-DSR / GO||PBA pouch cell at 20 mA·g -1 (d) Current density and long-term cycling performance at -50°C (mass load of a single pouch cell is approximately 18.5 mg); Two pouch cells arranged in series power four green LEDs; Figure 7Raman spectra of (I) DSR powder and (II) sub-DSR / GO electrode are shown.

[0045] Figure 8 The X-ray diffraction (XRD) patterns of the purchased DSR and the synthesized Na4C6O6 powder are shown.

[0046] Figure 9 shows SEM images of sub-DSRs with different sizes and diamond-like morphologies synthesized using different precursor solution volumes (a) 90 ml and (b) 60 ml and H2O / EtOH at a volume ratio of 2:1.

[0047] Figure 10 shows optical images of the separators obtained from (a) sub-DSR and (b) sub-DSR / GO half-cells configured with 1M NaPF6-DGM electrolyte after three cycles at 1.0V full discharge.

[0048] Figure 11 The results show sub-DSR and sub-DSR / GO at 1000 mA·g -1 Current density and cycling performance at 30°C.

[0049] Figure 12 shows (a) sub-DSR and (b) sub-DSR / GO at 30°C and 1000 mA·g. -1 The first discharge-charge curve is shown below.

[0050] Figure 13 The rate capability of sub-DSR / GO at 30°C is shown.

[0051] Figure 14 shows the in-situ electrochemical impedance spectroscopy (EIS) spectra of the first cycle (a) and the second cycle (b) of Na|| sub-DSR. (100 mA·g) -1 The discharge-charge range at room temperature (RT) is 1.0 V to 3.2 V.

[0052] Figure 15 shows the in-situ EIS plots for the first cycle (a) and the second cycle (b) of Na||sub-DS / GO. (At 100 mA·g) -1 The discharge-charge range at RT is 1.0V to 3.2V.

[0053] Figure 16 shows the contact angle measurements on (a) sub-DSR and (b) sub-DSR / GO electrodes.

[0054] Figure 17 shows the EIS of a) sub-DSR and b) sub-DSR / GO at different temperatures.

[0055] Figure 18The FTIR spectra of (I) sub-DSR powder and (II) sub-DSR / GO powder are shown.

[0056] Figure 19 Synchronous X-ray absorption spectra of the Na K edge of sub-DSR powder and sub-DSR / GO powder are shown.

[0057] Figure 20 The synchronous X-ray absorption spectrum of the CK edge of graphene oxide is shown.

[0058] Figure 21 The results show sub-DSR and sub-DSR / GO half-cells at 200 mA·g -1 Current density and cycling performance at -30°C.

[0059] Figure 22 This demonstrates Na||sub-DSR / GO at a current density of 100 mA·g -1 Discharge-charge curves at -30°C.

[0060] Figure 23 The rate performance of Na||sub-DSR / GO at -30°C is shown.

[0061] Figure 24 The CV curves of Na||sub-DSR / GO at different scan rates and -30℃ are shown.

[0062] Figure 25 The results showed performance at -40°C and 300 mA·g -1 The continuous cycle measurement was performed on the sub-DSR / GO||PBA after 4200 cycles of testing at a current density. The testing was interrupted due to laboratory relocation and the battery was retested two weeks later.

[0063] Figure 26 The current density range at -40°C is shown to be 50 mA·g. -1 to 1000 mA·g -1 The multiplier capability.

[0064] Figure 27 shows (a) the sub-DSR / GO||PBA at 100 mA·g -1 (a) Temperature-dependent rate performance at current density; (b) EIS at different temperatures.

[0065] Figure 28 shows (a) the Na4TP|| sub-DSR / GO all-organic cell at 100 mA·g -1 (a) Current density and cycling performance at -30°C, with specific capacity based on sub-DSR / GO mass; (b) Corresponding discharge-charge curves for different cycles; Figure 29 shows (a) two sub-DSR / GO-PBA pouch cells in series and (b) digital images of the test in a hot chamber at -50°C. Detailed Implementation

[0066] As used in this article, the term "electrochemical device" refers to a device capable of converting chemical energy into electrical energy through electrochemical reactions, such as batteries, storage batteries, capacitors, and photovoltaic devices. Batteries can be secondary batteries, such as ion-ion batteries. A secondary battery is a battery that can be charged, discharged to a load, and recharged multiple times, as opposed to a primary battery or galvanic cell, which is supplied fully charged and discarded after use. Ion-ion batteries are rechargeable batteries in which ions (especially metal ions) move from the negative electrode to the positive electrode and then back during charging and discharging.

[0067] As used in this article, the term "electrode material" refers to the active material used as the positive or negative electrode in an electrochemical device. The term "positive electrode material" refers to the active material used as the positive electrode in an electrochemical device. The term "negative electrode material" refers to the active material used as the negative electrode in an electrochemical device.

[0068] As used in this article, the term "organic electrode material" refers to electrode materials that can be derived from biomass. Many organic electrode materials can be synthesized from biomass using green chemistry techniques with negligible environmental impact. For example, the organic electrode lithium rosinate (Li₂C₆O₆) can be prepared from natural glycosinositol, which exists in corn plants in the form of hexaphosphate.

[0069] As used herein, the term "carbon oxide salt" refers to a salt compound in which all or almost all carbon atoms have a carbonyl oxygen functional group or its hydrate. Examples of carbon oxide salts are monocyclic carbon oxide salts. Further explanation follows.

[0070] The term “ultra-low temperature” as used in this article refers to a temperature ≤ about -30°C, such as ≤ about -40°C, ≤ about -50°C, ≤ about -60°C, or ≤ about -70°C.

[0071] The term “submicron” as used in this article refers to dimensions smaller than 1,000 nanometers, such as 5 nanometers to less than 1,000 nanometers or 10 nanometers to 800 nanometers.

[0072] The term "functionalized carbon-based material" as used in this article refers to carbon-based materials with functional groups. Functional groups can be selected to increase the hydrophilicity of carbon materials, which in turn makes them more suitable for use in aqueous environments. For example, the functional group can contain oxygen. Oxygen functional groups include, but are not limited to, hydroxyl, ketone, lactone, carboxyl, quinone, and / or epoxy groups.

[0073] This disclosure stems from the inventors' discovery that graphene oxide in composite electrode materials (e.g., composite organic monocyclic carbon oxide salts) effectively anchors unstable intermediate organic substances, enabling rapid conversion reaction kinetics on the electrode during cycling and exhibiting ultra-long-term stability. For composite electrodes, the π-conjugated interactions of graphene oxide effectively delocalize the energy density of unpaired electrons on the C atoms of the electrode material (e.g., Na₂C₆O₆), thereby significantly reducing side reactions on C atoms with a clear C=C band. The intermediate interacts with the π-electron cloud of graphene oxide, forming charge-transfer complexes through π-π interactions, thus enabling rapid conversion reaction kinetics on the C=O atoms during carbonyl redox reactions (C=O₂O₆ ... CO - The study modulates redox reactivity and suppresses side reactions in the electrode. Smaller particle sizes with increased contact area were found to accelerate charge transfer and shorten diffusion paths for metal ions (e.g., alkali metal ions), which in turn improves the electrochemical performance of the composite electrode materials. Composite electrode materials incorporating graphene oxide exhibit reduced contact angles and increased interfacial wettability. The π-π interactions between carbon oxide salts (e.g., monocyclic carbon oxide salts) and graphene oxide, along with increased interfacial wettability, significantly enhance the overall kinetics and favorably influence the electrode activation energy, leading to stable resistance and more efficient carbonyl redox reactions at ultra-low temperatures.

