A magnetic field assisted lithium aluminum air battery and method of construction thereof

Abstract

The application discloses a kind of magnetic field auxiliary lithium aluminum air cell and its construction method, it belongs to battery technical field, wherein, the magnetic field auxiliary lithium / aluminum air cell includes: positive electrode material, diaphragm, negative electrode material, electrolyte and the magnetic field component for applying external magnetic field;Positive electrode material and / or the electrolyte include the metal magnetic material that is magnetically responsive with the external magnetic field.The magnetic field auxiliary lithium / aluminum air cell provided by the application, by external magnetic field orientation, constructs ordered magnetic structure, can in situ control the physicochemical characteristics of lithium / aluminum air cell discharge product, compared with traditional technology has significant advantages: on the one hand, overcome the defects such as structural control difficulty, complex process in the preparation of traditional magnetic catalyst;On the other hand, it can accurately break through the core bottleneck of metal-air battery reaction kinetics slow, not only realizes the dynamic controllable regulation of discharge product, and the whole process has the characteristics of environmental protection, simple, can significantly improve the catalytic activity of battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a magnetic field-assisted lithium-aluminum-air battery and its construction method. Background Technology

[0002] Metal-air batteries use metals such as lithium, zinc, and aluminum as the core of the negative electrode. They utilize oxygen in the air to undergo a reduction reaction at the positive electrode and achieve ion conduction through an organic or aqueous electrolyte. The basic structure consists of a negative metal electrode, a permeable positive air electrode, and an intermediate electrolyte layer. During operation, the negative metal undergoes an oxidation reaction to release electrons, which are then transferred to the positive electrode through an external circuit. At the same time, oxygen in the air undergoes a reduction reaction at the positive electrode, which, together with the directional migration of ions in the electrolyte, forms a closed loop to complete the output of electrical energy.

[0003] However, current metal-air batteries face multiple technical bottlenecks that severely restrict their performance improvement. On the one hand, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the positive electrode involve multiple electron transfer processes, resulting in slow reaction kinetics. This leads to a significant increase in overpotential and a substantial decrease in energy efficiency at high current densities, directly limiting power output and charge / discharge performance. On the other hand, insufficient electrode stability means that the metal negative electrode is prone to self-corrosion with the electrolyte, causing capacity loss. Furthermore, the air electrode catalyst is easily poisoned and deactivated by impurities such as CO2 and H2O or reaction intermediates in the electrolyte over long-term use. In addition, lithium-air batteries have a unique problem: their solid and insulating discharge products (such as Li2O2) continuously accumulate on the positive electrode surface, gradually clogging electrode pores and covering active sites, ultimately leading to positive electrode deactivation and structural damage. These problems collectively result in the low energy conversion efficiency of existing metal-air batteries, making it difficult to meet the large-scale commercial application requirements of electric vehicles and other fields with high demands for driving range and power output. This has become a core obstacle restricting technological breakthroughs.

[0004] Further research confirms that lithium peroxide (Li₂O₂) possesses an intrinsic magnetic moment due to the presence of unpaired electron spin, a characteristic that helps enhance electronic conductivity during its electrochemical formation and decomposition. Introducing metal guest ions can alter the magnetic structure of Li₂O₂ and precisely control the electron density near the Fermi level. However, traditional doping methods often result in uneven ion distribution on the surface of insulating discharge products, hindering their full effectiveness. Although existing research has attempted to introduce magnetic fields into battery systems to improve performance, conventional magnetic catalysts have inherent limitations: low magnetic field utilization efficiency, making it difficult to fully activate the catalytic effect of the magnetic field on the battery; more importantly, current technologies have not systematically explored the deep applications of magnetic fields in metal-air batteries. The failure to utilize the unique advantages of magnetic fields in dynamically controlling the magnetic behavior of magnetic catalysts and optimizing reaction intermediate conversion pathways has resulted in a persistent efficiency bottleneck in magnetic field-assisted technologies, failing to fundamentally solve the problem of limited battery performance.

[0005] The core challenges of magnetic field-assisted lithium / aluminum-air batteries lie in the insufficient synergy of the "magnetic field-catalyst-battery system" and the deep limitations of its mechanism of action. Existing magnetic catalysts are mostly simple doped magnetic particles, which, due to their low magnetic moment intensity and poor magnetic order, struggle to effectively couple with external magnetic fields. This low matching degree leads to insufficient magnetic field energy utilization, failing to fully activate key mechanisms such as magnetically mediated reaction kinetics and spin-selective orbital interactions, resulting in weak magnetic field assistance. Simultaneously, the regulation of the catalytic process by the magnetic field is mostly static, lacking the ability to dynamically adjust the magnetic behavior (such as magnetic moment orientation and magnetization) of the magnetic catalyst based on battery charging / discharging stages and current density changes. This leads to inaccurate optimization of reaction intermediate conversion pathways and the problem of sudden overpotential increases even at high current densities. Furthermore, there is a lack of systematic research on the core mechanisms of magnetic field assistance (such as magnetohydrodynamic mass transfer enhancement and spin polarization promoting charge transfer), and the synergistic effects between various mechanisms have not been explored. This limits the magnetic field's effect to a single stage, failing to achieve full-chain optimization of "charge transfer-reaction kinetics-mass transfer efficiency." Additionally, external magnetic fields readily interact with ions in the electrolyte (such as Li...). + Zn 2+ Interactions between the magnetic field and the aluminum-air battery can trigger side reactions (such as disrupted ion migration), and their impact on the corrosion behavior of the metal anode is not yet clear, potentially exacerbating anode self-corrosion and creating a system compatibility bottleneck. Furthermore, the introduction of a strong magnetic field requires a complex magnet structure, increasing battery size and cost, and making it difficult to ensure uniform magnetic field distribution (especially in large-scale battery packs), resulting in significant differences in catalytic performance across different regions, posing an obstacle to engineering applications. These pain points collectively prevent magnetic field-assisted technology from overcoming the dilemma of "limited efficiency improvement, insufficient stability, and excessive cost," thus failing to become a mature solution to the performance bottlenecks of lithium / aluminum-air batteries. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic field-assisted lithium / aluminum-air battery to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] A magnetic field-assisted lithium / aluminum-air battery includes a positive electrode material, a separator, a negative electrode material, and an electrolyte, and further includes:

