Application of a chiral photocathode catalyst for batteries and its preparation method

Abstract

This invention discloses the application of a chiral photocatalyst for batteries and its preparation method, belonging to the field of battery materials technology. The preparation method of the chiral photocatalyst includes: dispersing a Cd-based metal compound in a first solvent to obtain solution A; dispersing a chiral organic ligand in an alkaline solution to obtain solution B; wherein the chiral organic ligand is L-cysteine ​​or D-cysteine; and mixing solutions A and B to perform a self-assembly reaction to obtain the chiral photocatalyst. This invention is the first to propose the application of a chiral Cd-based photocatalyst in lithium / aluminum-air batteries. Its chiral structure endows the material with unique optical and electrical properties. Compared with ordinary Cd-based photocatalysts, it can efficiently separate photogenerated electron-hole pairs, reduce recombination rates, and selectively adsorb reactant molecules with specific configurations through its chiral structure, fundamentally changing the catalytic mechanism to promote ORR and OER reactions, significantly improving photocatalytic efficiency.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, specifically to the application of a chiral photocathode catalyst for batteries and its preparation method. Background Technology

[0002] Metal-air batteries typically use metals such as lithium, zinc, and aluminum as the negative electrode, while oxygen in the air undergoes a reduction reaction at the positive electrode. Ion conduction is achieved through an organic or aqueous electrolyte. The basic structure consists of a negative metal electrode, a permeable positive electrode, and an intermediate electrolyte. The working principle is that after the negative metal loses electrons through oxidation, they are transported through an external circuit, while oxygen undergoes a reduction reaction at the positive electrode, and ions migrate in the electrolyte to complete the output of electrical energy.

[0003] Existing metal-air batteries have significant technical bottlenecks. The slow reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the positive electrode, due to the multi-electron transfer process, restrict power output and charge-discharge performance, resulting in high overpotential and low energy efficiency at high current densities. At the same time, the metal negative electrode is prone to self-corrosion, causing capacity loss. The air electrode catalyst is prone to poisoning and deactivation after long-term use. In lithium-air batteries, the solid and insulating nature of the discharge products leads to positive electrode deactivation and structural damage. These problems make it difficult for the energy conversion efficiency of existing batteries to meet the large-scale application requirements of electric vehicles and other fields with high range and power requirements.

[0004] While photocatalysis technology has been widely applied in environmental purification and solar energy conversion, and although some studies have attempted to introduce photocatalysts into battery systems to improve performance, ordinary photocatalysts have inherent defects: high recombination rates of photogenerated electron-hole pairs, low efficiency in converting light energy into chemical energy, and simple coupling methods with electrodes, which cannot fully activate the photocatalytic assistance effect, resulting in insignificant performance improvement. More importantly, current technologies have not yet explored the application of chiral photocatalysts in metal-air batteries, failing to utilize the unique advantages of chiral structures in photogenerated carrier separation and selective adsorption of reactants, making it difficult to overcome the efficiency bottleneck of traditional photocatalytic assistance technologies.

[0005] Chiral photocatalysts address the core challenges of metal-air batteries, exhibiting performance advantages far exceeding those of ordinary photocatalysts and traditional catalysts. However, the immaturity of their preparation technology restricts their large-scale application. On the one hand, the precise control of chiral structure is extremely difficult, and existing methods such as template methods and asymmetric synthesis have significant limitations. Template methods rely on chiral molecule induction, but are prone to low chiral purity due to structural collapse in subsequent processing. Asymmetric synthesis methods are sensitive to the coordination balance between ligands and metal ions, easily forming racemic mixtures, making it difficult to stably prepare a single chiral configuration. On the other hand, the preparation process is complex and costly, requiring 5-8 steps including ligand dissolution, metal ion coordination, crystallization, chiral induction, and purification, with a reaction cycle of 7-14 days, resulting in low production efficiency. Furthermore, it relies on high-purity chiral raw materials, costing 3-5 times more than ordinary photocatalyst raw materials. Some toxic chiral ligands (such as chiral pyridine derivatives) also pose environmental risks, failing to meet the requirements for catalyst consistency in industrial battery production. Meanwhile, existing chiral photocatalysts exhibit high electron-hole recombination rates and insufficient light conversion efficiency, making them unable to participate in electrochemical reactions such as ORR / OER, far below the rapid electron transfer requirements of lithium / aluminum-air batteries. More importantly, in the electrolyte environment of lithium / aluminum-air batteries, the chiral ligands of existing chiral photocatalysts are prone to hydrolysis or protonation, leading to the disintegration of the chiral structure and failing to meet the long-life requirements of the battery. These defects make it difficult to achieve low-cost, high-stability large-scale production of chiral photocatalysts, collectively restricting their practical application in lithium / aluminum-air batteries and becoming a key obstacle to their application in metal-air batteries. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a chiral photocathode catalyst for batteries, so as 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 method for preparing a chiral photocathode catalyst for a battery includes the following steps:

[0009] A Cd-based metal compound is dispersed in a first solvent to obtain solution A;

[0010] A chiral organic ligand is dispersed in an alkaline solution to obtain solution B; the chiral organic ligand is L-cysteine ​​or D-cysteine.

[0011] Solution A and solution B were mixed and subjected to a self-assembly reaction to obtain a chiral photocathode catalyst.

[0012] Preferably, the Cd-based metal compound is a divalent Cd salt.

[0013] Preferably, the Cd-based metal compound is one or more of cadmium chloride, cadmium nitrate, and cadmium acetate.

[0014] Preferably, the molar ratio of the Cd-based metal compound to the chiral organic ligand is 1:(1-2).