[0074] Therefore, the present invention provides a composite electrode material comprising submicron particles of carbon oxide salts and functional carbon-based materials.

[0075] Organic electrode materials are widely used in rechargeable batteries due to their low cost, abundance, environmental friendliness, and high sustainability. Therefore, in certain forms, composite electrode materials can be composite organic electrode materials based on carbon oxide salts and graphene oxide, where the carbon oxide salts are derived from natural sources. It is well known that carbonyl groups act as redox active sites in carbon oxide salts.

[0076] Among carbon oxide salts, monocyclic carbon oxide salts, especially monocyclic carbon oxide metal salts, can be considered. Monocyclic carbon oxide metal salts include, but are not limited to, alkali metal salts, such as sodium, lithium, and / or potassium salts. Crystalline monocyclic carbon oxide alkali metal salts can possess ideal layered structures and conjugated properties for the insertion / extraction of alkali metal ions. If desired, mixtures of monocyclic carbon oxide metal salts can be used, such as a mixture of Na₂C₅O₅ and Na₂C₆O₆.

[0077] For illustrative purposes, monocyclic carbon oxide alkali metal salts can have the formula M m (CO) n(M = Li, Na, or K; 2 ≤ m ≤ 6; n = 4, 5, or 6). "m" can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6. In the embodiments, the monocyclic carbon oxide alkali metal salt has the formula M. m (CO)6 (M = Li, Na, or K; 2 ≤ m ≤ 4, e.g., m is 2, 2.5, 3, 3.5, or 4). In another embodiment, the monocyclic carbon oxide alkali metal salt has the formula M2(CO). n (M = Li, Na, or K; n = 4, 5, or 6). When n = 4, it can be called a squaric acid salt or a squaric acid salt. When n = 5, it can be called a ketoacid salt or a ketoic acid salt. When n = 6, it can be called a macaric acid salt or a macaric acid salt. Their molecular structures are shown below:

[0078] It is now known that ketone acid and malic acid are both products of the microbial oxidation of inositol (hexahydroxycyclohexane), a compound widely distributed in plants. M2(CO)5 / M2(CO)6 salts can reversibly insert two or four metal ions, while M2(CO)4 may exhibit lower electrochemical activity. Taking Na2(CO)5 and Na2(CO)6 as examples, the sodium insertion / deinsertion mechanism is shown below.

[0079]

[0080]

[0081] Disodium rosinate (Na₂C₆O₆) has proven to provide good charging capacity. Considering that disodium rosinate has a capacity of 501 mAh·g... -1 With its high theoretical specific capacity and crustal abundance, it is a preferred candidate for sodium-ion batteries (SIBs). Lithium rosinate (Li₂C₆O₆) has reportedly exhibited a specific capacity of 590 mAh·g⁻¹, based on the four-electron redox chemistry of lithium-ion batteries. -1 The theoretical capacity.

[0082] The aforementioned monocyclic carbon oxide alkali metal salts can be prepared by a one-pot proton exchange reaction with different metal ions (M=Li, Na, K) and frameworks (n=4, 5, 6), and can be used in rechargeable lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries. These monocyclic carbon oxide alkali metal salts are also commercially available, for example, from Sigma-Aldrich.

[0083] Functionalized carbon-based materials can be any suitable material. It is proposed that functionalized carbon-based materials possess functional groups (e.g., oxygen functional groups including but not limited to: hydroxyl, ketone, lactone, carboxyl, quinone, and / or epoxy groups) and π-electron clouds to anchor unstable intermediate organic substances. In some cases, functionalized carbon-based materials are soluble in water. A suitable material is graphene oxide (GO). GO has various oxygen functional groups attached to the graphene lattice at random positions. Examples of oxygen functional groups include epoxides (COC), carbonyl groups (C=O), hydroxyl groups (C-OH), and carboxyl groups (OH-C=O). The functional groups present on GO are polar, giving it high hydrophilicity and water solubility. Without being bound by theory, the inventors propose that graphene oxide in composite electrode materials (e.g., composite organic monocyclic carbon oxide salts) can effectively anchor unstable intermediate organic substances (e.g., Na4C6O6) and enables rapid conversion reaction kinetics on the electrode during cycling with ultralong-term stability. The π-conjugation interaction of graphene oxide can also effectively delocalize the energy density of unpaired electrons on the C atoms of electrode materials (such as Na2C6O6), thereby significantly reducing side reactions on the C atoms of the composite electrode.

[0084] The graphene oxide used herein may be in powder form, which is advantageous for better solubility. A dispersion of graphene oxide in water / ethylene glycol / dimethylformamide (DMF) or a dispersion of graphene oxide in water can be used. Graphene oxide is commercially available, for example, from Hangzhou Gaoxi Technology Co., Ltd., China. Graphene oxide can also be prepared from pure graphite powder by methods known in the art, such as the Hummer process or a modified Hummer process. For the purposes of this disclosure, monolayer graphene oxide is preferred. The monolayer thickness of the monolayer graphene oxide can be from about 0.70 nm to about 1.20 nm, for example, about 0.75 nm, about 0.8 nm, about 0.85 nm, about 0.9 nm, about 0.95 nm, about 1.0 nm, about 1.05 nm, about 1.10 nm, about 1.15 nm, and about 1.20 nm. Advantageously, the graphene oxide used in this paper has a water solubility of ≥ about 5 mg / ml, ≥ about 8 mg / ml, or even ≥ about 10 mg / ml at room temperature.

[0085] When used in the composite electrode materials disclosed herein, it may be desirable for the carbon oxide salts to be in a crystalline state. The morphology of the carbon oxide salt crystals within the composite electrode material is not limited. The carbon oxide salt crystals within the composite electrode material may include rod-like, diamond-like, spherical, and / or irregular morphologies, or have rod-like, diamond-like, spherical, and / or irregular morphologies. In embodiments, the crystalline submicron particles of the carbon oxide salt include or have a diamond-like morphology.

[0086] Preferably, the submicron particles of the carbon oxide salt substantially comprise or consist of crystalline submicron particles. The inventors propose that the smaller particle size, with its increased contact area, accelerates charge transfer and shortens the diffusion path of metal ions (e.g., alkali metal ions), which in turn contributes to improved electrochemical performance of the composite electrode material. The size of the carbon oxide salt can be controlled by adjusting precipitation conditions, such as adjusting the concentration of the raw material and the volume ratio of water to antisolvent (e.g., alcohol solvent) used in precipitation. The longest dimension of the submicron particles can be from about 5 nm to less than about 1000 nm, for example, from about 5 nm to about 800 nm. In some cases, the longest dimension of the crystalline submicron particles is from about 200 nm to about 600 nm, or from about 400 nm to about 500 nm, for example, about 400 nm, 450 nm, or 500 nm.

[0087] In the case of diamond-like morphology Na₂C₆O₆, it can be synthesized using molecular self-assembly techniques and solvent exchange processes. When using a mixture of alcohol and water (e.g., water and ethanol), Na₂C₆O₆ can be transferred from water to alcohol to induce self-assembly through intermolecular stacking interactions. The size of Na₂C₆O₆ can be controlled by adjusting the concentration of the starting materials and the volume ratio of water to alcohol.