[0009] Magnetic field assembly, used to apply an external magnetic field;

[0010] The positive electrode material and / or the electrolyte include a metallic magnetic material that responds magnetically to the external magnetic field; the metallic magnetic material is an oxide or metal salt of a magnetic metal.

[0011] Furthermore, the magnetic metal is one or more of Co, Fe, and Mn.

[0012] Furthermore, the magnetic field-assisted lithium / aluminum-air battery is a lithium-air battery; the electrolyte includes a metallic magnetic material; the metallic magnetic material is Co. 2+ Fe 3+ and Mn 2+ One or more metal salts.

[0013] Furthermore, the metallic magnetic material is one or more of CoCl2, FeCl3, and MnCl2.

[0014] Furthermore, the concentration of the metallic magnetic material in the electrolyte is 1-50 mg / mL.

[0015] Furthermore, the magnetic field-assisted lithium / aluminum-air battery is an aluminum-air battery; the positive electrode material includes a metallic magnetic material; the metallic magnetic material is one or more oxides of Co, Fe and Mn.

[0016] Furthermore, the metallic magnetic material is Co3O4.

[0017] Furthermore, the positive electrode material also includes a conductive agent; the mass ratio of the metallic magnetic material to the conductive agent is 1:(1.5-2.5).

[0018] Furthermore, the strength of the external magnetic field is 0.1-1 T.

[0019] Another object of the present invention is to provide a method for constructing the above-mentioned magnetic field-assisted lithium / aluminum-air battery, which includes the following steps:

[0020] Adding metallic magnetic materials to the electrolyte, or using metallic magnetic materials to prepare positive electrode materials;

[0021] A battery is assembled from positive electrode material, separator, negative electrode material and electrolyte;

[0022] By setting up a magnetic field assembly and placing the battery in an external magnetic field applied by the magnetic field assembly, a magnetic field-assisted lithium / aluminum-air battery is obtained.

[0023] The magnetic field-assisted lithium / aluminum-air battery provided by this invention constructs an ordered magnetic structure through external magnetic field orientation. Specifically, by introducing metallic magnetic materials into the cathode material or electrolyte, the physicochemical properties (such as crystal structure, electronic state, and magnetic properties) of the metal-air battery discharge products are controlled in situ by external magnetic field. This technology is a novel design and has significant advantages over traditional technologies: on the one hand, it overcomes the defects of traditional magnetic catalyst preparation, such as the difficulty in structural control and the complexity of the process, and realizes the simple integration of the catalyst and the battery system; on the other hand, the magnetic field-assisted metal-air battery constructed by this invention can precisely overcome the core bottleneck of slow reaction kinetics in metal-air batteries, not only realizing the dynamic and controllable regulation of discharge products, but also being environmentally friendly and simple throughout the process, and significantly improving the catalytic activity of the battery (such as reducing overpotential and accelerating ORR / OER reactions). Attached Figure Description

[0024] Figure 1 This illustrates the effect of magnetic metal ion concentration on the composition of discharge products in Example 1.

[0025] Figure 2 The X-ray photoelectron spectrum of the positive electrode of the magnetic field-assisted lithium-air battery discharge in Example 1 is shown, where a is Co 2p and b is Li 1s.

[0026] Figure 3 The image shows the in-situ UV-Vis spectrum of the magnetic field-assisted lithium-air battery during the charge and discharge process in Example 1. In this spectrum, a is the cyclic voltammetry (CV) curve, and b (Co 2p) and c (Li 1s) are the Co voltammetry curves. 2+ The standard UV-vis absorption curves of the ions are shown in d and e, respectively, which represent the UV-vis absorption spectra of the electrolyte during the discharge and charge reactions.

[0027] Figure 4 This refers to the current response of the magnetic field-assisted lithium-air battery in Example 1 under a constant magnetic field strength.

[0028] Figure 5 The graphs show the LSV curves of the magnetic field-assisted lithium-air battery in Example 1 under different magnetic field strengths, where a represents the discharge process and b represents the charging process.

[0029] Figure 6 The graphs show the deep charge-discharge curves of the magnetic field-assisted lithium-air battery in Example 1 and the non-magnetic field-assisted lithium-air battery in Comparative Example 1.

[0030] Figure 7 The images are scanning electron microscope (SEM) images of the positive electrode of the magnetic field-assisted lithium-air battery of Example 1 and the non-magnetic field-assisted lithium-air battery of Comparative Example 1 after discharge. In the images, a, b, and c are from Example 1, and d and e are from Comparative Example 1.

