Cathodic material for rechargeable alkaline ion batteries

Abstract

The present invention relates to a cathodic material for batteries and to a method for obtaining same, wherein the cathodic material comprises crystalline zero-charge compound of formula [Fe2(CAN)3(H2O)x], wherein CAN is chloranilate and wherein x is 4 or 0. The invention also relates to a cathode and a rechargeable battery that comprise the cathodic material. Therefore, the invention belongs to the industry of energy, preferably renewable energy, more preferably rechargeable batteries.

Description

[0001] DESCRIPTION

[0002] Cathode material for alkali-ion rechargeable batteries

[0003] The present invention relates to a cathode material for batteries and its method of obtaining said cathode material comprises a zero-charge, crystalline compound of formula [Fe2(CAN)3(H2O) x ], where CAN is chloranilate and where x is 4 or 0. Furthermore, the invention relates to a cathode and a rechargeable battery comprising said cathode material.

[0004] Therefore, the present invention belongs to the energy industry sector, preferably renewable energy, more preferably rechargeable batteries.

[0005] BACKGROUND OF THE INVENTION

[0006] The growing energy demands of today's society and the need to mitigate global warming caused by the use of fossil fuels require the use of renewable energy sources to electrify the grid and transportation. Due to the intermittent nature of clean energy sources, these must be coupled with energy storage systems to maximize their use. Within this context, rechargeable batteries are flexible systems with diverse applications and high energy density. Therefore, battery production is increasing daily, and there are expectations of a growing need to develop thousands of tons of batteries to meet anticipated future demand.

[0007] The main components of the electrodes in high-energy-density rechargeable batteries contain critical, toxic, and difficult-to-obtain or extract elements, as they are geographically limited to a few countries, such as cobalt. Furthermore, the high energy cost required for mining some elements and chemical precursors, as well as the subsequent heat treatments applied to these precursors to obtain the final materials in the battery, can result in total energy consumption during production exceeding the energy these systems can store.

[0008] Metal-organic frameworks (MOFs) are promising candidates as battery cathodes. One of the emerging families of MOF-based cathodes are the A XM2Q3 (where A = alkylammonium cations; M = Fe, Mn, Zn, Co, Ni; and Q = dihydroxybenzoquinonate, chloranilate (CAN), and fluoranilate). These compounds form connected 2D honeycomb structures or interpenetrating cubic 3D hyperhoneycomb structures. The metals typically exhibit oxidation states M⁻¹ and M⁻¹. IH , while the quinonoid anion is often in its reduced form Q 3- or even Q 4- This requires the inclusion of alkylammonium counterions within the hexagonal holes to compensate for the charge and stabilize the anionic structure through electrostatic interactions (Ziebel, ME; Gaggioli, CA; Turkiewicz, AB; Ryu, W.; Gagliardi, L.; Long, JR. Effects of Covalency on Anionic Redox Chemistry in Semiquinoid-Based Metal-Organic Frameworks. J Am Chem Soc 2020, 142 (5), 2653-2664). These compounds are electrochemically active for the de / insertion of L +and anions. Specifically, 2D(H2NMe2)2[Fe2CAN3]-n DMF (dimethylformamide, DMF) reached a capacity of 147 mAh / g after 50 cycles at a current density of 40 mA / g (Ziebel, ME et al. J Am Chem Soc 2020, 142(5), 2653-2664; Dong, H. et al. Journal of Physical Chemistry C 2021, 125(38), 20814-20820), and has a high electronic conductivity of 2.6-10 3 S / cm.

[0009] However, the presence of additional weight in the form of counterions and solvent molecules is detrimental in terms of gravimetric specific capacity, since these add extra weight to the material, decreasing the charge storage capacity.

[0010] On the other hand, the document [JAMES T. WROBLESKI AND DAVID B. BROWN: "Synthesis, Magnetic Susceptibility, and Móssbauer Spectra of Iron(III) Dimers and Iron(II) Polymers Containing 2,5-Dihydroxy-1,4-benzoquinones". Inorganic Chemistry, Vol. 18, Pages 498-504] describes a material with the formula Fe2CA3(H2O)4-4H2O, which we can say has a supramolecular structure. Furthermore, this document describes the preparation of one-dimensional (1D) compounds with the composition {[M(CA)(H2O)2]H2O}n. This compound is also described in the document [MONTERO, JORGE et al.: "Lithium ion storage in 1D and 2D redox active metal-organic frameworks". Electrochimica Acta, 20200314 ELSEVIER, AMSTERDAM, NL, Vol. 341 ] where it is disclosed that by heating and dehydrating a Fe / CAN MOF (in different proportions) the structure is modified.However, it is indicated that when heating {[Fe(CA)(H2O)2]H2O]n it is possible to lose water molecules, but without knowing what happens to the crystalline structure or what happens to its eventual electrochemical properties, and it is not indicated at all that it is following the procedure described in the present invention or for obtaining the compounds of the present invention; in fact, it is indicated that after the heat treatment to which the crystalline structure of {[Fe(CA)(H2O)2]H2O}n is subjected, the electrochemical performance is modified and worsened from a capacity of 75mAh / g to a value of almost half (40 mAh / g).