[0088] The weight ratio between the carbon oxide salt and the functionalized carbon-based material (e.g., graphene oxide) within the composite electrode material can be selected to stabilize the electrode during cycling. In some embodiments of the composite electrode materials disclosed herein, the functionalized carbon-based material is loaded onto submicron particles of the carbon oxide salt. When selecting the weight ratio, factors such as the conductivity of the composite electrode material, the sufficiency of the active material (i.e., the carbon oxide salt), and the structural integrity during electrode fabrication can be considered. In some cases, the conductivity of the electrode material can adversely decrease if there is an excessive amount of functionalized carbon-based material, such as graphene oxide. Additionally, when the functionalized carbon-based material is graphene oxide, a high graphene oxide content can reduce the sufficiency of the active material (e.g., Na₂C₆O₆) and make it susceptible to cracking during electrode fabrication. If the graphene oxide content is too low, incomplete coverage occurs on the submicron particles of the carbon oxide salt (Na₂C₆O₆), and therefore stable resistance at ultra-low temperatures may not be achieved. Carbon oxide salts and graphene oxides can be present in the composite electrode material in a weight ratio of about 12:1 to about 2:1, such as 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, and 2:1. In some cases, the weight ratio between submicron particles of carbon oxide salts and graphene oxides is about 10:1 to about 3:1, or about 8:1 to about 4:1, for example, 5:1. When the composite electrode material consists of submicron particles of monocyclic alkali metal carbon oxide salts (e.g., Na₂C₆O₆) and graphene oxides, the weight ratio of carbon oxide salts to graphene oxides can be about 5:1.

[0089] In some cases, composite electrode materials also include functional materials, such as aerogels, which can contain various functional groups, such as hydroxyl, amino, and carboxyl groups. Aerogels include, but are not limited to, sodium alginate, chitosan, and agarose.

[0090] In some embodiments, composite electrode materials comprising carbon oxide salts and graphene oxide exhibit reduced contact angles and improved interfacial wettability compared to carbon oxide salts. The contact angle can be measured using sessiledrop analysis. For example, the liquid used to measure the contact angle is the electrolyte used in the examples, namely 1M NaPF6 in diethylene glycol dimethyl ether (DGM). Alternatively or additionally, electrodes prepared from the composite electrode material exhibit 119 mAh·g in a half-cell configuration at -50°C. -1 Significant capacity.

[0091] This article also discloses a method for preparing composite electrode materials, the method comprising: (i) Forming a first composition comprising a carbon oxide salt, water, and optionally an antisolvent; (ii) Forming a second composition comprising a functionalized carbon-based material, water, and an optional antisolvent; (iii) Mixing the first composition and the second composition to obtain the third composition; and (iv) Introducing a certain amount of antisolvent into the third composition under conditions that allow the formation of a precipitate containing submicron particles of the carbon oxide salt and the functionalized carbon-based material.

[0092] In some implementations, the method for preparing the composite electrode material includes: (i) Introducing a carbon oxide salt into a first mixture containing water and an antisolvent to obtain a first composition; (ii) Introducing a functionalized carbon-based material into a second mixture containing water and an antisolvent to obtain a second composition; (iii) Mixing the first composition and the second composition to obtain a third composition; and (iv) Introduce a certain amount of antisolvent into the third composition under conditions that allow the formation of precipitates containing submicron particles of carbon oxide salts and functionalized carbon-based materials.

[0093] It should be understood that the method can be used to prepare the composite electrode material as described above.

[0094] The antisolvents used in steps (i), (ii), and (iv) may be the same or different. In some embodiments, the antisolvents used in steps (i), (ii), and (iv) are preferably the same. When selecting the antisolvent used in the method, the solubility of the carbon oxide salt in each of the antisolvents and the miscibility between water and each of the antisolvents can be considered. The inventors propose that the carbon oxide salt may be less soluble or insoluble in each of the antisolvents compared to water, and that each of the antisolvents is miscible with water. There are no particular limitations on the antisolvents that can be used. Antisolvents other than those mentioned herein may also be considered for use in this disclosure. Antisolvents that can be used in this method include, but are not limited to, alcohols, ethers (e.g., diethyl ether), and / or ketones (e.g., acetone). For illustrative purposes, each of the antisolvents used in steps (i), (ii), and (iv) is an alcohol, such as methanol, ethanol, n-propanol, isopropanol, and / or isobutanol. When the ratio between the total amount of water and the total amount of antisolvent (e.g., alcohol) in the third composition is set, the particle size within the precipitate can be adjusted by changing the concentration of the carbon oxide salt based on the total amount of water and antisolvent in the third composition. When the concentration of the carbon oxide salt is set based on the total amount of water and antisolvent in the third composition, the morphology of the particles within the precipitate (e.g., rod-like morphology and diamond-like morphology) can be adjusted by changing the ratio between the total amount of water and the total amount of antisolvent (e.g., alcohol) in the third composition.

[0095] In some embodiments, a first mixture consisting of water and an antisolvent is used in step (i), and / or a second mixture consisting of water and an antisolvent is used in step (ii). For example, each of the first and second mixtures consists of water and an alcohol (such as ethanol).

[0096] For each of the first and second compositions in steps (i) and (ii), or for each of the first and second mixtures in steps (i) and (ii), the volume ratio of water to antisolvent may be ≥ about 1:1, ≥ about 1.5:1, for example, 2:1, 3:1, and 4:1. The content and amount of water component in the first composition or first mixture in step (i) are selected to ensure that the first composition or first mixture can completely dissolve the carbon oxide salt. The content and amount of water component in the first composition or first mixture in step (i) and the second composition or second mixture in step (ii) are selected to ensure that the carbon oxide salt is completely dissolved in the third composition, which is obtained by mixing the first composition and the second composition. There is no particular upper limit on the water to antisolvent ratio in the mixture. Water without antisolvent may be used in steps (i) and / or (ii). In some embodiments, the first composition or first mixture contains water and antisolvent in the same volume ratio as the second composition or second mixture. The first mixture may be the same as the second mixture. In a specific embodiment where ethanol is used as an antisolvent in steps (i) and (ii), the volume ratio of water to ethanol may be approximately 2:1. In a specific embodiment where each of the first and second mixtures used in steps (i) and (ii) consists of water and ethanol, the volume ratio of water to ethanol may be approximately 2:1.

[0097] The carbon oxide salt can be dissolved in the first composition (i.e., step (i)), and the graphene oxide can be dispersed in the second composition (i.e., step (ii)). For example, the carbon oxide salt is dissolved in the first mixture (i.e., step (i)), and the graphene oxide is dispersed in the second mixture (i.e., step (ii)). The first composition and / or the second composition can be formed by stirring or agitation. The carbon oxide salt and graphene oxide can be introduced into the mixture under stirring or agitation, for example, under ultrasonic treatment for about 10 to 20 minutes. Steps (i) and / or step (ii) can be carried out without additional heating, for example, at ambient temperature. For step (i), the amount and composition of the first mixture are selected to dissolve the carbon oxide salt. For step (ii), the amount and composition of the second mixture are selected to disperse the graphene oxide. For the methods disclosed herein, the total amount and / or composition of the first composition or first mixture used in step (i) and the second composition or second mixture used in step (ii) are selected to: (1) allow the carbon oxide salt to be completely dissolved in a third composition obtained by mixing the first and second compositions; and (2) provide a concentration of carbon oxide salt based on the total amount of the first and second mixtures to subsequently achieve a desired particle size and / or a desired particle morphology within the precipitate. In some embodiments, the total weight percentage of the carbon oxide salt introduced in step (i) is ≥ about 60% by weight, ≥ about 65% by weight, ≥ about 66% by weight, or ≥ about 67% by weight, based on the total weight of the first and second mixtures. For example, when each of the first and second mixtures contains water and an alcohol (e.g., ethanol), the carbon oxide salt introduced in step (i) is ≥ about 60% by weight (e.g., ≥ about 65% by weight, ≥ about 66% by weight, or ≥ about 67% by weight), based on the total weight of the first and second mixtures.