[0015] Preferably, the first solvent is deionized water; the alkaline solution is an alkaline water system with a pH value of 8.0-10.0.

[0016] Preferably, the reaction temperature for the self-assembly reaction is 25-45 °C.

[0017] Another object of the present invention is to provide a chiral photocathode catalyst prepared by the above-described preparation method.

[0018] Another object of the present invention is to provide an application of the above-mentioned chiral photocathode catalyst in the preparation of metal gas batteries.

[0019] Another object of the present invention is to provide a metal gas battery, comprising a negative electrode, a separator, an electrolyte and a positive electrode, wherein the positive electrode is made of the above-mentioned chiral photopositive electrode catalyst.

[0020] Preferably, the method for preparing the positive electrode sheet includes the following steps:

[0021] The chiral photocathode catalyst is mixed with a binder and a second solvent to obtain a slurry;

[0022] The slurry is coated on both sides of the current collector and then dried to obtain the positive electrode sheet.

[0023] This invention provides a chiral photocatalyst for batteries, and for the first time proposes the application of chiral Cd-based photocatalysts in lithium / aluminum-air batteries. Its chiral structure endows the material with unique optical and electrical properties. Compared to ordinary Cd-based photocatalysts, it can efficiently separate photogenerated electron-hole pairs, reduce recombination rates, and selectively adsorb reactant molecules with specific configurations through its chiral structure, fundamentally changing the catalytic mechanism to promote ORR and OER reactions, significantly improving photocatalytic efficiency. In practical applications, this technology can significantly improve the power output of metal-air batteries to meet the high-power demands of electric vehicles, improve charge-discharge efficiency, and extend cycle life. It is applicable to various metal-air battery systems such as lithium, zinc, and aluminum, and also has significant application value in portable electronic devices, backup power supplies, and other fields, possessing outstanding practicality and promising to overcome the technical bottlenecks of existing metal-air batteries. Attached Figure Description

[0024] Figure 1Scanning electron microscope (SEM) images of the L-type chiral photoelectron catalyst prepared in Example 1, the D-type chiral photoelectron catalyst prepared in Example 2, and the LD-aachiral photoelectron catalyst prepared in Comparative Example 1, wherein a represents Example 1, b represents Example 2, and c represents Comparative Example 1.

[0025] Figure 2 X-ray diffraction patterns and X-ray photoelectron spectra of the L-type chiral photoelectron catalyst prepared in Example 1, the D-type chiral photoelectron catalyst prepared in Example 2, and the LD-ahidrotic photoelectron catalyst prepared in Comparative Example 1, wherein a is the X-ray diffraction pattern and b is the X-ray photoelectron spectrum.

[0026] Figure 3 The circular dichroic chromatograms are of the L-type chiral photoelectrode catalyst prepared in Example 1, the D-type chiral photoelectrode catalyst prepared in Example 2, and the LD-ahidrotic photoelectrode catalyst prepared in Comparative Example 1.

[0027] Figure 4 The solid UV-Vis diffuse reflectance spectra of the L-type chiral photoelectrode catalyst prepared in Example 1, the D-type chiral photoelectrode catalyst prepared in Example 2, and the LD-ahidrotic photoelectrode catalyst prepared in Comparative Example 1.

[0028] Figure 5 The graphs shown are the charge-discharge plateau curves and cycle curves of the lithium-oxygen battery assembled with the L-chiral catalyst in Example 1 under conditions of no light irradiation. In the figure, a is the charge-discharge plateau curve and b is the cycle curve.

[0029] Figure 6 The image shows a scanning electron microscope (SEM) image of the positive electrode of the lithium-oxygen battery assembled with the L-type catalyst in Example 1 after discharge under both light and dark conditions, where a represents the light condition and b represents the dark condition.

[0030] Figure 7 The diagram shows the power density of the aluminum-air battery assembled with the L-type chiral catalyst in Example 1 under both light and dark conditions, where a represents the dark condition and b represents the light condition.

[0031] Figure 8 The graphs show the charge-discharge plateau curves and rate curves of the aluminum-air battery assembled with the L-type chiral catalyst in Example 1 under both light and dark conditions. Here, a is the charge-discharge plateau curve and b is the rate curve. Detailed Implementation

[0032] 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.

[0033] The slow electrode reaction kinetics in metal-air batteries significantly limit their power output and charge / discharge performance. Constructing light-assisted metal-air batteries can effectively enhance the electrochemical reaction kinetics, helping to overcome current technical bottlenecks and opening new avenues for performance improvement.

[0034] In view of the shortcomings of the prior art, the purpose of the embodiments of the present invention is to:

[0035] (1) A method for preparing a chiral photocathode catalyst for lithium / aluminum-air batteries is provided. This method has the characteristics of simple process, environmental friendliness, low cost and high catalytic efficiency. It utilizes the chiral structure characteristics to efficiently separate photogenerated electron-hole pairs and reduce recombination rate. At the same time, it accelerates ORR and OER processes and improves reaction kinetic performance by selectively adsorbing reactant molecules with specific configurations.

[0036] (2) By using the chiral photocathode catalyst to regulate the structure of discharge products of lithium-air batteries, the photocatalytic effect can be fully utilized to improve the power output, charge-discharge efficiency and cycle stability of lithium / aluminum-air batteries.

[0037] (3) Expand the application system of photocatalysts to solve the problems of low energy conversion efficiency and poor stability of existing lithium / aluminum-air batteries, and promote their practical application in electric vehicles, portable electronic devices and other fields.