[0031] Figure 8 The image shows a scanning electron microscope (SEM) image of Co3O4 prepared in Example 2.

[0032] Figure 9 The diagram shows the power density of the magnetic field-assisted aluminum-air battery assembled in Example 2 under conditions with and without a magnetic field, where a represents the condition without a magnetic field and b represents the condition with a magnetic field.

[0033] Figure 10 The graph shows the discharge capacity of the magnetic field-assisted aluminum-air battery assembled in Example 2 under conditions with and without a magnetic field. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Metal-air batteries still face severe challenges. Lithium-air batteries are a typical example. Their discharge products (such as lithium peroxide, Li2O2) are insulating and poorly soluble in electrolytes. They form a dense coating on the electrode surface, which severely hinders the kinetics of redox reactions. This inhibits oxygen reduction (ORR) during discharge and also hinders the decomposition of discharge products (OER) during charging. This directly leads to battery capacity decay and power output reduction, greatly limiting overall performance.

[0036] To address the aforementioned problems, this invention constructs an ordered magnetic structure through external magnetic field orientation. This strategy enables precise control of the catalytic process using various magnetoelectric mechanisms, including accelerating reaction kinetics through magnetic mediation, enhancing charge transfer efficiency through magnetization, optimizing mass transfer processes based on magnetohydrodynamics, and strengthening reaction selectivity through spin-selective orbital interactions. This controllable magnetic structuring approach provides a highly promising solution for overcoming the inherent conductivity limitations of Li₂O₂, and is expected to fundamentally improve its electron transport performance in electrochemical processes.

[0037] To address this, an embodiment of the present invention designs a modified discharge product Li 2-x CoO2, which is produced by Co under the assistance of a composite magnetic field 2+ In-situ ion doping forms the structure. This process can induce a net magnetic moment and construct a ferromagnetically ordered structure, when Co... 2+ When ions are embedded in the Li₂O₂ matrix, their empty d orbitals interact with adjacent O atoms, driving the O₂... 2- / O2 -Charge redistribution and spin polarization within the framework ultimately lead to the formation of Co-doped Li with a modified electronic structure. 2-x O2 discharge products. The core innovation of this invention lies in the first demonstration that, through the synergistic effect of magnetic metal doping such as Co and an external magnetic field, short-range magnetic order can be induced in the discharge products of lithium-air batteries by leveraging the superexchange interaction between local Co magnetic moments. This technical solution has not been reported in existing technologies. Although there are studies on the application of magnetic fields in metal-air batteries in domestic and international literature and published patents, none have adopted this "doping-magnetic field" combination method, nor have they achieved similar synergistic performance improvement effects. In practical applications, this technology can effectively overcome the performance bottlenecks of existing metal-air batteries, not only significantly improving power output to meet the needs of high-power scenarios such as electric vehicles, but also improving charge and discharge efficiency and extending cycle life. Its applicability is wide-ranging, extending beyond lithium-air batteries to zinc-air, aluminum-air, and other battery systems. It also has significant application value in portable electronic devices, backup power supplies, and other fields, demonstrating outstanding practicality.

[0038] Specifically, the purpose of this invention is to provide an integrated solution based on "precise design of magnetic metal ion catalysts - dynamic control of magnetic field - synergistic optimization of battery system": By constructing novel magnetic discharge products with high magnetic moment order in situ, efficient coupling with external magnetic fields is achieved, improving magnetic field energy utilization; a dynamic magnetic field control strategy responsive to battery operating conditions (such as charge / discharge stages and current density) is developed to precisely optimize the conversion path of reaction intermediates; the synergistic effects of multiple magnetic field-assisted mechanisms (such as spin polarization, magnetohydrodynamic mass transfer, and magnetic catalysis) are systematically explored to achieve full-chain enhancement of "charge transfer - reaction kinetics - mass transfer efficiency"; simultaneously, the compatibility issues between the magnetic field and the electrolyte and metal anode are resolved, suppressing side reactions; and the engineering structure of magnetic field applications is simplified, reducing costs while ensuring uniform magnetic field distribution. Ultimately, this breakthrough overcomes existing technological bottlenecks, significantly improving the power output, energy efficiency, and cycle stability of lithium / aluminum-air batteries, promoting their large-scale application in electric vehicles, portable electronic devices, and other fields.

[0039] In one embodiment of the present invention, a magnetic field-assisted lithium / aluminum-air battery is provided, comprising a positive electrode material, a separator, a negative electrode material, and an electrolyte, and further comprising:

[0040] Magnetic field assembly, used to apply an external magnetic field;

[0041] The positive electrode material and / or electrolyte include a metallic magnetic material that responds magnetically to an external magnetic field; the metallic magnetic material is an oxide or metal salt of a magnetic metal.

[0042] In practical applications, the magnetic field component can be an electromagnet or other magnetic device, and the strength of the applied external magnetic field is preferably 0.1-1 T; the lithium / aluminum-air battery is a lithium-air battery or an aluminum-air battery, but is not limited to these.

[0043] Specifically, the magnetic metal is one or more of Co, Fe, and Mn, preferably Co.