[0098] As described above, carbon oxide salts and functionalized carbon-based materials (e.g., graphene oxide) are used in weight ratios of about 12:1 to about 2:1, about 9:1 to about 3:1, or 8:1 to about 4:1. As an example, when the composite electrode material consists of submicron particles of a monocyclic carbon oxide alkali metal salt (e.g., Na2C6O6) and graphene oxide, the weight ratio of the monocyclic carbon oxide alkali metal salt to graphene oxide can be about 5:1.

[0099] After combining a first composition containing a carbon oxide salt and a second composition containing a functionalized carbon-based material (e.g., graphene oxide) to obtain a third composition, a certain amount of antisolvent is introduced into the third composition in step (iv) under conditions allowing precipitate formation. This is an antisolvent precipitation process, which can be controlled to adjust the particle size of the precipitate. If a smaller particle size precipitate is desired, conditions favorable to very rapid particle formation and little or no particle growth can be selected. The inventors propose that the amount of antisolvent introduced into the third composition significantly exceeds the total amount of water in the first and second compositions. The volume ratio of the amount of antisolvent introduced into the third composition to the total amount of water in the first and second compositions can be from about 6:1 to about 9:1, for example, about 6.5:1, about 7:1, about 7.5:1, about 8:1, and about 8.5:1. Step (iv), introducing a certain amount of antisolvent into the third composition under conditions allowing precipitate formation, can be carried out by means of a water bath and / or under stirring, for example, ultrasonic treatment. Conditions may include temperatures between about 0°C and about 70°C, such as about 20°C, about 25°C, or about 30°C. For example, in step (iv), a certain amount of antisolvent (e.g., alcohol) may be added to the third composition. In an embodiment, in step (iv), a certain amount of antisolvent (e.g., alcohol) may be added to the third composition in one step, which may result in the particles within the precipitate having or including a diamond-like morphology. Alternatively, in step (iv), the third composition may be added to a certain amount of antisolvent, which may result in the particles within the precipitate having or including a rod-like morphology and / or an irregular morphology. Due to the poor solubility of the salt in the water / alcohol mixture, the salt will begin to precipitate (preferably crystallize), then self-assemble into particles (preferably crystalline particles), and a functionalized carbon-based material (e.g., graphene oxide) will be loaded onto the carbon oxide salt particles (preferably crystalline particles).

[0100] Once a precipitate has formed, it can be collected and dried using any method known in the art. For example, the precipitate can be collected by centrifugation and dried in a vacuum oven.

[0101] The method may include other steps. For example, if the precipitate obtained from (iv) requires a crystalline state and the precipitate has not reached a crystalline state, the method may further include subjecting the precipitate to conditions that allow or improve the crystallization of carbon oxide salts. For this purpose, hydrothermal treatment, such as at about 180°C, may be employed.

[0102] If desired, the composite electrode disclosed herein can be prepared by antisolvent precipitation and solvothermal methods. In some embodiments, only water is used in steps (i) and / or (ii) without an antisolvent. For example, to prepare a composite electrode comprising rod-shaped Na₂C₆O₆ crystal particles and graphene oxide, an aqueous solution of Na₂C₆O₆ with graphene oxide dispersed is prepared, and then the solution is added dropwise to a large volume of alcohol (such as anhydrous ethanol) (e.g., at a volume ratio of 1:5). The mixture is allowed to stand for a period of time and then subjected to hydrothermal treatment, for example at about 180°C.

[0103] This disclosure also provides an electrochemical device comprising the composite electrode disclosed herein or a composite electrode obtained by the methods disclosed herein. The electrochemical device may be a storage battery or a battery, such as an ion battery.

[0104] This electrochemical device may be suitable for use under ultra-low temperature conditions. For example, the electrochemical device can operate at temperatures ≤ -30°C, ≤ -40°C, ≤ -50°C, ≤ -60°C, or ≤ -70°C. This enables it to withstand harsh conditions, such as the ultra-low temperatures of the deep sea.

[0105] Electrochemical devices incorporating the composite electrode materials disclosed herein can be designed and assembled using existing technologies. When selecting a cathode material, the following factors can be considered: (1) high electronic and ionic conductivity to ensure rapid electron and ion transport in the electrode material for excellent rate performance; (2) high sodium storage capacity for high reversible specific capacity; (3) high redox potential for high operating voltage; (4) excellent structural stability during charge and discharge for long cycle life; (5) high thermal and chemical stability for high safety; (6) good compatibility with the electrolyte to reduce side reactions at the electrode / electrolyte interface, thereby improving the coulombic ratio; and (7) low cost and environmental friendliness. The composite electrode material can be used as either a cathode or anode material.

[0106] For sodium-ion batteries that use composite electrode materials as the negative electrode material, the electrochemical device may include Prussian blue analogues (PBAs), such as MnFe-Prussian blue analogues (PBAs), as the positive electrode material. The general formula for PBAs is A. x P[R(CN)6]1 y · w H₂O, where A is an intercalated ion, usually potassium or sodium, and P and R are transition metals. y This refers to the number of [R(CN)6] vacancies. An example of a PBA that can be used is Na2MnFe(CN)6. In some embodiments, the composite electrode material consists of crystalline submicron particles of Na2C6O6 and graphene oxide.

[0107] For sodium-ion batteries that use composite electrode materials as positive electrode materials, the negative electrode materials can include, but are not limited to, reduced (Na4TP) sodium terephthalate, sodium metal, alloyed sodium metal, and graphite. In some embodiments, the composite electrode material consists of crystalline submicron particles of Na2C6O6 and graphene oxide.

[0108] For sodium-ion batteries, NaPF6 or NaClO4 can be used as the sodium salt and a suitable organic solvent that will not freeze at sub-zero or ultra-low temperatures to form the electrolyte. Organic solvents include, but are not limited to, dimethoxyethane (DME), diethylene glycol dimethyl ether (DGM), and carbonates such as propylene carbonate or ethylene carbonate, propylene carbonate, and methyl ethyl carbonate ternary mixtures. Examples of electrolytes include NaPF6 in dimethoxyethane (DME), NaPF6 in diethylene glycol dimethyl ether (DGM), and NaClO4 in an antifreeze modified ethylene carbonate / dimethyl carbonate (EC / DMC, 1:1 volume ratio) mixture.

[0109] In the manufacture of electrochemical devices, other components such as membranes, binders, conductive agents, and current collectors can be used. The membrane serves to provide a non-conductive barrier between the negative electrode (anode) and the positive electrode (cathode), while allowing ions to transport from one electrode to the other. It is desirable for the membrane to maintain chemical stability in the electrolyte while also exhibiting high affinity for it. Good mechanical stability is also desired. Non-limiting examples of membranes include glass fiber membranes, ceramic membranes, polyolefin membranes (e.g., porous polyolefin membranes), nonwoven membranes, and porous polymer membranes. A specific example is a polypropylene-polyethylene-polypropylene membrane, which is commercially available at Celgard®.

[0110] When powder materials are used in electrodes, binders can be incorporated into the electrodes to bind the various components together and provide a consistent mix of electrode components, thereby allowing the electrodes to conduct the required amount of electrons and ensuring electronic contact during the cycling of the electrochemical device. Non-limiting examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and carboxymethyl cellulose (CMC).

[0111] The primary function of conductive materials is to enhance the conductivity of electrodes. In some cases, the conductive agent used can be the same as that used in composite electrode materials. Non-limiting examples of conductive agents include carbon black, Ketjenblack, graphene, conductive carbon nanofibers (VGCF), carbon nanotubes (CNTs), and multi-walled carbon nanotubes (MWCNTs). In some embodiments, in addition to conductive materials combined with functional carbohydrates, conductive agents can also be introduced into the solid positive electrode.