[0038] Specifically, in this embodiment of the invention, a chiral photocathode catalyst for metal-air batteries is prepared by mixing a Cd-based metal compound with chiral L- and D-type chiral cysteine ​​ligands to form a multidentate coordination-driven chiral self-assembly. The core of this catalyst is Cd. 2+ It forms stable coordination bonds with chiral sites and functional groups in L-cysteine ​​molecules, and constructs an ordered structure through chiral transfer. During assembly, when Cd... 2+ After mixing solution (solution A) with alkaline cysteine ​​solution (solution B), Cd 2+ Prefers to react with the sulfhydryl group (-S) in L-cysteine - ) combined with (the lone pair of electrons of the S atom in Cd) 2+ Affinity is much higher than Cl - and O atom), while amino group (-NH3) + The N atom and carboxyl group (-COO)- The O atom serves as an auxiliary coordination site to form a five-membered chelate ring, yielding a chiral photocatalyst. This preparation method is a novel design that overcomes the shortcomings of traditional chiral catalyst preparation, such as difficulty in structural control and complex processes. More importantly, the chiral photo-assisted metal-air battery constructed using the method provided in this invention can overcome the bottleneck of slow reaction kinetics in lithium-air batteries. It not only achieves efficient, environmentally friendly, and simple preparation of chiral photocatalysts but also significantly improves the catalytic activity of the battery, providing an innovative solution for optimizing the performance of metal-air batteries.

[0039] In one embodiment of the present invention, a method for preparing a chiral photocathode catalyst for a battery is provided, comprising the following steps:

[0040] S1. Disperse the Cd-based metal compound in the first solvent to obtain solution A;

[0041] S2. Disperse the chiral organic ligand in an alkaline solution to obtain solution B; the chiral organic ligand is L-cysteine ​​or D-cysteine;

[0042] S3. Mix solution A and solution B to carry out a self-assembly reaction to obtain a chiral photocathode catalyst with a twisted structure. The volume ratio of solution A to solution B is 4:6-6:4.

[0043] Specifically, the Cd-based metal compound is a divalent Cd salt, preferably one or more of cadmium chloride (CdCl2), cadmium nitrate (Cd(NO3)2·4H2O), and cadmium acetate (Cd(CH3COO)2·2H2O); during the self-assembly reaction, the driving force of intermolecular interactions is utilized, due to Cd... 2+ Ions with empty valence orbitals can act as "metal centers" to accept electron pairs; while chiral organic ligand molecules contain functional groups that can provide lone pairs of electrons, acting as "coordination sites" with Cd. 2+ Coordination bonds are formed. Through the spontaneous coordination of "coordination bonds-secondary interactions-chirality transfer" between molecules, high-purity and high-stability chiral structures can be precisely constructed.

[0044] In a preferred embodiment of the present invention, the molar ratio of the Cd-based metal compound to the chiral organic ligand is 1:(1-2). The core function of the Cd-based metal compound and the chiral organic ligand is to transfer chirality to the entire assembly through an asymmetric structure, and the 1:(1-2) ratio enables the "directional alignment" of the ligands. The two chiral ligands and Cd... 2+During coordination, due to their asymmetric structures (such as the steric hindrance of R-configuration ligands), they will align along the same chiral direction (clockwise / counterclockwise) to form a helical coordination framework, ensuring efficient chiral transfer from ligands to assemblies. If the ratio is too high (such as 1:3), excessive ligands will insert into the gaps in the coordination framework, disrupting the chiral orientation consistency of adjacent ligands (some ligands may be arranged in opposite directions), leading to disordered chiral transfer and racemization of the assembly. If the ratio is too low, the number of ligands is insufficient to form a continuous chiral framework, and the chiral signal intensity will decrease significantly.

[0045] In a preferred embodiment of the present invention, the first solvent is deionized water; the alkaline solution is an alkaline water system with a pH of 8.0-10.0, and the pH of the system stabilizes at 7.5-9.0 after mixing; the reaction temperature for the self-assembly reaction is a constant temperature water bath at 25-45℃, with magnetic stirring at 300-500 rpm, and the reaction time is 4-12 hours. Cd-based metal compounds (such as Cd(NO3)2, CdCl2) are polar salts with high solubility in water and can dissociate into free Cd. 2+ This provides a sufficient source of metal ions for the coordination reaction; however, using organic solvents such as methanol or ethanol will lower the Cd content. 2+ The degree of dissociation leads to a decrease in the coordination reaction rate, and residual organic solvent may interfere with the weak interactions of subsequent chiral structures. Solution B uses an alkaline aqueous system as the solvent, which promotes the dissociation of functional groups of chiral organic ligands. Simultaneously, water, as a solvent, can form hydrogen bonds with the ligands, assisting in the directional alignment of the chiral ligands and avoiding ligand aggregation caused by the organic solvent. The dissociation of chiral ligands and Cd... 2+ The stability of Cd is extremely sensitive to pH. When the pH of solution B is < 8.0, the functional groups of the ligands such as -COOH and -NH2 are not completely dissociated, resulting in insufficient free coordination sites and incomplete coordination reactions; when the pH of solution B is > 10.0, Cd... 2+ Will react with OH - The combination generates Cd(OH)2 precipitate, consuming available Cd. 2+ This disrupts coordination equilibrium, and the precipitate can encapsulate unreacted ligands, leading to disordered chiral structures. After mixing solutions A (neutral, pH≈7.0) and B (pH=8.0-10.0) in equal proportions, the pH of the system naturally adjusts to 7.5-9.0. At this point, Cd... 2+ It avoids precipitation, allows for complete ligand dissociation, and ensures efficient chiral transfer as the spatial orientation of the chiral ligands remains unaffected by pH. However, excessively low reaction temperatures (e.g., room temperature 25°C) reduce the rate of molecular thermal motion, leading to Cd... 2+ Insufficient collision frequency with ligands prolongs the self-assembly reaction cycle to over 24 hours, and the assemblies are prone to forming amorphous structures due to incomplete reactions; excessively high temperatures (e.g., >60℃) will destroy the interaction between the ligands and Cd. 2+The stability of coordination bonds can be compromised, potentially leading to the thermal decomposition of chiral ligands and the collapse of the chiral framework. At a reaction temperature of 40-50℃, molecular thermal motion and coordination bond stability reach equilibrium, shortening the reaction cycle. Too low a stirring rate (<200 rpm) will result in uneven mixing of solutions A and B, leading to excessively high local concentrations (e.g., Cd). 2+ Localized excess can trigger non-specific aggregation, forming particles with large size differences (particle size distribution span > 100 nm); excessively high stirring rates (> 800 rpm) can generate strong shear forces, disrupting weak interactions between ligands (such as hydrogen bonds and π-π stacking), thus hindering the lateral stacking of chiral assemblies and preventing the formation of a three-dimensional network structure. A stirring speed of 300-500 rpm can achieve macroscopically uniform mixing of the solution while avoiding the disruption of weak interactions by microscopic shear forces.