[0044] In a preferred embodiment of the present invention, for the lithium-air battery system, the electrolyte includes a metallic magnetic material; the metallic magnetic material is Co. 2+ Fe 3+ and Mn 2+ One or more metal salts are used. Preferably, the metallic magnetic material is one or more of CoCl2, FeCl3, and MnCl2; more preferably, the metallic magnetic material is CoCl2. Furthermore, the concentration of the metallic magnetic material in the electrolyte is 1-50 mg / mL; the electrolyte can be a lithium bis(trifluoromethanesulfonyl)imide / dimethyl sulfoxide (LiTFSI / DMSO) organic solution, but is not limited to this, and other lithium salt electrolytes can also be used.

[0045] In another preferred embodiment of the present invention, for the aluminum-air battery system, the positive electrode material includes a metallic magnetic material; the metallic magnetic material is one or more oxides of Co, Fe, and Mn. Preferably, the metallic magnetic material is Co3O4, and the positive electrode material further includes conductive agents such as carbon nanotubes or conductive carbon black (Super P); the mass ratio of the metallic magnetic material to the conductive agent is 1:(1.5-2.5). Additionally, the positive electrode material also includes binders such as polyvinylidene fluoride, naphthol, or polytetrafluoroethylene. The preparation method of the positive electrode material is as follows: the metallic magnetic material and carbon nanotubes are mixed and dispersed in ethanol, and then an N,N-dimethylformamide solution of the binder is added and ultrasonically treated to obtain a slurry; the slurry is sprayed onto a current collector and dried to obtain the positive electrode material. It should be noted that the current collector can be, but is not limited to, hydrophobic carbon paper, carbon cloth, or nickel foam.

[0046] The magnetic field-assisted metal-air battery constructed in this invention employs an innovative design. Its core mechanism involves in-situ doping of discharge products using magnetic metals such as Co under a constant magnetic field. By dynamically controlling the magnetic domain distribution within the discharge products through an external magnetic field, a variable energy field can be constructed, thereby inducing the formation of a unique three-phase structure. The solution provided by this invention exhibits the following targeted advantages, achieving a breakthrough over traditional technological bottlenecks:

[0047] 1. Significantly improves magnetic field energy utilization efficiency, supporting the dynamic sustainability of catalytic reactions: This invention significantly improves the conversion efficiency of magnetic field energy to chemical energy by optimizing the coupling mechanism between magnetic components (such as precise screening and concentration control of specific magnetic metal ions) and the external magnetic field. Compared to the low magnetic field utilization rate in existing technologies, the magnetic ions in this system can form a directionally arranged "magnetically responsive microenvironment" under the action of the magnetic field, responding in real time to the dynamic needs of the ORR / OER reaction. It enhances oxygen adsorption and electron transfer during the discharge stage and accelerates product decomposition during the charging stage, achieving dynamic and continuous activation of the catalytic process and avoiding the limitations of "time lag" or "inefficiency" of magnetic field action in traditional technologies.

[0048] 2. Overcoming the performance bottleneck caused by discharge product coverage and accelerating electron transfer rate: Addressing the problem of solid insulating products (Li2O2) covering the catalyst and hindering the reaction in lithium-air batteries, this invention utilizes in-situ magnetic field control to regulate the growth path of discharge products. Through the synergistic effect of magnetic ions and the magnetic field, the products are induced to form modified morphologies with porous structures or high conductivity (such as the Co-doped Li2O2 mentioned above). 2-x O2, which possesses both magnetic and electronic conductivity, avoids the dense covering of active sites and promotes rapid electron transfer at the product-catalyst interface through magnetic moment coupling. This increases the electron transfer rate several times compared to traditional systems, meeting the core requirement of metal-air batteries for rapid electron transfer.

[0049] 3. Enhanced chemical stability of magnetic components to meet long cycle life requirements: Addressing the issue of existing magnetic catalysts being prone to hydrolysis and protonation deactivation in electrolytes, this invention improves stability through two methods: First, selecting magnetic ions (such as transition metal ions with specific valence states) with higher compatibility with the electrolyte (whether organic or aqueous) to reduce side reactions; second, optimizing the ion coordination environment induced by the magnetic field, enabling magnetic ions to form a more stable coordination structure during battery operation, reducing the probability of hydrolysis or protonation. This design significantly extends the catalyst's activity retention time, improving battery cycle life compared to traditional magnetic field-assisted systems, thus meeting the basic requirements for long-life applications.

[0050] In summary, the magnetic-assisted technology provided by the embodiments of the present invention precisely overcomes the core defects of the prior art through the synergistic design of "efficient magnetic energy utilization - dynamic product regulation - catalyst stabilization", transforming magnetic field assistance from "potential advantage" into "actual performance improvement", and ultimately achieving breakthrough improvements in key indicators such as discharge capacity, power output, and cycle stability of lithium / aluminum-air batteries, laying the core technical foundation for their large-scale application.

[0051] The following embodiments are some specific implementation examples of the present invention in practical applications, but are not limited thereto. It should be noted that the technical terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased on the market or prepared by existing methods.

[0052] Example 1: This example provides a method for constructing a positive electrode for a magnetic field-assisted lithium-air battery, including the following steps:

[0053] S1. Prepare 1 mol / L LiTFSI / DMSO organic solutions containing different concentrations (10, 25, 50 mg / mL) of CoCl2.