[0112] A current collector is a bridging element that collects the current generated by the electrode and connects it to an external circuit. Current collectors have a significant impact on the capacity, rate performance, and long-term stability of electrochemical devices. Non-limiting examples of current collectors include aluminum (Al) foil, copper (Cu) foil, carbon-coated aluminum, carbon-coated titanium (Ti) foil, and carbon-based materials.

[0113] As an example, for manufacturing an electrode using the composite electrode material disclosed herein, a sub-DSR / GO composite material, carbon black (>99%, Alfa Aesar), and polyvinylidene fluoride (PVDF, Sigma) can be mixed in anhydrous N-methyl-2-pyrrolidone (NMP, Sigma, 99.5%) (e.g., a mass ratio of 70:20:10). The mixture is ball-milled and then coated onto aluminum foil. The composition is dried (e.g., under vacuum at 80°C). The mass loading of the sub-DSR / GO composite material can be 0.7 mg·cm⁻¹. -2 Up to 1.0 mg·cm -2 .

[0114] In some embodiments, the electrochemical device can achieve cycling stability of over 7000 cycles at approximately -40°C. Specifically, the electrochemical device can operate at 300 mA·g -1 High current density and maintains 101 mAh·g after 7000 cycles at approximately -40°C. -1 The discharge capacity. Alternatively or additionally, electrochemical devices can achieve a discharge capacity of 100 mA·g. -1 The current density and after 300 cycles at approximately -30°C showed 136 mAh·g -1 The capacity. Alternatively or additionally, in the case of an electrochemical device that is a pouch cell, the pouch cell can continuously power four light-emitting diodes (LEDs, 2.0V) for more than 1.5 hours at -50°C.

[0115] As should be understood from the above description, this disclosure also provides the use of composite electrode materials in the preparation of electrochemical devices and the use of composite electrode materials obtained according to the first aspect or the second aspect in electrochemical devices.

[0116] Example Material preparation Sodium submicron-sized rosinate (sub-DSR, Na) 2 C 6 O 6 Synthesis of ) DSRs of different sizes with rhombic morphology were synthesized using molecular self-assembly techniques and a solvent exchange process. Organic compounds were transferred from water (H₂O) to ethanol (EtOH) to induce self-assembly through intermolecular stacking interactions. The size of the DSRs was controlled by adjusting the concentration of the starting material and the volume ratio of H₂O to EtOH solvent. To prepare rhombic sub-DSRs, DSR (40 mg, sigma, purity: 97%) was dissolved in a mixture of H₂O and EtOH (2:1, total 60 ml) and stirred for 10 min. Subsequently, 300 ml of EtOH was added to the solution, and the mixture was sonicated in a water bath at approximately 20°C for 12 min. The experiment was conducted at ambient temperature without additional heating. The resulting reddish-purple precipitate was collected by centrifugation and further dried overnight in a vacuum oven at 60°C.

[0117] Synthesis of sub-DSR / graphene oxide (sub-DSR / GO) composite materials To prepare the sub-DSR / GO composite material, the same method was used, with the addition of monolayer GO (8 mg, GaoxiTech, 10 mg / ml) during the ultrasonic treatment step. Na4C6O6 was prepared by annealing DSR at 400°C for 3 hours under an Ar atmosphere, as previously reported. 29 Initially, a solvent mixture of 60 ml water / ethanol (2 / 1) was prepared. 40 mg of DSR was introduced into 30 ml of the solvent mixture to obtain the DSR composition, and monolayer GO (8 mg, GaoxiTech, 10 mg / ml aqueous dispersion) was added to another 30 ml of the solvent mixture to obtain the GO composition. The GO composition was sonicated for 10 minutes to achieve uniform dispersion. Subsequently, the DSR and GO compositions were mixed to obtain the DSR / GO composition and stirred for an additional 10 minutes. The DSR / GO composition was then sonicated in a water bath at ambient temperature for 12 minutes, while 300 ml of ethanol (EtOH) was added in a single batch. A precipitate formed, which was collected by centrifugation and dried overnight in a vacuum oven at 60°C.

[0118] Na 2 MnFe(CN) 6 Synthesis of (PBA) PBA was synthesized via a simple co-precipitation method. Specifically, Na₄Fe(CN)₆ (1.52 g) and NaCl (15 g) were dissolved in 100 ml of deionized (DI) water. MnCl₂ (0.63 g) was separately dissolved in another 50 ml of deionized water. The MnCl₂ solution was then added dropwise to the Na₄Fe(CN)₆ solution with stirring. The resulting suspension was aged for 2 hours and then separated by centrifugation. The obtained precipitate was washed three times with deionized water and dried under vacuum at 120 °C for 10 hours. The resulting sample was finely ground into powder for further use.

[0119] Sodium terephthalate (Na) 2 TP) 30 Synthesis Na₂TP was synthesized using a modified method based on a previously reported procedure. Terephthalic acid (1.73 g) was added to a hot solution (50 °C) of sodium hydroxide (1.38 g) in deionized water (5 ml). Subsequently, another 15 ml of deionized water was added to obtain a clear solution. The mixture was stirred for 30 minutes, and then ethanol (80 ml, EtOH) was added while continuously stirring at 70 °C for another 6 hours. The resulting precipitated crystals were collected and dried under vacuum at 150 °C for 1 hour. The counter electrode Na₄TP was prepared by complete discharge of Na₂TP in the presence of a Na foil.

[0120] Preparation of electrolytes All chemicals used in the preparation of the electrolyte were purchased from Sigma-Aldrich. Diethylene glycol dimethyl ether (DGM, anhydrous, 99.5%) was further dried for 12 hours using an activated 4 Å molecular sieve prior to use. Sodium hexafluorophosphate (NaPF6, 98%) was purchased and was ready for use without further treatment. In a typical procedure, NaPF6 (1.68 g) was dissolved in 10 ml of DGM at room temperature (RT). The electrolyte was stirred overnight and prepared for testing. All procedures were performed in a glove box filled with Ar (H2O < 0.5 ppm and O2 < 0.5 ppm).

[0121] Characterization methods Sample morphology was analyzed using a FEI Quanta 450 FEG scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of the sample powder were obtained using a Bruker D8 ADVANCE ECO X-ray diffractometer at 40 kV and 25 mA with Cu-Kα radiation (λ = 0.15418 nm). In-situ synchrotron soft X-ray spectroscopy (XAS) measurements were performed at the Australian Synchrotron Radiation Facility (ANSTO) in Melbourne. The acquired data were processed and analyzed using Igor Pro software. All samples for in-situ testing were thoroughly rinsed with DGM solvent to remove soluble substances from the electrode surfaces.

[0122] In situ Raman spectroscopy Raman spectroscopy was performed using a confocal Raman microscope (Renishaw, InVia™) with a 50X objective lens, and a 532nm laser was used at 100cm. -1 Up to 1800cm -1 The signal was recorded within the range. The laser power was maintained at 0.1%, and a diffraction grating of 1800 lines / mm was used.

[0123] In situ Fourier transform infrared spectroscopy (FTIR) In-situ FTIR measurements were performed on a Nicolet 6700. At 4000 cm⁻¹ -1 Up to 1200cm -1 Within a range of 4cm -1 The spectrum was collected by performing 64 scans in transmission mode at a resolution of 50 mA·g. -1 At a current density, a series of continuous in-situ spectral scans were collected every 2.5 minutes during constant current cycling. Automatic baseline correction and atmospheric compensation were performed using OMNIC software.