[0046] In another embodiment of the present invention, a metal gas battery is also provided, comprising a negative electrode, a separator, an electrolyte, and a positive electrode, wherein the positive electrode is made of the above-described chiral photopositive catalyst.

[0047] In practical applications, metal gas batteries include lithium-oxygen batteries and aluminum-air batteries, but are not limited to these.

[0048] Specifically, the preparation method of the positive electrode sheet includes the following steps: mixing the chiral photocatalyst with a binder and a second solvent to obtain a slurry; coating the slurry on both sides of the current collector, and then drying it to obtain the positive electrode sheet.

[0049] Preferably, the mass ratio of the chiral photocathode catalyst to the binder is 4-6:1-2; the binder is selected from, but not limited to, polyvinylidene fluoride, naphthol, or polytetrafluoroethylene; the second solvent is selected from, but not limited to, ethanol, N-methylpyrrolidone, N,N-dimethylformamide, water, or toluene; and the current collector is selected from, but not limited to, carbon paper, carbon cloth, or nickel foam.

[0050] In this embodiment of the invention, the provided chiral photocathode catalyst, with its unique chiral structure, can efficiently separate photogenerated electron-hole pairs, reducing the electron-hole recombination rate compared to ordinary photocatalysts and significantly improving light energy conversion efficiency. Simultaneously, it exhibits selective adsorption capacity for specific configurations of oxygen molecules and ORR / OER reaction intermediates, effectively accelerating the reaction process and enhancing the positive electrode reaction kinetics of the battery, fundamentally improving the reaction kinetics performance of lithium / aluminum-air batteries. This chiral photocathode catalyst demonstrates high stability, reducing the risk of poisoning and deactivation of air electrode catalysts, while also inhibiting self-corrosion of the metal negative electrode. Battery cycle life is increased to 2-3 times the original, and the actual usable capacity is significantly increased. It is not only suitable for common metal-air batteries such as zinc-air and aluminum-air batteries, but can also be extended to other systems, playing a highly efficient and stable power supply role in portable electronic devices, backup power supplies, and other fields, promoting the commercial application of metal-air batteries. In addition, the embodiments of the present invention adopt a self-assembly method, which does not require complex templates and harsh reaction conditions. By controlling the molar ratio of Cd-based metal compounds to chiral organic ligands and the reaction conditions, chiral structures can be accurately constructed. The process is simple, low-cost, highly efficient, and easy to scale up, overcoming the defects of traditional chiral catalyst preparation.

[0051] The following embodiments are some specific implementation examples of the present invention in practical applications, but are not limited thereto.

[0052] Example 1: This example provides a method for preparing an L-type chiral photocathode catalyst, comprising the following steps:

[0053] S1. Disperse CdCl2 in deionized water to prepare 10 mL of 0.1 mol CdCl2 aqueous solution, denoted as solution A;

[0054] S2. Disperse L-cysteine ​​in deionized water to prepare 10 mL of 0.1 mol L-cysteine ​​aqueous solution, and add 1 mL of 1 mol / L NaOH aqueous solution to adjust the pH value to obtain solution B;

[0055] S3. Mix the above solutions A and B in 100 mL of aqueous solution and carry out a self-assembly reaction at 30 °C and 400 rpm with magnetic stirring for 6 h to obtain a turbid solution. Cool the turbid solution to room temperature and centrifuge at 8000 rad / min for 10 min to remove the supernatant and obtain a white solid product. Then wash the solid product with deionized water and ethanol by centrifugation several times and place the solid product in a vacuum drying oven to dry at 80 °C for 12 h to obtain an L-type chiral photocathode catalyst, denoted as L-CST.

[0056] Example 2: This example provides a method for preparing a D-type chiral photocathode catalyst, including the following steps:

[0057] S1. Disperse CdCl2 in deionized water to prepare 10 mL of 0.1 mol CdCl2 aqueous solution, denoted as solution A;

[0058] S2. Disperse D-cysteine ​​in deionized water to prepare 10 mL of 0.1 mol D-cysteine ​​aqueous solution, and add 1 mL of 1 mol / L NaOH aqueous solution to adjust the pH value to obtain solution B;

[0059] S3. Mix the above solutions A and B in 100 mL of aqueous solution and carry out a self-assembly reaction at 30 °C and 400 rpm with magnetic stirring for 6 h to obtain a turbid solution. Cool the turbid solution to room temperature and centrifuge at 8000 rad / min for 10 min to remove the supernatant and obtain a white solid product. Then wash the solid product with deionized water and ethanol by centrifugation several times and place the solid product in a vacuum drying oven to dry at 80 °C for 12 h to obtain a D-type chiral photocathode catalyst, denoted as D-CST.