[0054] S2. Preparation of CNT / Pt: Carbon nanotubes (CNTs) were dispersed in 100 mL of ethylene glycol solution, and 1 mg of chloroplatinic acid (H2PtCl4) was added to obtain mixture A. The mixture was stirred vigorously at 170 °C for 3 hours, and the product was obtained by centrifugation at 8000 rpm for 5 minutes. The product was then washed repeatedly with deionized water and ethanol, and then dried under vacuum at 50 °C for 5 hours to obtain CNT / Pt.

[0055] S3. Disperse 100 mg of the CNT / Pt prepared above in ethanol and dilute to 50 mL. Then add 2.5 mL of N,N-dimethylformamide solution of polyvinylidene fluoride (PVDF) with a concentration of 2 mg / mL to obtain mixture B. Sonicate mixture B for 30 minutes to obtain CNT / Pt slurry. Spray the CNT / Pt slurry onto carbon cloth (10×10 cm), with a spraying area diameter of 1 cm and a loading of about 0.3 mg. After drying, obtain CNT / Pt positive electrode.

[0056] S4. Using CNT / Pt as the positive electrode, lithium metal as the negative electrode, and the prepared LiTFSI / DMSO organic solution as the electrolyte, and a glass fiber membrane as the separator, in a vacuum glove box, the lithium metal negative electrode is placed as the lower shell, and the glass fiber membrane and positive electrode are placed on top in sequence. Finally, 100 µL of electrolyte is added to fully wet the positive electrode and glass fiber membrane. The top shell of the coin cell is then placed on top, and the battery is sealed using a pressing machine to assemble a lithium-air battery. An external magnetic field (magnetic field strength of 300-530 mT) is applied to and not applied to the assembled lithium-air battery, respectively, and these are denoted as magnetic field-assisted lithium-air battery and lithium-air battery. The charge-discharge performance of the magnetic field-assisted lithium-air battery and the lithium-air battery is tested under the following conditions: current density 100 mA / g, cutoff voltage 2 V~4.5 V. The relevant test results are as follows: Figures 1-7 As shown.

[0057] Example 2: This example provides a method for constructing a positive electrode for a magnetic field-assisted aluminum-air battery, including the following steps:

[0058] S1. Prepare a 4 mol / L NaOH aqueous electrolyte.

[0059] S2. Preparation of Co3O4: 1.4 g of CoCl2·6H2O, 4.2 g of sodium acetate (CH2COONa), and 40 g of ethylene glycol (EG) were fully dissolved and transferred to a 50 mL reaction vessel. The vessel was then placed in a high-temperature oven and heated to 200 °C for 20 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature. The product was washed three times with ethanol and twice with water, dried at 60 °C, and then transferred to a muffle furnace. The furnace was calcined at 500 °C for 3 h at a rate of 5 °C / min to obtain flower-shaped Co3O4 microspheres. The scanning electron microscope image is shown below. Figure 8 As shown.

[0060] S3. 100 mg of carbon nanotubes (CNTs) and 50 mg of the Co3O4 prepared above were dispersed in ethanol and diluted to 50 mL. Then, 5 mL of a 2 mg / mL N,N-dimethylformamide solution of polytetrafluoroethylene was added to obtain a mixture. The mixture was ultrasonically treated for 30 minutes to obtain a CNT / Co3O4 slurry. The CNT / Co3O4 slurry was sprayed onto hydrophobic carbon paper (10 × 10 cm), with a spraying area diameter of 1 cm and a loading of approximately 1.5 mg. After drying, a CNT / Co3O4 cathode was obtained.

[0061] S4. Using the above-mentioned CNT / Co3O4 positive electrode as the positive electrode, metallic Al as the negative electrode, the above-prepared NaOH aqueous electrolyte as the electrolyte, and a glass fiber membrane as the separator, assemble them into aluminum-air batteries according to the method of Example 1. Apply and do not apply external magnetic fields (external magnetic field strength of 0.5 T) to both sides of the aluminum-air battery, respectively, and label them as aluminum-air battery and magnetically assisted aluminum-air battery. The relevant electrochemical performance tests are as follows: Figure 9 and Figure 10 As shown.

[0062] Comparative Example 1: This comparative example provides a method for constructing a magnetic field-free assisted lithium-air battery, including the following steps:

[0063] S1. Prepare a 1 mol / L LiTFSI / DMSO organic solution.

[0064] S2. Preparation of CNT / Pt: Carbon nanotubes (CNTs) were dispersed in 100 mL of ethylene glycol solution, and 1 mg of chloroplatinic acid (H2PtCl4) was added to obtain mixture A. The mixture was stirred vigorously at 170 °C for 3 hours, and the product was obtained by centrifugation at 8000 rpm for 5 minutes. The product was then washed repeatedly with deionized water and ethanol, and then dried under vacuum at 50 °C for 5 hours to obtain CNT / Pt.

[0065] S3. Disperse 100 mg of the CNT / Pt prepared above in ethanol and dilute to 50 mL. Then add 2.5 mL of N,N-dimethylformamide solution of polyvinylidene fluoride (PVDF) with a concentration of 2 mg / mL to obtain mixture B. Sonicate mixture B for 30 minutes to obtain CNT / Pt slurry. Spray the CNT / Pt slurry onto carbon cloth (10×10 cm), with a spraying area diameter of 1 cm and a loading of about 0.3 mg. After drying, obtain CNT / Pt positive electrode.