[0011] Therefore, it is necessary to develop new cathode materials for rechargeable alkaline-ion batteries to maximize the use of renewable energy sources, achieving the highest possible capacity.

[0012] DESCRIPTION OF THE INVENTION

[0013] The present invention provides a cathode material for rechargeable batteries (hereinafter referred to as the cathode material of the present invention) characterized in that it comprises a zero-charge, crystalline compound of formula [Fe2(CAN)3(H2O) x ] where CAN is chloranilate and where x is 4 or 0. Note that the water in said formula is water ligand.

[0014] In the present invention, a “zero charge compound” is understood to be a compound that does not need counterions (positive or negative) to maintain electronic neutrality in the crystal lattice, with the positive charges of the metal being completely compensated by the negative charges of the organic ligand.

[0015] In the present invention, "specific gravimetric charge storage capacity" is understood to mean the amount of charge in coulombs (or electrons) per unit mass. If each Fe atom stores 1 electron and each ligand another electron, the counterions and solvent molecules present only contribute to the weight and not to the charge units, and therefore these counterions and solvent molecules decrease the specific gravimetric charge storage capacity.

[0016] The cathode material of the present invention exhibits a specific gravimetric charge storage capacity of 177 mAh / ga ​​C / 10, as it is a zero-charge material and contains no solvent molecules. Additionally, it exhibits greater stability than cathode materials containing solvents, since there is no risk of solvent loss during cycling. It should also be noted that the cathode material of the present invention comprises iron, which is the most abundant transition metal on Earth, and therefore its extraction is still sustainable.

[0017] The cathode material offers the advantage of being recoverable after use, allowing it to be reused in new rechargeable batteries and thus promoting its circularity. This is primarily due to its chemical stability in air, aqueous or alcoholic media, or mixtures thereof. The results (Figure 5) demonstrate that after galvanostatically cycling and subsequent exposure to air, the cathode material exhibits the structure with 8 water molecules of the precursor [Fe2(CAN)3(H2O)4]-4H2O.

[0018] In a preferred embodiment of the cathode material of the present invention, the neutral, crystalline metal-organic compound

[0019] • is [Fe2(CAN)3(H2O)4]

[0020] • It has a triclinic crystal structure

[0021] • and a 3D supramolecular network comprising dinuclear CAN-Fe- CAN-Fe-CAN species linked by hydrogen bonds.

[0022] Even more preferably, [Fe2(CAN)3(H2O)4] exhibits an X-ray diffractogram comprising the following hkl plane values, angles 20 ( e ) for CuK radiation a , interplanar distances d (Angstroms) and relative intensities (l / lo)*100, where the relative intensities are represented by f, m and d with values ​​of f = 80-100, m = 20-80 and d = 0-20.

[0023] These essential technical characteristics give it the following advantages:

[0024] • Reversible 4 Li insertion + The concentration of [Fe2(CAN)3(H2O)4] in its crystalline structure is determined by passing a specific current of 12.2 mA / g, resulting in a specific capacitance of 155 mAh / g and a specific energy of 400 Wh / kg. These properties are measured using galvanostatic cycling with a potential limit between 2V and 3.6V. + / L¡ using either of the two cathodes mentioned here as the working electrode, and using the lithium anode as the auxiliary and reference electrode, connecting the cell to a Biologic VMP3 multichannel potentiostat and using the equipment software.

[0025] • Reversible 3.8 Li insertion + The lithium in its crystalline structure is subjected to a specific current of 122 mA / g, resulting in a specific capacity of 126 mAh / g, a specific energy of 322 Wh / kg, and a specific power of 322 W / kg. After 500 cycles, it retains 80% of these initial capacity, energy, and power values. These properties are measured using galvanostatic cycling with a potential limit between 2-3.6 V vs Li + / L¡ using either of the two cathodes mentioned here as the working electrode, and using the lithium anode as the auxiliary and reference electrode, connecting the cell to a Biologic VMP3 multichannel potentiostat and using the equipment software.