[0124] Electrochemical performance Electrochemical performance was evaluated using a 2032-type button cell. To fabricate the electrode, the synthesized sub-DSR / GO composite material, carbon black (>99%, Alfa Aesar), and polyvinylidene fluoride (PVDF, Sigma) were mixed in anhydrous N-methyl-2-pyrrolidone (NMP, Sigma, 99.5%) at a mass ratio of 70:20:10. The mixture was ball-milled at 400 rpm for 4 hours and then coated onto an aluminum foil with a diameter of 1.2 cm. After vacuum drying at 80 °C for 12 hours, the sub-DSR / GO loading was 0.7 mg·cm³. -2 Up to 1.0 mg·cm -2The sub-DSR control electrode and Na4TP counter electrode were prepared using the same procedure. For the PBA counter electrode, PBA powder, carbon black, and polytetrafluoroethylene (PTFE) binder (6% aqueous solution, Sigma-Aldrich) were mixed at a mass ratio of 70:20:10. The mixture was ground in an agate mortar with a few drops of ethanol, and then rolled into a self-supporting membrane. After vacuum drying at 80°C for 12 hours, the sample was cut into small pieces and attached to a stainless steel mesh. In the half-cell, fresh sodium metal and Whatman glass fiber were used as the negative electrode and separator, respectively. For the full cell, PBA or Na2TP was used as the counter electrode. All coin cells were assembled in an argon-filled glove box. Constant current cycling tests were performed at different rates and temperatures using a Land CT2001A and Newware battery testing system. Temperature variation tests were performed using a thermal testing chamber (GWS-MT3065 and HSLIF Husheng). Before starting the cryo-electrochemical tests, all cells were placed at low temperature for 5 hours. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) data were collected using an electrochemical workstation (BioLogic and CHI760E). EIS measurements were performed at an amplitude of 5 mV over a frequency range of 1 MHz to 0.01 Hz.

[0125] Determination of diffusion coefficient and activation energy The activation energy of the electrode can be calculated based on the thermal activation process. 31 (Equation S1) Where A0 is a constant, R is the gas constant, T is the Kelvin temperature, and E is the gas constant. a Indicates activation energy. Peak current (I) p The values ​​were obtained from the CV curves at different temperatures.

[0126] Results and Discussion Solid-liquid-solid conversion The redox reaction of the DSR organic electrode in Na + It occurs between the carbonyl group and the carbonyl group. 15 The Na|| sub-DSR half-cell was assembled from a Na foil negative electrode, a sub-DSR organic positive electrode, and a 1M NaPF6 electrolyte. The reaction process of the organic sodium-ion battery was monitored at room temperature (RT) by in-situ Raman spectroscopy, which offers high sensitivity for detecting transient substances. The Raman spectrum of the sub-DSR powder was observed at 100 cm⁻¹. -1 Up to 1800cm -1 It has multiple characteristics within the range ( Figure 7Figure 1a shows the evolution of the sub-DSR (300 nm to 500 nm) Raman spectra over time. After initial discharge to 1.7 V, all peaks disappeared, indicating the formation of an unstable and readily soluble substance in the ether-based electrolyte. 16 The dissolution of intermediates leads to the loss of active material in the sub-DSR electrode at room temperature and the absence of Raman activity in subsequent cycles. To reduce dissolution and fully utilize the material's capabilities, the sub-DSR was hybridized with GO. As shown in Figure 1b, the in-situ Raman 3D projection contour plot of the sub-DSR / GO composite electrode reveals reversible molecular structure changes with distinct Raman characteristics during cycling, indicating a highly reversible electrochemical process. Notably, no Raman activity was observed at the 1.7V discharge plateau (Figure 1c), corresponding to the formation of the Na4C6O6 intermediate. 17-20 The disappearance of the Raman peak indicates that the intermediate product Na4C6O6 on the electrode surface is soluble in the electrolyte, while the final products of discharge and charging remain in the solid phase and exhibit significant Raman activity. This reveals the solid-liquid-solid transformation reaction of the DSR electrode and provides valuable insights into its electrochemical behavior.

[0127] Electrochemical stability Figure 2a shows the discharge-charge curves of the bulk DSR, exhibiting a distinct discharge plateau at 1.7 V, corresponding to the intermediate product Na4C6O6. It can be synthesized according to previous reports (…). Figure 8 Upon immersion in DGM electrolyte, Na4C6O6 produces a yellow solution, while the original DSR (Na2C6O6) solution remains clear, as shown in Figure 2b. This is in excellent agreement with our Raman results, indicating that the intermediate is soluble at 1.7 V, involving a solution-mediated reaction. The dissolution of the active material adversely affects the cycling performance of the bulk DSR, with rapid capacity loss at 30°C due to active material depletion, as shown in Figure 2c. To address this challenge, a molecular self-assembly method was employed to prepare sub-DSR particles, as shown in Figure 2d. Particles of different sizes were synthesized by varying the initial volume of the H2O / EtOH solvent mixture (Figure 9). The charge storage of the DSR depends on the surface redox centers of the carbonyl group. Smaller particle sizes with increased contact area accelerate charge transfer and shorten the Na2C6O6 solution. + The diffusion pathway is improved, thereby enhancing the electrochemical performance of the DSR. To improve the cycling performance of the electrode, GO with a π-conjugated structure is introduced to modulate the molecular structural stability of the sub-DSR. SEM images of the sub-DSR / GO composite are shown in Figure 2e. For the initial cycling, at 300 mA·g... -1 At the given current density, after hybridization, the sub-DSR / GO exhibited a significantly improved capacity, reaching 333.7 mAh·g. -1(Based on the total mass of sub-DSR and GO), while the capacity of sub-DSR is 211.8 mAh·g in comparison. -1 Furthermore, the sub-DSR / GO composite material retains 98% of its capacity after 100 cycles, as shown in Figure 2f. Figure 10 shows optical images of the separators from the sub-DSR and sub-DSR / GO cells obtained after 3 cycles. GO in the composite electrode effectively anchors unstable intermediate organic matter to the electrode during cycling, resulting in a cleaner separator compared to sub-DSR. Therefore, the sub-DSR / GO composite electrode exhibits good performance at 1000 mA·g⁻¹. -1 It exhibits excellent stability after 500 cycles at high current density, with negligible capacity loss. Figure 11 Figure 12 shows the sub-DSR and sub-DSR / GO at 1000 mA·g. -1 The initial discharge-charge curves at high current densities are shown. Notably, the sub-DSR / GO exhibits a capacity of 317 mAh·g. -1 The high initial capacity indicates that a three-electron redox reaction occurred (the theoretical capacity of a four-electron redox reaction is 501 mAh·g). -1 ). Figure 13 Figure 15 shows further electrochemical tests of sub-DSR and sub-DSR / GO at room temperature. Here, the π-conjugation effect and abundant functional groups of GO contribute to the understanding of carbonyl redox processes (C=O). CO - The soluble substances produced in the process have a strong adsorption effect.