[0066] S4. Using CNT / Pt as the positive electrode, lithium metal as the negative electrode, the prepared LiTFSI / DMSO organic solution as the electrolyte, and a glass fiber membrane as the separator, in a vacuum glove box, the lithium metal negative electrode is placed as the lower shell, and the glass fiber membrane and positive electrode are placed on it in sequence. Finally, 100 µL of electrolyte is added to fully wet the positive electrode and the glass fiber membrane. The upper shell of the coin cell is then placed on top, and the battery is sealed using a tablet press to assemble a non-magnetic field assisted lithium-air battery.

[0067] 1. Confirm the concentration of CoCl2 additive in the electrolyte: by... Figure 1 X-ray diffraction (XRD) analysis was performed to test the effects of adding different concentrations of CoCl2 electrolyte (in the figure, without Co...). 2+ This represents Comparative Example 1 (a non-magnetic-assisted lithium-air battery without CoCl2), showing the composition changes of the discharge positive electrode products. The results show that when the CoCl2 additive concentration in the electrolyte exceeds 10 mg / mL, a LiOH phase appears in the discharge products of the electrode (i.e., some products are converted to LiOH). This indicates that excessive additives accelerate electrolyte decomposition, leading to the accumulation of byproducts; conversely, if the additive concentration is too low, insufficient catalytic active sites will cause a decline in battery performance.

[0068] II. Verification of successful control of doped products: Analysis Figure 2 X-ray photoelectron spectroscopy (XPS) data of Co obtained in Example 1 show that... 2+ In the catalyzed lithium-air battery system (with Co in the figure), the Co 2p orbital exhibits a clear characteristic peak shape, and peak fitting further confirms that its main oxidation state is Co.2+ (Peak positions are concentrated at 781.2 eV and 797.1 eV, corresponding to Co) 2+ The 2p3 / 2 and 2p1 / 2 orbitals indicate that Co 2+ It maintains a stable valence state and participates in the reaction system during catalysis. Figure 2 The peak-splitting results of the Li 1s spectrum in Figure b show that, for both the Co-doped system and the conventional discharge system prepared in Comparative Example 1 (without Co in the figure), obvious characteristic peaks appear at 55.15 eV and 55.24 eV. These two peak positions are Li in Li₂O₂. + With O2 2- The typical binding signal clearly confirms the formation of Li₂O₂ in the discharge products. Notably, compared to the conventional discharge cathode, the Li 1s binding energy of the Co-doped cathode shifts by 0.09 eV towards higher binding energies. This subtle but significant energy shift provides direct evidence of weak electronic interactions between Co and Li species, suggesting that Co… 2+ The introduction of Li changed + The surrounding electron cloud density may affect the local electronic environment of Li₂O₂ through coordination or charge redistribution. The above XPS results collectively indicate that Co... 2+ The successful incorporation of discharge products provided strong support, Co 2+ It not only participates in the oxygen redox cycle as an active species (such as promoting the reduction of O2 → Li2O2 and the oxidative decomposition of Li2O2), but also interacts with Li in the Li2O2 lattice. + By leveraging weak electron interactions, the electronic structure of Li2O2 can be modulated (e.g., adjusting the electron density near the Fermi level and inducing spin polarization), thereby optimizing the conductivity and reactivity of Li2O2 and laying the microstructural foundation for improving battery performance.

[0069] III. Quantitative Co 2+ Reversibility in battery cycling reactions: Analysis Figure 3 In-situ UV-Vis spectroscopy was performed using a three-electrode microcell (working electrode: CNT / Pt, loading 0.01 mg; counter electrode: Pt wire; reference electrode: Ag / AgCl) to monitor different Co concentrations in LiTFSI / DMSO organic solution. 2+ Changes in ion concentration. Figure 3 The cyclic voltammetry (CV) scan rate of a is 3 mV / s, and the potential is scanned from the open circuit voltage (OCV) to -2 V and then to 2 V. Figure 3 Co is shown in d and e. 2+The UV-Vis absorption spectra of the electrolyte in the catalytic battery during the discharge and charge reactions show that, in the ORR process (OCV → 2 V), the absorbance peaks at approximately 589 nm and 682 nm gradually decrease with increasing potential; conversely, in the OER process (2 V → OCV), these peaks partially recover, indicating that Co... 2+ Ions are regenerated. Utilizing... Figure 3 Co in b and c 2+ Quantitative analysis using the standard UV-Vis absorption curve of the ions revealed a conversion efficiency of 68.69%. This result confirms that the Co-containing... 2+ The oxygen conversion reaction in the electrolyte system exhibits good reversibility.

[0070] IV. Magnetic Response Characteristics: Analysis Figure 4 The magnetically assisted lithium-air battery system with CoCl2 added to the electrolyte exhibited significantly enhanced magnetic response characteristics under a 0.5T magnetic field, indicating the generation of higher-density high-energy carriers within the battery system during discharge. This phenomenon not only directly demonstrates the interaction between the magnetic field and CoCl2, but also... 2+ The strong coupling between them can also prove Co 2+ Under the influence of a magnetic field, the spin state of surrounding electrons may be altered through spin polarization, or the migration path of ions may be modulated through magnetic moment orientation, thereby improving the transport efficiency of charge carriers at the electrode-electrolyte interface. Simultaneously, the optimized magnetic properties of the discharge products induced by the magnetic field further reduce scattering losses during charge carrier transport, resulting in a higher density of high-energy charge carriers. These high-energy charge carriers can accelerate the adsorption and reduction of O2 during ORR and provide sufficient active charge for the subsequent OER process, ultimately leading to an overall improvement in battery reaction kinetics. This result confirms the role of Co in charge carrier behavior. 2+ The positive impact of magnetic field synergy on the battery system provides important experimental evidence for understanding the relationship between "macroscopic performance improvement and microscopic charge behavior" under the magnetic assistance mechanism.