[0026] In another preferred embodiment of the cathode material of the invention, the crystalline, neutral-charge metal-organic compound

[0027] • It is an anhydrous compound with the formula [Fe2(CAN)3]

[0028] • It has a rhombohedral R-3 crystal structure

[0029] • and an alternating ABC stacking of two-dimensional layers in the shape of a hexagonal honeycomb.

[0030] Even more preferably, [Fe2(CAN)3] exhibits an X-ray diffractogram comprising the following hkl plane values, 20 (°) angles for CuK radiation a, interplanar distances d (Angstroms) and relative intensities (l / lo)*100, where the relative intensities are represented by f, m and d with values ​​of f = 80-100, m = 20-80 and d = 0-20.

[0031] These essential technical characteristics give it the following advantages:

[0032] • Reversible 4.8 Li insertion + The [Fe2(CAN)3] ion was heated through its crystalline structure by passing a specific current of 14.7 mA / g, resulting in a specific capacitance of 177 mAh / g and a specific energy of 497 Wh / kg. These properties were measured using galvanostatic cycling with a potential limit between 2-4 V vs Li + / L¡ using either of the two cathodes mentioned here as the working electrode, and using the lithium anode as the auxiliary and reference electrode, connecting the cell to a Biologic VMP3 multichannel potentiostat and using the equipment software.

[0033] • Reversible 4.2 Li insertion + The crystalline structure of the lithium iron is subjected to a specific current of 147 mA / g, resulting in a specific capacitance of 153 mAh / g, a specific energy of 430 Wh / kg, and a specific power of 430 W / kg. After 100 cycles, it retains 84% ​​of these initial capacitance, energy, and power values. These properties are measured using galvanostatic cycling with a potential limit of 2-4 V vs. Li + / L¡ using either of the two cathodes mentioned here as the working electrode, and using the lithium anode as the auxiliary and reference electrode, connecting the cell to a Biologic VMP3 multichannel potentiostat and using the equipment software.

[0034] Another aspect of the present invention relates to the process for obtaining the cathodic material of the present invention, which is characterized in that it comprises the following steps: a) dissolving chloranilic acid (CANH2) in an alcohol at a temperature between 15 e C and 35 e C, preferably methanol or ethanol, b) adding an alcoholic solution of an iron precursor to the solution obtained in step (a), preferably the alcoholic solution comprises methanol or ethanol, c) centrifuging and decanting the precipitate obtained in step (b) by washing with alcohol, and d) heat-treating the product obtained in step (c) for a period of time between 10 minutes and 3 hours, and at temperatures between 60 e C and 100 e C in an oxidizing atmosphere, preferably the oxidizing atmosphere of step (d) is air.

[0035] Preferably, the iron precursor in step (b) is selected from ferrous nitrate, ferrous sulfate, and ferrous chloride. These precursors, like iron, are abundant in the earth and therefore their extraction is sustainable.

[0036] Preferably, step (d) is carried out in an air oven.

[0037] Another aspect of the present invention relates to the process for obtaining the cathodic material of formula [Fe2(CAN)3] characterized in that it comprises the following steps: a) dissolving chloranilic acid (CANH2) in an alcohol at a temperature between 15 e C and 35 eC, preferably methanol or ethanol b) adding an alcoholic solution of an iron precursor to the solution obtained in step (a), preferably the alcoholic solution comprises methanol or ethanol, c) centrifuging and decanting the precipitate obtained in step (b) by washing with alcohol, and d) heat-treating the product obtained in step (c) for a period of time between 10 minutes and 3 hours, and at temperatures between 60 e C and 100 e C in an oxidizing atmosphere, preferably the oxidizing atmosphere of step (d) is air, and e) heat treatment of the product obtained in step (d) for a period of time between 10 min and 3 h and in a temperature range between 150 e C and 170 e C in an oxidizing atmosphere, preferably the oxidizing atmosphere of step (e) is air.

[0038] Steps (d) and (e) are carried out independently, preferably in an air oven. This procedure allows the removal of all water, whether in ligand or cross-linked form, yielding an anhydrous compound [Fe2(CAN)3].