[0128] Interfacial and liquid phase transformation kinetics The sodium intercalation process in DSR proceeds via a solid-liquid-solid phase transition. The final discharge and charging products correspond to Na5C6O6 and Na2C6O6, respectively, existing as solid phases, while the intermediate product Na4C6O6 readily dissolves in ether-based electrolytes. Adsorption and transformation of soluble intermediates are two key strategies to prevent Na4C6O6 dissolution. To investigate the effect of GO incorporation on the reaction kinetics of the solution-mediated process, reactions were conducted at different temperatures ranging from -20°C to 25°C using 0.2 mV / s... -1Cyclic voltammetry (CV) measurements were performed on the sub-DSR and sub-DSR / GO electrodes at a scan rate of [missing value]. This study focuses on the characterization of the solution-mediated redox reaction (i.e., C2), which corresponds to the reduction peak at approximately 1.7 V, as marked in Figures 3a and 3b. According to the Arrhenius relation (Equation S1), the activation energy (Ea) associated with the C2 reduction process of the sub-DSR and sub-DSR / GO electrodes was determined by the slope of the peak current (Ip) versus the reciprocal of temperature (1 / T), as shown in Figure 3c. The calculated Ea values ​​for C1, C2, and C3 are shown in Table 1. Notably, the incorporation of GO leads to a decrease in the Ea of the C2 redox process, with a significant reduction in the energy barrier of approximately 25%. This is beneficial for the liquid-solid conversion process of C2. The insets in Figure 16 show the corresponding droplet contact angle measurements for the sub-DSR and sub-DSR / GO electrodes, respectively. After hybridization with GO, the composite electrode exhibits a significantly reduced contact angle, while interfacial wettability increases. The enhanced wettability of organic electrodes plays a crucial role in reducing battery resistance, which is caused by the reduced transport properties of the electrolyte and the stagnation of charge transport at low temperatures. Figure 17 shows the EIS measurements of the sub-DSR electrode and the sub-DSR / GO electrode over the temperature range of 25°C to -40°C. At -30°C, the sub-DSR electrode exhibits a lower Rw compared to the sub-DSR / GO composite. ct As shown in Figure 17a. However, when the temperature drops below -30°C, the R of the sub-DSR... ct It will increase significantly. Conversely, the R of sub-DSR / GO ct Only a small increase was observed from 25°C to -40°C (Figure 17b). This further confirms that the hybridization strategy of sub-DSR with GO primarily affects the activation energy of the electrode, resulting in relatively stable resistance and more efficient surface reactions at ultra-low temperatures. The enhanced reaction kinetics of the C2 process and the reduced Ea promote the transformation of the unstable intermediate phase. Therefore, dissolution is well regulated, which contributes to the excellent stability of the electrode at ultra-low temperatures.

[0129] Table 1. Fitting results of activation energies for different positive peaks of sub-DSR and sub-DSR / GO.

[0130]

[0131] Tunerable redox reactivity and stability of free radical intermediates Molecular and atomic structure analyses were performed using in-situ FTIR spectroscopy and out-of-situ synchrotron XAS. In-situ FTIR contour plots depict the molecular behavior of the sub-DSR electrode and the sub-DSR / GO electrode during the first two cycles. At approximately 1450 cm⁻¹... -1 and 1350cm -1The spikes observed at the locations correspond to the vibrations of C=O and CO stretching, respectively. 19、21-22 Due to the incorporation of GO, the position of C=O stretching in the composite material (e.g. Figure 18 (As shown) it moves to a lower wavenumber associated with the electron interaction of π-π stacking between the sub-DSR and GO. 23-24 Figure 3a shows the in-situ FTIR contour plot of the sub-DSR electrode, illustrating the continuous molecular structure evolution during cycling. The composite electrode exhibits a distinct molecular structure transition boundary between C=O and CO- (Figure 3b). The continuous changes observed in the sub-DSR indicate the occurrence of intermediate side reactions. Figure 3c shows the selected spectra from the in-situ test, demonstrating the pristine state, fully discharged state (1.0 V), and charged state (3.2 V) of the electrode during the first two cycles. During discharge, the intensity of the C=O band gradually decreases, while the intensity of the CO band gradually increases. This trend is reversed during the charging process of both electrodes. The reversible intensity change of the C=O vibration confirms the high reversibility of the redox reactions involving enolates and quinone carbonyls in the first two cycles. Notably, a 1550 cm⁻¹ is observed during the discharge process of the sub-DSR / GO electrode. -1 The broad peak in the vicinity can be attributed to the vibration of the C=C bond, which is absent in the sub-DSR electrode. 22 After initial sodium insertion, the organic molecule forms a free radical intermediate, with unpaired electrons located in the CO2 region. - The C atom is highly reactive and easily attacked by molecules in the electrolyte. Here, the π-conjugation interaction of GO effectively delocalizes the energy density of unpaired electrons on the C atom, significantly reducing side reactions on the C atom and resulting in a clear C=C band on the composite electrode. The limited reversibility observed in sub-DSR is primarily due to side reactions with the electrolyte. The π-conjugation effect of GO promotes rapid intermolecular electron transfer and enhances the tolerance of the organic electrode to ether electrolytes. Furthermore, Figures 3d to 3e and... Figure 19 Synchrotron soft XAS of sub-DSR powder and sub-DSR / GO powder is shown, as well as the CK edge of GO ( Figure 20 The XAS K-edge of O at both electrodes is similar to that of Na. However, the CK-edge at 287.3 eV (representing C1s-π) is different. (C=CO) Result 25-26 It exhibits a significant change after GO hybridization, with a decrease in intensity. This confirms the relationship with CO. - The reduced electron cloud density associated with the C atoms. Here, the conjugation of GO effectively modulates the redox reactivity and stability of DSR.

[0132] Electrochemical performance at ultra-low temperatures When exploring the low-temperature characteristics of organic electrodes, the Na storage performance of the half-cell coupled with Na metal was first evaluated at -30°C, such as... Figures 21 to 24 As shown. The composite electrode at 100 mA·g in the initial cycle. -1 An impressive 318 mAh·g was achieved at a current density. -1 High capacity. At an ultra-low temperature of -50℃, the Na||sub-DSR / GO half-cell can achieve a capacity of 50 mA·g. -1 Achieve 130mAh·g -1 The high capacity (Figure 5a) represents one of the best cryogenic performances for non-aqueous batteries. The corresponding galvanostatic discharge-charge curves shown in Figure 5b demonstrate stable capacity output with three distinct and flat discharge plateaus around 2.2V, 2.1V, and 1.8V throughout the cycle. Sub-DSR / GO shows great potential for cryogenic applications. However, due to the slow Na... + Due to diffusion and dendrite formation, Na metal anodes cannot achieve long-cycle performance at ultra-low temperatures. 27-28 Therefore, a full-cell configuration consisting of a sub-DSR / GO anode coupled with a MnFe-Prussian blue analogue (PBA) cathode is proposed, which exhibits exceptional long cycle life and is an automatic fault-tolerant device. An excess of PBA is used to satisfy the redox reaction of the organic electrode. Figure 5c shows the cycling performance of the sub-DSR / GO||PBA full cell at -40°C, at 100 mA·g. -1 Achieving 192 mAh·g at a current density -1 High initial capacity (based on sub-DSR / GO mass) and retains 138 mAh·g after 1000 cycles. -1 Furthermore, at 300 mA·g -1 At high current density, after 7000 cycles, the full battery still maintains 101 mAh·g. -1 The capacity (Figure 5c (illustration) and Figure 25 This is the best cycling performance ever reported at ultra-low temperatures. Figure 26 The rate performance of sub-DSR / GO||PBA at -40°C is shown, with the full cell even at 1000 mA·g -1 It can operate even at high current densities, exhibiting rapid kinetics. Furthermore, when the temperature is further reduced to -50°C, it still achieves 108 mAh·g in the first cycle. -1The discharge capacity was [not specified]. More importantly, the sub-DSR / GO||PBA full cell exhibited strong temperature resistance, as demonstrated by capacity recovery after a sudden increase in temperature from -50°C to room temperature and subsequent decrease to -40°C (Figure 5d). Figure 5e shows the corresponding discharge-charge curves of the full cell for different cycles at -50°C, indicating a clear voltage plateau with an average discharge voltage of 1.25V.