[0060] Example 3: This example provides a method for preparing a chiral photocathode catalyst, including the following steps:

[0061] S1. Disperse Cd(NO3)2·4H2O in deionized water to prepare 10 mL of 0.1 mol Cd(NO3)2 aqueous solution, denoted as solution A;

[0062] S2. Disperse L-cysteine ​​in a certain concentration of NaOH aqueous solution to prepare 10 mL of L-cysteine ​​aqueous solution with pH = 9 and a concentration of 0.15 mol, to obtain solution B;

[0063] S3. Mix the above solutions A and B in 100 mL of aqueous solution and carry out a self-assembly reaction at 35 °C and 400 rpm with magnetic stirring for 8 h to obtain a turbid solution. Cool the turbid solution to room temperature and centrifuge at 8000 rad / min for 10 min to remove the supernatant and obtain a white solid product. Then wash the solid product with deionized water and ethanol by centrifugation several times and place the solid product in a vacuum drying oven to dry at 80 °C for 12 h to obtain a chiral photocathode catalyst.

[0064] Example 4: This example provides a method for preparing a chiral photocathode catalyst, including the following steps:

[0065] S1. Disperse Cd(NO3)2·4H2O in deionized water to prepare 10 mL of 0.1 mol Cd(NO3)2 aqueous solution, denoted as solution A;

[0066] S2. Disperse L-cysteine ​​in a certain concentration of NaOH aqueous solution to prepare 10 mL of L-cysteine ​​aqueous solution with pH=8.0 and a concentration of 0.1 mol, to obtain solution B;

[0067] S3. Mix the above solutions A and B in 100 mL of aqueous solution and carry out a self-assembly reaction at 25 °C and 300 rpm under magnetic stirring for 12 h to obtain a turbid solution. Cool the turbid solution to room temperature and centrifuge at 8000 rad / min for 10 min to remove the supernatant and obtain a white solid product. Then wash the solid product with deionized water and ethanol by centrifugation several times and place the solid product in a vacuum drying oven to dry at 80 °C for 12 h to obtain a chiral photocathode catalyst.

[0068] Example 5: This example provides a method for preparing a chiral photocathode catalyst, including the following steps:

[0069] S1. Disperse Cd(CH3COO)2·2H2O in deionized water to prepare 10 mL of 0.1 mol Cd(CH3COO)2 aqueous solution, denoted as solution A;

[0070] S2. Disperse L-cysteine ​​in a certain concentration of NaOH aqueous solution to prepare 10 mL of L-cysteine ​​aqueous solution with pH = 10 and a concentration of 0.2 mol, to obtain solution B;

[0071] S3. Mix the above solutions A and B in 100 mL of aqueous solution and carry out a self-assembly reaction at 45 °C and 500 rpm with magnetic stirring for 4 h to obtain a turbid solution. Cool the turbid solution to room temperature and centrifuge at 8000 rad / min for 10 min to remove the supernatant and obtain a white solid product. Then wash the solid product with deionized water and ethanol by centrifugation several times and place the solid product in a vacuum drying oven to dry at 80 °C for 12 h to obtain a chiral photocathode catalyst.

[0072] Comparative Example 1: This comparative example provides a method for preparing an LD-chiral photocathode catalyst, comprising the following steps:

[0073] S1. Disperse CdCl2 in deionized water to prepare 10 mL of 0.1 mol CdCl2 aqueous solution, denoted as solution A;

[0074] S2. Disperse L-cysteine ​​in deionized water to prepare 5 mL of 0.1 mol L-cysteine ​​aqueous solution, and add 1 mL of 1 mol / L NaOH aqueous solution to adjust the pH value to obtain solution B;

[0075] S3. Disperse D-cysteine ​​in deionized water to prepare 5 mL of 0.1 mol D-cysteine ​​aqueous solution, and add 1 mL of 1 mol / L NaOH aqueous solution to adjust the pH value to obtain solution C;

[0076] S4. Mix solutions A, B, and C in 100 mL of aqueous solution and carry out a self-assembly reaction at 30 °C and 400 rpm with magnetic stirring for 6 h to obtain a turbid solution. Cool the turbid solution to room temperature and centrifuge at 8000 rad / min for 10 min to remove the supernatant and obtain a white solid product. Then wash the solid product with deionized water and ethanol by centrifugation several times and place the solid product in a vacuum drying oven to dry at 80 °C for 12 h to obtain the LD-ahidrotic photocathode catalyst, denoted as LD-CST.