[0039] Another aspect of the present invention relates to the process for obtaining the cathodic material of formula [Fe2(CAN)3] characterized in that it comprises the following steps: a) dissolving chloranilic acid (CANH2) in an alcohol at a temperature between 15 e C and 35 °C, b) adding an alcoholic solution of an iron precursor to the solution obtained in step (a), c) centrifuging and decanting the precipitate obtained in step (b) by washing with alcohol, and d') heat treating the product obtained in step (c) for a period of time between 10 min and 3 h and in a temperature range between 150 e C and 170 e C in an oxidizing atmosphere, preferably the oxidizing atmosphere is air.

[0040] This procedure allows the removal of all water, whether in ligand or reticular form, obtaining an anhydrous compound [Fe2(CAN)3].

[0041] Furthermore, another aspect of the present invention relates to the cathode comprising the cathodic material of the present invention (hereafter the cathode of the invention).

[0042] The last aspect of the invention relates to a rechargeable battery comprising the cathode of the invention.

[0043] The rechargeable battery of the present invention offers the following advantages:

[0044] Its ability to reversibly (de)insert L ions + , Na + and K +The crystalline structure of the cathode material of the invention causes the rechargeable battery with a [Fe2(CAN)3(H2O)4] cathode and metallic anode to exhibit a specific energy of 400 Wh / kg cathode or 322 Wh / kg at a power of 322 W / kg, and the battery with a [Fe2(CAN)3(H2O)4] cathode to exhibit an energy density of 497 Wh / kg and 430 Wh / kg at a power of 430 W / kg. This battery could alternatively be assembled with a reversible insertion alkali-ion anode and using an organic electrolyte, either liquid or solid. Rechargeable batteries have a higher energy density than primary (non-rechargeable) batteries, and their recycling is more widespread than that of primary batteries, which are discarded at the end of their useful life, thus generating a large amount of waste. In any case, the recycling of currently marketed lithium-ion batteries is especially complicated and has not yet been standardized.Currently, various methods based on inefficient processes with a high environmental footprint are used, such as pyrometallurgical processes applied to the recovery of chemical elements like nickel and cobalt. Thanks to its physicochemical stability in air and alcoholic media, the cathode material of the present invention, and consequently the cathode and battery of the present invention, could be recycled using separation routes alternative to those described in the prior art, employing environmentally friendly, non-toxic, and low-cost solvents such as alcohols and bio-based ionic liquids, in the presence of air and applying low temperatures between 70°C and 70°C. e C and 170 eC, favoring the circular economy and therefore the environment throughout the recycling process. Briefly, the recovery of the cathode material, and therefore the battery cathode, could be separated from the other components, such as the binder present in the electrode formulation, by dissolving the latter in bio-based ionic liquids and / or alcohols in a first stage. In a second filtration stage, the precursor of the cathode material of the present invention would be recovered, which, after heat treatment, would be converted into the material with the formula Fe2(CAN)3.

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1. (a) Crystal structure of [Fe2(CAN)3(H2O)4] viewed along crystallographic axis b; (b) Crystal structure of [Fe2(CAN)3] in ABC layers.

[0047] Figure 2. Potential versus capacity of the material [Fe2(CAN)3] during a second cycle as a cathode versus lithium, sodium and potassium.

[0048] Figure 3. Comparative X-ray diffraction beams between compounds synthesized following the method of the invention and another compound (CP1-120) previously synthesized by a different method.

[0049] Figure 4. Electrochemical properties in a second cycle of [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] and of compound CP1 -120: (a) potential versus capacity; (b) differential capacity versus potential.

[0050] Figure 5. X-ray diffractograms of [Fe2(CAN)3] measured ex-situ protected from air after completing a galvanostatic discharge-charge cycle, [Fe2(CAN)3] measured ex-situ exposed to air after completing a galvanostatic discharge-charge cycle and [Fe2(CAN)3(H2O)4]-4H2O measured after synthesis.

[0051] PREFERRED EMBODIMENT OF THE INVENTION

[0052] The present invention is illustrated by the following examples, which are not intended to be limiting of its scope.

[0053] Example 1. Synthesis and characterization of [Fe2(CAN)3(H2O)4]

[0054] To synthesize the zero-charge, crystalline compound [Fe2(CAN)3(H2O)4], CANH2 (0.48 mmol, 195 mg) is dissolved in 10 ml of absolute EtOH in a vial at 20 e C and then a solution of [Fe] is slowly added drop by drop. IH [NO3]3-9H2O (1.44 mmol, 300 mg) in 2 ml of absolute EtOH to the CANH2 solution. The mixture is allowed to stand until the compound precipitates completely. The dispersion is then centrifuged and the supernatant decanted. This process is repeated three more times with the addition of alcohol (~5 ml) to remove any residual initial reagent. Finally, a heat treatment (heating) is performed for 1 h at 70 °C in an open-air oven to remove water from the crystal lattice.