[0071] V. Electrochemical reaction kinetics: Figure 5 To verify the effect of the magnetic field, ORR and OER performance were evaluated using a three-electrode system in a 1 mol / L LiTFSI electrolyte saturated with CoCl2 and O2, with a catalyst loading of 0.05 mg. Figure 5 As shown in Figure a, the battery under a magnetic field exhibits two distinct reduction peaks, corresponding to O2 and O2, respectively. - and Li 2-x The formation of CoO2. It is worth noting that increasing the magnetic field strength will increase the initial reduction of O2 to O2. - The current density, and the generation of Li 2-xThe initiation potential of CoO2 shifts positively. The maximum termination current density is positively correlated with the maximum magnetic field strength. Furthermore, as... Figure 5 As shown in b, the OER current density also exhibits a dependence on the magnetic field strength, increasing with increasing magnetic field strength. These results collectively indicate that the magnetic field modulates the Co content in the electrolyte. 2+ The behavior of ions optimizes the electrochemical pathway and accelerates the reaction kinetics of ORR and OER.

[0072] VI. Application Method: From Figure 6 The deep charge-discharge curves of the lithium-air battery show that at 0.4 mA / cm², the discharge rate is [not specified]. 2 At a current density of 100 mA / g, Co was added in Example 1. 2+ A lithium-air battery with a magnetic field applied (with Co in the figure) 2+ andM) exhibited the highest discharge capacity, reaching approximately 44.3 mAh / cm³. 2 (115918 mAh / g), while achieving 100% recharge reversibility. This capacity is approximately equivalent to that of the untreated lithium-air battery in Comparative Example 1 (without Co in the figure). 2+ ) and containing only Co 2+ However, lithium-air batteries without an applied magnetic field (with Co in the figure) 2+ 6 times and 10 times.

[0073] VII. Characterization of the growth behavior of discharge products in lithium-air batteries: Figure 7 The formation mechanism of discharge products was elucidated using ac, and the surface morphology of the positive electrode under three different conditions was observed using scanning electron microscopy (SEM). For example... Figure 7 As shown in a, when Co is added simultaneously 2+ Under the condition of applying a magnetic field, when the initial discharge capacity is 5 mAh, a unique nanoflower structure with a thickness of less than 30 nm is uniformly grown on the surface of the carbon fiber; when the discharge capacity increases to 10 mAh, a large number of spherical particles appear on the surface of the nanoflower. Figure 7 (b) filled the gaps in the spiderweb structure, indicating the occurrence of a secondary growth stage; further increasing the discharge capacity to 15 mAh, micron-sized cylindrical products were deposited on a spherical surface, exhibiting a disk-like morphology. These morphological changes clearly indicate that Co 2+ The synergistic effect with the magnetic field can dynamically regulate nucleation sites, promote the stepwise growth of three-phase discharge products, and thus significantly improve the battery's discharge capacity. For example... Figure 7 As shown in d and e, Co was not added. 2+ Or just add Co 2+ The battery's discharge products exhibit nanoparticles with a thickness of less than 100 nm and a large flower-like structure that completely covers the positive electrode, respectively.

[0074] The results above show that under the influence of a magnetic field, Co 2+ The performance of doped lithium-air batteries is significantly improved, thanks to the synergistic effect of the magnetic field and metal ions. This system brings several advantages: Co 2+ Ions in Li 2-x Atomic-level uniform doping is achieved in O2 discharge products; magnetic field-induced dp orbital hybridization improves electronic conductivity; Lorentz force generates a micro-region stirring effect; and the discharge products form a unique three-phase structure, greatly improving the battery's discharge capacity.

[0075] VIII. Applications of magnetically assisted aluminum-air batteries: such as Figure 8 As shown, the scanned image shows microsphere-shaped Co3O4, which forms a microsphere structure by self-assembly of nanosheets. This structure provides an ultra-large specific surface area and abundant active sites, significantly improving the adsorption and activation efficiency of O2.

[0076] like Figure 9 As shown in figures a and b, the aluminum-air battery system exhibits no significant difference in current density and power density under conditions with and without an external magnetic field (in the figures, "with magnetism" refers to the presence of an external magnetic field, and "without magnetism" refers to the absence of an external magnetic field). This indicates that the magnetic field does not significantly affect the battery's instantaneous output capabilities (such as instantaneous current intensity and power supply level). Further comparison of the discharge capacity of the two battery systems under the influence of a magnetic field (e.g.,...) Figure 10 As shown in the figure, it can be clearly observed that the discharge capacity of the battery is significantly higher when a magnetic field is applied. This phenomenon reveals that the magnetic field has a special role in the operation of aluminum-air batteries. Although it does not change the instantaneous output characteristics of the battery, it can effectively suppress the generation and accumulation of by-products on the surface of aluminum electrodes, reduce the ineffective consumption of aluminum active materials by side reactions, thereby extending the effective discharge time of the battery and ultimately achieving a significant improvement in discharge capacity. This also provides a new idea for optimizing the performance of aluminum-air batteries based on magnetic field regulation.