[0077] I. Characterization of Surface Chemical Composition: Through observation Figure 1 The scanning electron microscope (SEM) images (a) of the L-type chiral photocathode catalyst and (b) of the D-type chiral photocathode catalyst clearly show that both exhibit left-handed and right-handed helical structures formed by the orderly stacking of sheet-like units. This unique helical morphology is a direct manifestation of the directional assembly of ligands induced by the chiral center. In the L-type chiral photocathode catalyst, chiral ligand molecules stack along a specific left-handed direction, transferring chiral characteristics from the molecular level to the macroscopic morphology through coordination bonds; similarly, the D-type chiral photocathode catalyst forms a right-handed helix, strongly demonstrating the successful preparation of L-type and D-type chiral photocathode catalysts at the microstructural level. Looking at Comparative Example 1 (c), the microstructure of the LD-type achiral photocathode catalyst is a sheet-like aggregated state. Comparing the helical structures of L- and D-type chiral photocathode catalysts reveals that LD-type achiral photocathode catalysts, lacking unidirectional chiral induction (or random mixing of chiral ligands), cannot form regular helices and can only accumulate into sheet-like structures. This indirectly verifies the crucial role of chiral induction in helical structure construction: the presence of a single chiral ligand (L or D) can drive the assembly system to form a helix along a specific direction; without a dominant single chirality (LD mixing), only a basic sheet-like structure can be formed. This indirectly corroborates the correlation between helical structure and chirality in L- and D-type chiral photocathode catalysts, thus completing the evidence chain for the preparation of chiral catalyst structures. The comparison between "single chirality → helical structure" and "random chirality → sheet-like structure" more rigorously demonstrates that chiral catalysts (L and D types) successfully construct helical morphologies through chiral induction, achieving controllable structural preparation.

[0078] analyze Figure 2 The X-ray diffraction (XRD) spectra of catalysts α show that the diffraction peak positions and intensities of the three catalysts (L-CST, D-CST, and LD-CST) are highly similar. XRD spectra reflect the crystal structure of materials, and the consistent peak shapes indicate that the three catalysts have similar crystal phase compositions and lattice parameters, i.e., they possess similar basic physicochemical structures. This provides a comparative premise of "same basic structure, different chiralities" for subsequent investigations into the influence of chirality on performance. Combined with... Figure 2 The X-ray photoelectron spectroscopy (XPS) data of b show that the binding energy of Cd in all three catalysts corresponds to the divalent state, indicating that Cd... 2+ It is the central ion. But a closer comparison... Figure 2 The binding energies of the Cd3d orbitals of b were examined, revealing a lower binding energy shift in the binding energies of D-CST and LD-CST compared to L-CST. According to the chemical shift principle of XPS binding energies, this decrease in binding energy implies an increase in the electron cloud density at the Cd center (i.e., a "richer" electron cloud), stemming from the binding energy of chiral ligands with Cd. 2+ During coordination, differences in chiral structure (levorotatory / dextrorotatory / random) lead to different electron donor effects of ligands on the Cd center: the levorotatory chiral ligands of L-CST react with Cd... 2+ During coordination, spatial configuration relatively "restricts" electron transfer; the right-handed ligand of D-CST, due to chiral induction, promotes the enrichment of more electrons towards the Cd center, while LD-CST, due to its random chirality, has an electron distribution between the two. This chiral-induced modulation of the electronic state of the Cd center is of great significance for optimizing the performance of lithium / aluminum-air batteries: differences in electron cloud density alter the Cd center's ability to capture and transport photogenerated carriers (electron-hole pairs), allowing electron-rich Cd centers to more efficiently capture photogenerated electrons and suppress electron-hole recombination; simultaneously, changes in electronic state affect the adsorption energy and migration path of ORR / OER reaction intermediates on the catalyst surface. Specifically, chiral modulation "differentiates" the electronic state of the Cd center, allowing for precise matching of the energy requirements for intermediate adsorption-desorption, accelerating reaction kinetics; carrier migration paths are also "smoother" due to optimized electronic states, reducing transport losses. Ultimately, the improved efficiency of photogenerated carrier utilization and the accelerated conversion of reaction intermediates jointly drive the overall performance advancement of lithium / aluminum-air batteries, including charge-discharge efficiency and cycle life. This reveals a new regulatory mechanism of "chiral structure-electronic state-performance" for the application of chiral photocatalysts in energy devices.

[0079] II. Characterization of chiral structure: by Figure 3The circular dichroism (CD) chromatograms show that the L-CST and D-CST prepared in Examples 1-2 of this invention are polarization-dependent on light. However, the LD-CST catalyst prepared in Comparative Example 1 is not polarization-dependent on light, indicating that the chiral structure catalyst has a unique selectivity to light.

[0080] III. Optical property characterization: analysis Figure 4 The UV-vis data show that the L-CST and D-CST prepared in Examples 1-2 of this invention exhibit a significant Cotton effect (circular dichroism signal peaks) in the characteristic wavelength range (such as the UV-Vis band), reflecting the difference in absorption of left-handed and right-handed circularly polarized light, i.e., exhibiting polarization-dependent characteristics. This stems from the helical structure of the chiral catalyst—the L-type left-handed helix and the D-type right-handed helix—which can interact with circularly polarized light of a specific direction through "chiral matching." This results in differentiated light absorption through electron transition coupling between light and the chiral framework, a direct manifestation of the chiral structure at the photophysical level. In contrast, the LD-CST catalyst prepared in Comparative Example 1 shows no significant Cotton effect in the characteristic band of its CD spectrum, and its absorption of left-handed and right-handed circularly polarized light is almost identical, exhibiting no polarization dependence. This is because the random mixing of chiral ligands in LD-CST (random stacking of L and D type ligands) disrupts the helical ordered structure induced by a single chirality, causing the overall chiral characteristics of the system to be "cancelled" and unable to interact specifically with circularly polarized light.

[0081] IV. Application Experiment: The L-CST and D-CST prepared in Examples 1-2 and the LD-CST prepared in Comparative Example 1 were dispersed in polypyrrolidone with the binder polyvinylidene fluoride at a mass ratio of 4:1. After being crushed, they were evenly sprayed on both sides of hydrophilic carbon paper and dried to obtain L-CST positive electrode, D-CST positive electrode and LD-CST positive electrode respectively.