[0055] The supramolecular structure of [Fe2(CAN)3(H2O)4] is obtained by ab-initio calculations and is composed of dinuclear monomers (CAN-Fe-CAN-Fe-CAN) linked by 3D hydrogen bonds and is also stabilized by TT stacking between CAN units. It contains similar channels, but along the b-axis instead of the c-axis, with a smaller size of 3.3 x 8.5 Å (Figure 1b).

[0056] The crystal structure of [Fe2(CAN)3(H2O)4] is determined by ab-initio calculations and subsequent Rietveld refinement of powder X-ray diffraction data at a temperature of 20 eC in a Bruker D8 Advance A25 diffractometer, with KCu, a1 = 1.54059 Å and KCu, a2 = 1.54432 Å radiation in a KCu, a1 / KCu, a2 ratio of 1:0.5. A triclinic crystal structure is observed, supported by 3D H bonds (Figure 1a). The powder diffractogram is shown in Figure 3 and the intensity values ​​assigned to the different reflections are tabulated below and presented in Table 1.

[0057] Table 1: Miller indices (hkl) of the reflections present in the crystal structure of [Fe2(CAN)3(H2O)4], with their corresponding positions indicated at 20° angles and interplanar distances, and their relative intensities.

[0058] The following measurements were performed to characterize the cathode material [Fe2(CAN)3(H2O)4]:

[0059] • measures of 57Fe-Mössbauer spectroscopy was performed at room temperature, in the velocity range of -4.5 to 4.5 mm s⁻¹, and in transmission geometry, using a spectrometer equipped with a 25 mCi 57Co-Rh source. The velocity was calibrated using the six-line magnetic spectrum of a high-purity iron foil absorber. The shift values ​​of the isomer (5) are given with respect to the body-centered cubic (bcc) Fe reference, and the spectra were fitted using the NORMOS fitting program.

[0060] Magnetic measurements were performed using an MPMS-XL SQUID magnetometer. Approximately 40 mg of sample was used. The Zero-Field Cooled-Field Cooled (ZFC-FC) technique was employed. First, the sample was cooled from 300 K to 2 K without applying a magnetic field. Once this temperature was reached, a magnetic field of 1000 Oe (0.1 T) was applied, and the susceptibility was measured while heating to 300 K. The sample was then cooled again to 2 K, this time with the field applied, and its magnetization was measured again by heating it from this temperature to a suitable temperature.

[0061] • Raman spectroscopy analysis of the samples. Raman spectra were taken with a Renishaw Raman microscope, using an Ar laser (515 nm)

[0062] • Analysis of the samples by UV / VIS spectroscopy. Ultraviolet-visible spectroscopy was measured with a Varian CARY 5G spectrophotometer.

[0063] By means of Móssbauer spectroscopy, magnetometry ( . e ff=5.7-5.9 MB / Fe 3+ ) and Raman spectroscopy it is determined that [Fe2(CAN)3(H2O)4] contains Fe and CAN in their highest oxidation states: +3 and -2 (HS-Fe 3+ and CAN 2 ~). The Fe +3 They are antiferromagnetically ordered at temperatures of 5-20 K due to the long Fe-Fe distance mediated by diamagnetic CAN ligands 2- .

[0064] From the UV-VIS spectroscopy measurements, it is concluded that the presence of bands at high energies (2.2; 3.4 and 4.5 eV) and the electronic conductivity measurements carried out by measuring I vs V in pellets of 10 mm diameter and 0.4-0.7 mm thickness, with a value of 2.5-10 10 S / cm at a temperature of 20 e C, indicate the insulating nature of the compound.

[0065] Example 2 Synthesis and characterization of [Fe2(CAN)3]

[0066] To synthesize the zero-charge, crystalline anhydrous compound [Fe2(CAN)3], CANH2 (0.48 mmol, 195 mg) is dissolved in 10 ml of absolute EtOH in a vial at 20 e C and then a solution of [Fe] is added drop by drop. IH [NO3]3-9H2O (1.44 mmol, 300 mg) in 2 mL of absolute EtOH to the CANH2 solution. The mixture is allowed to stand until the compound precipitates completely. The dispersion is then centrifuged and the supernatant decanted. This process is repeated three more times with the addition of approximately 5 mL of alcohol to remove any residual initial reagent. Finally, a heat treatment (heating) is performed for 3 h at 170 °C in an air oven to remove all water, whether in ligand or crosslink form.