[0133] As shown in Figure 5f (Table 2), the sub-DSR / GO||PBA full cell exhibits excellent cycling electrochemical performance among reported non-aqueous cells at ultra-low temperatures. Figure 27a also shows the rate performance of the sub-DSR / GO-PBA full cell as a function of temperature. The corresponding EIS at different temperatures is shown in Figure 27b. Notably, even at -40°C, the full cell maintains a stable charge transfer resistance after hybridization with GO. This result is attributed to the GO-enhanced interfacial reaction kinetics and solution-mediated reaction kinetics. Furthermore, in addition to coupling with the high-voltage cathode PBA, an all-organic sodium-ion full cell utilizing a pre-cycled sodium terephthalate anode (Na4TP) was also assembled. This cell achieved a rate performance of 100 mA·g⁻¹. -1 The current density and after 300 cycles at -30°C exhibited 136 mAh·g. -1 The capacity (Figure 28). This is a good example of a sustainable battery composed only of C, O, and Na atoms. DSR's excellent low-temperature tolerance makes it a promising candidate for large-scale applications.

[0134] Table 2: Comparison of ultra-low temperature (-40℃ and below) performance of different non-aqueous batteries

[0135] Pouch battery characteristics at -50°C To demonstrate the feasibility of practical application of the sub-DSR / GO electrode under extremely cold conditions, a pouch cell coupled with a PBA positive electrode was assembled. Figure 6a shows a digital image of a single pouch cell exhibiting an open-circuit voltage of 2.1V in a fully charged state. Figure 6b shows the results at -50°C and 20mA·g. -1 The discharge-charge curves of the pouch cell, recorded at a current density of [value missing], show an average discharge voltage of 1.1V. The long-term cycling performance of the pouch cell is shown in Figure 6c. After 300 cycles, the capacity remains at 77 mAh·g. -1No significant capacity decay was observed. To highlight the potential of the sub-DSR / GO||PBA system in practical applications, as shown in Figure 6d, Figure 29, and the supporting video, two pouch cells connected in series demonstrated continuous power supply for four green LEDs (voltage requirement 2.0V) for over 1.5 hours, highlighting the enormous potential of the sub-DSR / GO||PBA system. The mass balance between the positive and negative electrodes can be further optimized to improve the overall cell energy density and cycle performance. This work represents a significant advancement in the search for reliable, high-performance battery systems suitable for extremely cold environments.

[0136] It should be understood that the terms “comprising” and “including” and any of their derivatives (e.g., including, containing, encompassing, including, enclosing) used in this specification shall be deemed to include the features referred to by the term and shall not exclude the existence of any additional features unless otherwise stated or implied.

[0137] Any reference to prior art in this specification is not, and should not be construed as, an admission or in any way an implication that such prior art constitutes part of common general knowledge.

[0138] Those skilled in the art will understand that the use of this disclosure is not limited to the specific applications or applications described herein. This disclosure is also not limited to preferred embodiments of the specific elements and / or features described or depicted herein. It should be understood that this disclosure is not limited to the one or more embodiments disclosed, but allows for many rearrangements, modifications, and substitutions without departing from the scope set forth and defined by the appended claims.

[0139] In some cases, for brevity and / or to aid in understanding the scope of this disclosure, a single embodiment may combine multiple features. It should be understood that in such cases, these multiple features may be provided individually (in individual embodiments) or in any other suitable combination. Alternatively, where individual features are described in individual embodiments, these individual features may be combined into a single embodiment unless otherwise stated or implied. This also applies to claims that can be recombined in any combination. That is, claims may be modified to include features defined in any other claim. Furthermore, the phrase referring to the list of items “at least one” means any combination of those items, including individual members. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc.

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Claims

1. A composite electrode material comprising submicron particles of carbon oxide salt and a functionalized carbon-based material.

2. The composite electrode material according to claim 1, wherein, The composite electrode material is a composite organic electrode material, which comprises the submicron particles of the carbon oxide salt and the functionalized carbon-based material, wherein the carbon oxide salt is derived from a natural source.

3. The composite electrode material according to claim 1 or 2, wherein, The functionalized carbon-based material is loaded onto the submicron particles of the carbon oxide salt.

4. The composite electrode material according to any one of claims 1 to 3, wherein, The functionalized carbon-based material includes graphene oxide or is graphene oxide.

5. The composite electrode material according to any one of claims 1 to 4, wherein, The carbon oxide salt comprises or is a monocyclic carbon oxide alkali metal salt.

6. The composite electrode material according to any one of claims 1 to 5, wherein, The carbon oxide salt comprises having the formula M m (CO) n Monocyclic carbon oxide alkali metal salts or those with formula M m (CO) n Alkali metal monocyclic carbon oxides (where M = Li, Na or K; 2 ≤ m ≤ 6; n = 4, 5 or 6).

7. The composite electrode material according to any one of claims 1 to 6, wherein, The carbon oxide salt comprises sodium rosinate (Na2C6O6) or is sodium rosinate (Na2C6O6).

8. The composite electrode material according to any one of claims 1 to 7, wherein, The submicron particles of the carbon oxide salt have a diamond-like morphology.

9. The composite electrode material according to any one of claims 1 to 8, wherein, The functionalized carbon-based material is graphene oxide, and the water solubility of the graphene oxide at room temperature is ≥ about 5 mg / ml.

10. The composite electrode material according to any one of claims 1 to 9, wherein, The carbon oxide salt and the functionalized carbon-based material are present in a weight ratio of about 12:1 to about 2:

1.

11. The composite electrode material according to any one of claims 1 to 10, wherein, The composite electrode material consists of submicron particles of a monocyclic carbon oxide alkali metal salt (e.g., Na2C6O6) and graphene oxide in a weight ratio of approximately 5:

1.

12. The composite electrode material according to any one of claims 1 to 11, wherein, The composite electrode material is used in electrochemical devices at temperatures ≤ approximately -30°C.

13. The composite electrode material according to any one of claims 1 to 12, wherein, The composite electrode material is used in electrochemical devices at temperatures ≤ approximately -50°C.

14. A method for preparing a composite electrode material, the method comprising: (i) Forming a first composition comprising a carbon oxide salt, water, and optionally an antisolvent; (ii) Forming a second composition comprising a functionalized carbon-based material, water, and an optional antisolvent; (iii) The first composition and the second composition are mixed to obtain a third composition; and (iv) Introducing a certain amount of antisolvent into the third composition under conditions that allow the formation of submicron particles containing the carbon oxide salt and the functionalized carbon-based material.

15. The method according to claim 14, wherein, The method includes: (i) Introducing a carbon oxide salt into a first mixture comprising water and an antisolvent to obtain the first composition; (ii) Introducing a functionalized carbon-based material into a second mixture comprising water and an antisolvent to obtain the second composition; (iii) Mixing the first composition and the second composition to obtain a third composition; and (iv) Introducing a certain amount of antisolvent into the third composition under conditions that allow the formation of submicron particles containing the carbon oxide salt and the functionalized carbon-based material.

16. The method of claim 14, wherein, The composite electrode material is the composite electrode material according to any one of claims 1 to 13.

17. The method according to claim 14 or 15, wherein, Each of the antisolvents used in steps (i), (ii), and (iv) is selected from alcohols, ethers, ketones, and combinations thereof.

18. An electrochemical device comprising a composite electrode material according to any one of claims 1 to 13 or a composite electrode material obtained by the method according to any one of claims 14 to 17.

19. Use of the composite electrode material according to any one of claims 1 to 13 or the composite electrode material obtained by the method according to any one of claims 14 to 17 in the preparation of an electrochemical device.

20. Use of the composite electrode material according to any one of claims 1 to 13 or the composite electrode material obtained by the method according to any one of claims 14 to 17 in an electrochemical device.

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