[0082] Using the aforementioned L-CST, D-CST, and LD-CST positive electrode sheets as positive electrodes, lithium metal as the negative electrode, 1 mol / L LiTFSI / TEGDME liquid electrolyte as the electrolyte, and a glass fiber membrane as the separator, in a vacuum glove box, the lithium metal negative electrode was placed as the lower shell, and the glass fiber membrane and positive electrode were placed on top of it in sequence. Finally, 100 µL of electrolyte was added to fully wet the positive electrode and the glass fiber membrane. The top shell of the coin cell was then placed on top, and the battery was sealed using a tablet press to obtain a lithium-oxygen battery, which was denoted as L-type lithium-oxygen battery, D-type lithium-oxygen battery, and LD-type lithium-oxygen battery, respectively.

[0083] The charge-discharge performance of the lithium-oxygen battery was tested under the following conditions: current density 0.012 mA / cm². 2The cutoff voltage is 2 V to 4.5 V.

[0084] Depend on Figure 5 The charge-discharge curves of the lithium-oxygen battery in Figure a show that, under illumination, the charge-discharge overpotential of the battery system catalyzed by the L-type chiral photocathode catalyst is significantly lower than that under no-illumination conditions. This demonstrates that the chiral photocatalyst effectively accelerates the ORR / OER reaction kinetics of the cathode through photo-electric synergy. Further comparison reveals that the charge-discharge overpotential of the L-type chiral photocathode catalyst is approximately 0.75 V lower under illumination than under darkness. This indicates that the chiral framework has strong selective absorption of circularly polarized light and high efficiency in separating photogenerated electron-hole pairs, allowing it to participate effectively in ORR and OER, thereby minimizing overpotential loss. This result not only verifies the core role of chiral structures in photo-assisted catalysis, but also reveals the regulatory mechanism of battery performance through the "matching effect" of chiral configuration and illumination conditions. Single chirality, through precise synergy of light absorption, carrier transport, and reaction activation, demonstrates superiority over mixed chirality (LD type), providing a two-dimensional solution of "chiral configuration design + illumination regulation" for optimizing the energy conversion efficiency of lithium-oxygen batteries. Figure 5 From b, it was found that the L-type lithium-oxygen battery can also cycle stably for about 3000 hours under light conditions, proving that the chiral catalyst has excellent electrochemical performance.

[0085] V. Characterization of the growth behavior of discharge products in lithium-oxygen batteries: observation Figure 6 As shown in section a, taking the lithium-oxygen battery assembled with an L-type chiral photocathode catalyst as an example, under illumination, the discharge products exhibit a distorted flower-like morphology. This unique structure originates from the isochirality-induced effect of the L-type chiral photocathode catalyst. The chiral framework, through spatial configuration matching, drives the discharge products to grow directionally along a single chiral direction (i.e., "isochiral extension"): the flower-like structure is formed by the layer-by-layer curling and stacking of nanosheets, which not only has a larger specific surface area and exposes more active sites, but also constructs abundant pore channels through the gaps between the curls. These channels provide efficient pathways for the transport of lithium ions and oxygen molecules, reducing mass transfer resistance during the reaction process, thereby significantly improving the battery's discharge capacity. At the same time, the loose flower-like structure is more easily decomposed during charging, avoiding the coverage of dense products on the electrode surface and extending the battery's cycle life.

[0086] On the contrary Figure 6In the L-type chiral photocatalyst system under dark conditions (b), the discharge products exhibit a dense, plate-like structure. This is because, in the absence of light, the photogenerated carriers generated by the chiral catalyst are insufficient, the chiral induction effect is weakened, and the products cannot extend along a directional path, but can only accumulate disorderly to form plates. This dense, plate-like structure not only has a small specific surface area and low utilization of active sites, but also clogs electrode pores, hindering the transport of ions and oxygen, resulting in limited discharge capacity. Furthermore, it is difficult to completely decompose during charging, easily causing electrode passivation and further accelerating battery performance degradation.

[0087] The structural differences in the discharge products directly demonstrate the key value of the "light-chirality induction" synergistic effect. Light activation activates the photocatalytic performance of L-type chiral photocathode catalysts, enhances the directional regulation of product growth by same-chirality transfer, and achieves dual optimization of active site utilization and mass transfer efficiency through the construction of flower-like structures. This is the microstructural basis for the excellent performance of L-type chiral photocathode catalysts in lithium-oxygen batteries.

[0088] VI. General applicability of L-type chiral photocathode catalyst in other aluminum-air batteries: The L-CST prepared in Example 1 and the binder polytetrafluoroethylene were dispersed in ethanol at a mass ratio of 4:1. After pulverization, the mixture was uniformly sprayed onto both sides of hydrophilic carbon paper and dried to obtain an L-CST positive electrode sheet. Using the L-CST positive electrode sheet as the positive electrode and metallic aluminum as the negative electrode, an aluminum-air battery was assembled with a 4 mol / L KOH liquid electrolyte and a glass fiber separator, denoted as an L-type aluminum-air battery.