[0067] The crystal structure of [Fe2(CAN)3] is obtained by ab-initio calculations and subsequent Rietveld refinement of powder X-ray diffraction data at a temperature of 20 eC in a Bruker D8 Advance A25 diffractometer, with radiation KCu,a1 = 1.54059 Å and KCu,a2 = 1.54432 Å in a KCu,a1 / KCu,a2 ratio of 1:0.5, is an alternating ABC stacking of 2D hexagonal honeycomb layers [Fe2(CAN)3] (Figure 1c), unlike other eclipsed stacked 2D hexagonal and interpenetrating 3D hexagonal arrangements. The absence of counterions leads to dense packing in which the neutral ABC layers interact via van der Waals forces. The Fe-Fe interlayer distance is 4.63 Å and the Fe-Fe intralayer distances are 7.77 Å for [Fe2(CAN)3].

[0068] The following measurements were performed to characterize the cathode material [Fe2(CAN)3]:

[0069] • measures of 57Fe-Mössbauer spectroscopy was performed at room temperature, in the velocity range of -4.5 to 4.5 mm s⁻¹, and in transmission geometry, using a spectrometer equipped with a 25 mCi 57Co-Rh source. The velocity was calibrated using the six-line magnetic spectrum of a high-purity iron foil absorber. The shift values ​​of the isomer (5) are given with respect to the body-centered cubic (bcc) Fe reference, and the spectra were fitted using the NORMOS fitting program.

[0070] Magnetic measurements were performed using an MPMS-XL SQUID magnetometer. Approximately 40 mg of sample was used. The Zero-Field Cooled-Field Cooled (ZFC-FC) technique was employed. First, the sample was cooled from 300 K to 2 K without applying a magnetic field. Once this temperature was reached, a magnetic field of 1000 Oe (0.1 T) was applied, and the susceptibility was measured while heating to 300 K. The sample was then cooled again to 2 K, this time with the field applied, and its magnetization was measured again by heating it from this temperature to a suitable temperature.

[0071] • Raman spectroscopy analysis of the samples. Raman spectra were taken with a Renishaw Raman microscope, using an Ar laser (515 nm)

[0072] • Analysis of the samples by UVVIS spectroscopy. Ultraviolet-visible spectroscopy was measured with a Varian CARY 5G spectrophotometer.

[0073] By means of Móssbauer spectroscopy, magnetometry ( . ef f=5.7-5.9 MB / Fe 3+ ) and Raman spectroscopy it is determined that [Fe2(CAN)3] contains Fe and CAN in their highest oxidation states: +3 and -2 (HS-Fe 3+ and CAN 2 -). The Fe +3 They are antiferromagnetically ordered at temperatures of 5-20 K due to the long Fe-Fe distance mediated by diamagnetic CAN ligands 2- .

[0074] Ultraviolet-visible spectroscopy, with the presence of bands at 0.9, 2.2, 3.4, and 4.0 eV; and electronic conductivity measurements performed by measuring I vs V in pellets 10 mm in diameter and 0.4-0.7 mm thick, point to a semiconductor behavior with an electronic conductivity of 4.9-10 7 S / cm at a temperature of 20 e C for the 2D structure of [Fe2(CAN)3],

[0075] Example 3: Electrochemical characterization of a cathode material comprising [Fe2(CAN)3(H2O)4] and a cathode material comprising [Fe2(CAN)3]

[0076] Galvanostatic cycling measurements are performed with potential limitation between 2-3.6 V vs Li + / L¡ for [Fe2CAN3(H2O)4] and between 2-4 V vs Li + / L for [Fe2CAN3], using either of the two cathodes mentioned here as the working electrode, and using the metallic lithium, sodium, or potassium anode as the auxiliary and reference electrodes. These measurements are performed by connecting the cell to a Biologic VMP3 multichannel potentiostat and using the instrument's software. [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] exhibit reversible electrochemical activity as cathode materials for rechargeable lithium, sodium, or potassium-ion batteries with the insertion of up to 5 L + , Na + or K + / fu, resulting in capacity values ​​in the range of 122–177 mAh / g, as well as a coulombic efficiency close to 100% (Figure 2). Due to its high average redox insertion potential (2.8 V vs. Li + / L¡), its high specific capacity value between 122 and 177 mAh / g, achieved as a result of the absence of solvent molecules and absence of counterions, in addition to the high oxidation state of the metal, Fe 3+ and the CAN ligand 2 ',

[0077] As shown in Figure 2 during the second cycle, a reversible capacity of 177 mAh / g vs Li, 162 mAh / g vs Na and 153 mAh / g vs K is maintained.