[0077] In summary, the significant effects of the magnetically assisted lithium / aluminum-air battery technology constructed in the embodiments of this invention are mainly reflected in three dimensions: performance improvement, fabrication optimization, and application expansion, as detailed below:

[0078] 1. The reaction kinetics are greatly accelerated. Through the synergistic effect of magnetic metal and external magnetic field, the physicochemical properties of discharge products (such as crystal structure, electronic conductivity and magnetic properties) are precisely controlled, which accelerates the multi-electron transfer process of the positive electrode ORR / OER. The overpotential of the positive electrode ORR / OER reaction is reduced, and the power output under high current density is increased by 2-3 times, which solves the pain point of "sharp drop in efficiency under high current conditions" of traditional batteries.

[0079] 2. Breakthrough improvements in capacity and cycle life: In-situ magnetic field control enables discharge products (such as Li2O2 and ZnO) to exhibit ordered structures (e.g., flower-like, porous structures), increasing the utilization rate of active sites; the magnetically assisted lithium-air battery achieves a discharge capacity of over 115918 mAh / g at a current density of 100 mA / g, with a rate performance of 6.7 A / g, and can stably cycle 188 times under low polarization conditions at a current density of 100 mA / g and a specific capacity limit of 1000 mAh / g; the magnetically assisted aluminum-air battery has a discharge capacity of 1 mA / cm². 2 The current density reached 144 mAh / g.

[0080] 3. Simplified process flow, eliminating the need for complex magnetic catalyst pre-preparation steps; only magnetic ions (such as Co) are added through the electrolyte. 2+ Fe 3+ By combining an external magnetic field, performance can be controlled, the preparation cycle is shortened, and the production cost is reduced, overcoming the shortcomings of traditional magnetic materials such as "difficult structural control and complicated process".

[0081] 4. Green and sustainable: The entire system avoids the use of precious metal catalysts or toxic solvents. Discharge products can be efficiently decomposed with the assistance of a magnetic field, reducing by-product pollution and meeting the development needs of environmentally friendly energy devices.

[0082] 5. Multi-system compatibility: The technical solution can be directly extended to various metal-air batteries such as lithium, aluminum, and zinc, and is suitable for different application scenarios (such as lithium-air batteries are suitable for electric vehicles with high energy density requirements, and aluminum-air batteries are suitable for low-cost backup power). It exhibits stable power output and energy efficiency in high-power demand scenarios (such as electric vehicles).

[0083] 6. Strong adaptability to working conditions: It can maintain stable performance in complex environments such as low temperature and high humidity, providing high-performance energy solutions for portable electronic devices, drones, emergency power supplies and other fields, and accelerating the practical application of lithium / aluminum-air batteries.

[0084] 7. Enhanced product regulation and stability: The ordered product structure induced in situ by the magnetic field reduces the disordered accumulation of insulating products, which not only improves the utilization rate of active sites but also optimizes the ion transport path, thereby increasing the battery discharge capacity and extending the cycle life.

[0085] 8. Mechanism Innovation and Universal Value: For the first time, the dynamic control of the entire chain of "ion-product-reaction" in metal-air batteries by magnetic field was realized, revealing the role of new mechanisms such as magnetic moment coupling and spin polarization in enhancing battery performance. It provides a reference for the "magnetic field-ion synergy" design concept for the performance optimization of other electrochemical energy devices (such as fuel cells and electrolyzers).

[0086] These effects break through existing technological bottlenecks in terms of performance, cost, and environmental friendliness, highlighting the innovation and practical value of magnetic-assisted technology in the field of metal-air batteries.

[0087] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A magnetic field-assisted lithium / aluminum-air battery, comprising a positive electrode material, a separator, a negative electrode material, and an electrolyte, characterized in that, Also includes: Magnetic field assembly, used to apply an external magnetic field; The positive electrode material and / or the electrolyte include a metallic magnetic material that responds magnetically to the external magnetic field; the metallic magnetic material is an oxide or metal salt of a magnetic metal; the magnetic metal is Co; When it is a lithium-air battery, the electrolyte includes a metallic magnetic material; the metallic magnetic material is CoCl2; the concentration of the metallic magnetic material in the electrolyte is 1-50 mg / mL; When it is an aluminum-air battery, the positive electrode material includes a metallic magnetic material; the metallic magnetic material is microsphere-shaped Co3O4; the positive electrode material also includes a conductive agent; the mass ratio of the metallic magnetic material to the conductive agent is 1:(1.5-2.5).

2. The magnetic field-assisted lithium / aluminum-air battery according to claim 1, characterized in that, The strength of the external magnetic field is 0.1-1 T.

3. A method for constructing a magnetic field-assisted lithium / aluminum-air battery as described in any one of claims 1-2, characterized in that, Includes the following steps: Adding metallic magnetic materials to the electrolyte, or using metallic magnetic materials to prepare positive electrode materials; A battery is assembled from positive electrode material, separator, negative electrode material and electrolyte; By setting up a magnetic field assembly and placing the battery in an external magnetic field applied by the magnetic field assembly, a magnetic field-assisted lithium / aluminum-air battery is obtained.

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