[0089] like Figure 7 As shown in figure a, the L-type aluminum-air battery system achieves a current density and power density of 71 mA / cm² under dark conditions. 2 With 39 mW / cm 2 Conversely, when under light conditions, such as Figure 7 As shown in b, the current density of the same battery system jumps dramatically to 180 mA / cm². 2 The power density has also been increased to 47 mW / cm². 2 This significant difference fully demonstrates that L-type chiral photocathode catalysts can effectively accelerate the electrode reaction kinetics of aluminum-air batteries through the synergistic effect of their unique chiral structure and photoresponse characteristics, significantly improving charge transfer efficiency and energy output capability. Further combining... Figure 8 As can be seen from the charge-discharge curve plateau of a, the L-type aluminum-air battery exhibits a lower overpotential under illumination, indicating a significantly reduced energy barrier for the electrode reaction and more efficient reaction; while Figure 8The test results for b further confirm that the system exhibits superior rate performance under illumination, maintaining stable output characteristics at different current densities, especially at high discharge rates. These experimental results collectively demonstrate the significant performance enhancement of the chiral photocatalyst on the overall performance of aluminum-air batteries under illumination. Through the synergistic regulation of photoexcitation and the chiral microenvironment, it provides a superior kinetic pathway for the battery reaction.

[0090] In summary, the chiral photocathode catalyst provided by the embodiments of the present invention and its application in metal gas batteries exhibit the following significant advantages in multiple dimensions:

[0091] 1. Existing techniques for preparing chiral catalysts, such as template methods and asymmetric synthesis, suffer from challenges including difficulty in precisely controlling the chiral structure, complex preparation processes, high costs, and poor stability in large-scale production. This invention employs a self-assembly method using Cd-based metal compounds and chiral organic ligands, resulting in a simpler and more efficient process. By precisely controlling the type of Cd salt, the type of chiral ligand, and their molar ratio, as well as optimizing reaction conditions such as temperature, pH, and reaction time, the precise construction of the chiral structure is achieved. Furthermore, this method eliminates the need for complex templates or stringent reaction conditions, effectively avoiding the defects of traditional methods such as easy collapse and racemization of the chiral structure. It also reduces production costs, improves production efficiency, and facilitates large-scale production.

[0092] 2. When conventional photocatalysts are applied to battery systems, they suffer from high electron-hole recombination rates and low light energy conversion efficiency. The chiral photocathode catalyst of this invention utilizes the unique optical and electrical properties of its chiral structure to efficiently separate photogenerated electron-hole pairs, significantly reducing the recombination rate. The chiral structure can selectively adsorb reactant molecules with specific configurations, particularly showing a significant promoting effect on the adsorption and activation of oxygen molecules and reaction intermediates, effectively accelerating the ORR and OER reactions. Using the chiral photocathode catalyst of this invention can improve the cathode reaction rate, greatly improve the reaction kinetics performance of lithium / aluminum-air batteries, and effectively enhance the battery's power output and charge / discharge efficiency.

[0093] 3. Addressing the issues of low energy conversion efficiency and poor stability in existing lithium / aluminum-air batteries, the solution provided in this invention exhibits superior optimization effects. By introducing a chiral photocatalyst, the power output of the aluminum-air battery is significantly improved, meeting the high-power demands of electric vehicles and other applications. In terms of charge-discharge performance, the battery's charge-discharge efficiency is significantly improved, and cycle life is extended. Simultaneously, the chiral photocatalyst can suppress the self-corrosion of the metal anode, reducing metal loss and lowering the risk of poisoning and deactivation of the air electrode catalyst. This significantly improves the overall stability and actual usable capacity of the battery, promoting the widespread application of lithium / aluminum-air batteries in electric vehicles, portable electronic devices, backup power supplies, and other fields.

[0094] 4. In this embodiment of the invention, a chiral photocathode catalyst is also applied to a lithium-oxygen battery, at 0.013 mA / cm². 2 The current density exhibits a discharge voltage of 3.16 V and a charging voltage of 3.30 V, with an energy conversion efficiency as high as 95.7%. Furthermore, the lithium-oxygen battery of this embodiment can stably cycle for over 3000 h under low polarization conditions; the aluminum-air battery of this embodiment achieves a rate performance of 4.2 mA / cm². 2 It still has a high discharge plateau at current densities.

[0095] 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 light-assisted metal-air battery, which is a lithium-air battery or an aluminum-air battery, comprising a negative electrode sheet, a separator, an electrolyte, and a positive electrode sheet, characterized by, The positive electrode tab is made of a chiral photoanode catalyst, which accelerates the positive electrode ORR / OER reaction kinetics through photo-electric synergistic effect under light conditions; the preparation method of the chiral photoanode catalyst comprises the following steps: Cd metal compound is dispersed in a first solvent to obtain solution A; the Cd metal compound is a divalent Cd salt; A chiral organic ligand is dispersed in an alkaline solution to obtain solution B; the chiral organic ligand is L-cysteine or D-cysteine; The alkaline solution is an alkaline water system with a pH value of 8.0-10.0; solution A and solution B are mixed for self-assembly reaction to obtain the chiral photoanode catalyst.

2. The light-assisted metal-air battery of claim 1, wherein, The Cd metal compound is one or more of cadmium chloride, cadmium nitrate and cadmium acetate.

3. The light-assisted metal-air battery of any one of claims 1-2, wherein, The molar ratio of the Cd metal compound to the chiral organic ligand is 1:(1-2).

4. The light-assisted metal-air battery of claim 1, wherein, The first solvent is deionized water.

5. The light-assisted metal-air battery of claim 1, wherein, The reaction temperature of the self-assembly reaction is 25-45℃.

6. The light-assisted metal-air battery of claim 1, wherein, The preparation method of the positive electrode tab comprises the following steps: The chiral photoanode catalyst is mixed with a binder and a second solvent to obtain a slurry; The slurry is coated on both sides of the current collector, followed by drying to obtain the positive electrode tab.

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