[0078] Example 4. Comparison of [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] with compound CP1-120 described in WO2023245949A1

[0079] WO2023245949 discloses a neutral, crystalline transition metal-quinone compound suitable for use as a cathode in lithium batteries and of general formula [M2(CA) X], where M is a transition metal such as Fe, Cu, Mn, Ni, CA is a disubstituted quinone from among 2,5-dihydroxy-p-benzoquinone; tetrahydroxy-p-benzoquinone; 2,5-dichloro-3,6-dihydroxy-p-benzoquinone; 2,5-dibromo-3,6-dihydroxy-p-benzoquinone and 2,5-difluoro-3,6-dihydroxy-p-benzoquinone, and x is 2 or 3.

[0080] To compare the cathode materials of the present invention with the materials disclosed in WO2023245949A1, the compound Fe2(CA)3, referred to herein as CP1-120, was synthesized and characterized.

[0081] To do this, 1 mol of 2,5-dichloro-3,6-dihydroxybenzoquinone (CANH2) and 2.5 mol of potassium hydroxide (KOH) are added to 1000 mL of water, at 25 eC. After the acid-base neutralization reaction is complete, an aqueous solution of the organic potassium salt (K₂CA) is obtained. Next, 150 mL of the K₂CA solution obtained in step (1) are mixed with 100 mL of a 1 mol / L aqueous solution of ferrous nitrate nonahydrate (Fe(NO₃)₃·9H₂O) to carry out a co-precipitation reaction in a 2:3 molar ratio (Fe / CAN), with magnetic stirring at 350 rpm for 6 hours. The reaction product is then centrifuged, washed three times with deionized water at 7000 rpm, filtered, and dried under vacuum at 120°C. e C for 12 hours.

[0082] Figure 3 shows the X-ray diffraction patterns obtained for the compounds [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] from Example 1, along with the pattern obtained for the material CP1-120, revealing that they correspond to different crystalline structures. In the case of CP1-120, its diffractogram was also obtained from powder X-ray diffraction data at a temperature of 20°C. eC in a Bruker D8 Advance A25 diffractometer, with radiation KCu,a1 = 1.54059 Å and KCu,a2 = 1.54432 Å in a KCu,a1 / KCu,a2 ratio of 1:0.5. The crystal structure of CP1-120 could not be refined by the Rietveld method, since it appears to correspond to a mixture of unknown phases, as indicated by the large number of reflections of varying widths present in the diffractogram. In any case, it is not either of the crystal structures corresponding to triclinic [Fe2(CAN)3(H2O)4] and rhombohedral R-3 [Fe2(CAN)3] from Example 1, since none of their reflections correspond to those in the CP1-120 diffractogram.

[0083] Figure 4a compares the alkali ion insertion potential against the charging capacity of the materials during the second cycle. It can be observed that compound CP1-120 exhibits a considerably lower capacity value than the compounds [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] from Example 1, which reach 155 and 177 mAh / g respectively in their second cycle at a cycling rate of C / 10, while CP1-120 only reaches 111 mAh / g. The electrochemical measurement was carried out by galvanostatic cycling with a potential limit between 1.7–4 V vs. Li + / L¡, in the same way as indicated in document WO2023245949A1 .

[0084] Figure 5 shows the derivative of capacitance versus voltage, and it can be seen that for [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] more intense redox processes appear in the 2.4-2.6 V region vs. Li + / L compared to those appearing in this same region for compound CP1-120, as well as a redox process at higher voltage exclusively for [Fe2(CAN)3], at 3.8 V vs Li + / L¡. Both higher intensity redox processes and higher voltage imply the ability to store a greater amount of energy.

[0085] Example 5: Comparison of [Fe2(CAN)3(H2O)4] and [Fe2(CAN)3] with the compounds {[Fe(CA)(H2O)2]H2O}n described in [MONTERO, JORGE et al.: "Lithium ion storage in 1 D and 2D redox active metal-organic frameworks". Electrochimica Acta, 20200314 ELSEVIER, AMSTERDAM, NL, Vol. 341]

[0086] In [MONTERO, JORGE et al.: "Lithium ion storage in 1 D and 2D redox active metalorganic frameworks". Electrochimica Acta, 20200314 ELSEVIER, AMSTERDAM, NL, Vol. 341], the authors report that the compound {[Fe(CA)(H2O)2]H2O}n, containing Fe and Mn, shows greater electrochemical activity than the 2D counterparts also reported in MONTERO, JORGE et al. with formulas [M(CA)(Pyz)]n and [M(DHBQ)(H2O)2]n, and that it reaches a maximum reversible capacity of up to 80 mAh / g. These currents were measured in Li-MOF half-cells subjected to cycling in a VMP multichannel potentiostat / galvanostat (Bio-Logic) operating at constant current densities (referred to as C rates: C / 20, C / 40, and C / 80). The average voltage is not specifically cited in Montero, Jorge et al., but it can be seen from the curves that it does not reach 2V.

[0087] In the present invention, the supramolecular material (0D) Fe2CA3(H2O)4, and the two-dimensional (2D) Fe2CA3, which have significantly higher reversible specific capacities of 146 mAh / g, and a much higher average voltage of 2.79 V compared to Li+ / Li, making them competitive cathode materials for alkali-ion batteries, far superior to that described in D01.

Claims

CLAIMS 1. Cathode material for rechargeable batteries characterized in that it comprises a zero-charge, crystalline compound of formula [Fe2(CAN)3(H2O)x], where CAN is chloranylate and where x is 4 or 0; where the zero-charge, crystalline compound • is [Fe2(CAN)3(H2O)4] • It has a triclinic crystal structure • and a 3D supramolecular network comprising dinuclear CAN-Fe-CAN-Fe-CAN species linked by hydrogen bonds; or where the zero-charge, crystalline compound • It is an anhydrous compound with the formula [Fe2(CAN)3] • It features an R-3 rhombohedral crystal structure and an alternating ABC stacking of two-dimensional layers in the form of a hexagonal honeycomb.

2. Cathodic material according to claim 1, wherein [Fe2(CAN)3(H2O)4] exhibits an X-ray diffractogram comprising the following hkl plane values, 20 (°) angles for CuK radiation a, interplanar distances d (Angstroms) and relative intensities (l / lo)*100, where the relative intensities are represented by f, m and d with values ​​of f = 80-100, m = 20-80 and d = 0-20.

3. Cathodic material according to claim 1, wherein [Fe2(CAN)3] has an X-ray diffractogram comprising the following values ​​of planes hkl, angles 20 (°), interplanar distances d (Angstroms) and relative intensities (l / lo)*100, wherein the relative intensities are represented by f, myd with values ​​of f = 80-100, m = 20-80 and d = 0-20.

4. Process for obtaining the cathode material according to any of claims 1 to 3 characterized in that it comprises the following steps: a) dissolving chloranilic acid (CANH2) in an alcohol at a temperature between 15 eC and 35 °C, b) adding an alcoholic solution of an iron precursor to the solution obtained in step (a), c) centrifuging and decanting the precipitate obtained in step (b) by washing with alcohol, and d) heat treating the product obtained in step (c) for a period of time between 10 minutes and 3 h, and in a temperature range between 60 e C and 100 e C in an oxidizing atmosphere or a temperature range between 150 e C and 170 e C in an oxidizing atmosphere, preferably the oxidizing atmosphere of stage (d) is air; and where if the temperature range of stage (d) is between 60 e C and 100 e Optionally, there is an additional step (e) of heat treatment of the product obtained in step (d) for a period of time between 10 min and 3 h and in a temperature range between 150 e C and 170 e C in an oxidizing atmosphere 5. Process according to claim 4, wherein the alcohol of step (a) and the alcohol of step (c) are independently selected from either methanol or ethanol.

6. A process according to any of claims 4 or 5, wherein the iron precursor of step (b) is selected from ferrous nitrate, ferrous sulfate, and ferrous chloride.

7. A cathode comprising the cathodic material according to any of claims 1 to 3.

8. Rechargeable battery comprising the cathode according to claim 7.

9. Battery according to claim 8, wherein the battery is a rechargeable L battery + , Na+ or K+.

10. A battery according to any of claims 8 or 9, wherein the battery is recyclable.

11. A battery according to any of claims 8 to 10, wherein the electrolyte can be solid or liquid.

Images