Battery positive electrode material, aqueous zinc ion battery and preparation method

Abstract

The invention belongs to the technical field of electrode active materials, and particularly relates to a battery positive electrode material, an aqueous zinc ion battery and a preparation method. Through in-situ uniform doping of the cobalt element, Co < 2 + > enters a MnCO3 crystal structure in a lattice site substitution manner, and the electron delocalization in a lattice can be enhanced by additional two valence electrons, so that an electron transition energy barrier is reduced by about 0.3 eV, and finally, the conductivity is improved by 1-2 orders of magnitude. The improvement of the conductivity directly accelerates the charge transfer rate of the electrode and the electrolyte interface, and effectively inhibits the polarization phenomenon under high current density. Besides, the doping of cobalt can reduce the dissolution trend of Mn < 2 + >, and the performance test shows that the capacity retention ratio of the material is almost 100% after 100 cycles at the medium-high current density of 1A g <-1 > under the preferable condition, and the capacity retention ratio still reaches 95.6% after 200 cycles.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrode active materials, and particularly relates to a cobalt-doped manganese carbonate positive electrode material. BACKGROUND

[0002] In recent years, the new energy industry has developed rapidly, and energy storage technology has become a core bottleneck restricting the large-scale application of renewable energy. Among various energy storage schemes, aqueous zinc-ion secondary batteries are recognized as one of the most potential substitutes for lithium-ion batteries due to the rich reserves of zinc resources, low redox potential of Zn 2+ / Zn electric pair, high theoretical capacity and intrinsic safety, and have shown broad application prospects in large-scale energy storage, portable electronic devices and other fields.

[0003] Although aqueous zinc-ion batteries have many advantages, their industrialization process still faces significant challenges. On the one hand, zinc negative electrode is prone to form dendrites during the cycle process, which increases the risk of battery short circuit, electrode side reactions and undesirable hydrogen evolution reactions, affecting the cycle life and safety; on the other hand, the existing positive electrode materials generally have the problems of fast capacity decay, poor conductivity, complex preparation process difficult to industrialization, etc., and the performance is difficult to meet the actual application requirements. The currently studied positive electrode materials mainly include vanadium-based compounds, prussian blue analogues, manganese-based oxides and organic polymers, etc. Among them, manganese dioxide has attracted widespread attention due to its high theoretical capacity, low raw material cost and environmental friendliness. However, its actual performance is limited by two key factors: first, poor cycle stability, intermediate phase MnOOH is easily generated during charging and discharging process in weak acid electrolyte, which is affected by Jahn-Teller effect and is prone to lattice distortion, structure collapse and dissolution in electrolyte, causing active material loss, and the capacity retention rate of most systems is only 50-70% after 100 cycles, and further decreases to 30-50% after 200 cycles; second, extremely low electronic conductivity (10 -8 ~ 10 -5 S / cm), which seriously limits the charge transfer efficiency and leads to poor rate performance.

[0004] To improve the overall performance of manganese-based cathode materials, elemental doping, especially cobalt doping, is widely adopted. By introducing cobalt ions to regulate the crystal and electronic structures of manganese oxides, the conductivity of the material can be effectively improved and the structural stability during charge and discharge processes can be enhanced. The preparation of this type of modified material mainly relies on hydrothermal reaction or precursor calcination process, achieving uniform cobalt doping in the crystal lattice through controllable synthesis. Typical products obtained after treatment include Co-Mn3O4 and Co-MnO2, both of which exhibit superior cycle durability compared to undoped materials, providing a feasible technical path for the design of high-performance aqueous zinc-ion battery cathode materials. For example, patent application number 202311032984.7 discloses a Co-MnO2 material prepared by precursor electrochemical oxidation. This patent first mixes manganese dioxide raw material with cobalt source to form a mixed solution with a specific concentration and ratio, obtains CoMn-LDH precursor through chemical coprecipitation, and then performs cyclic voltammetric scanning oxidation treatment on the precursor to obtain nano-flower-like cobalt-doped manganese dioxide nanomaterial Co. X MnO2 (x=0.01~0.4). Zinc-ion batteries constructed with this material exhibit good cycle stability and specific capacity at different current densities. However, the preparation of this patent requires the construction of a three-electrode system using an electrochemical workstation and precise control of cyclic voltammetry scanning parameters, which demands high equipment expertise and operational precision, and is susceptible to errors affecting product consistency. Patent application number 202410667627.6 discloses a cobalt-doped manganese oxide battery cathode material prepared by hydrothermal reaction. Using manganese acetate tetrahydrate, sodium bicarbonate, and potassium permanganate as basic raw materials, and cobalt nitrate hexahydrate as the cobalt source, a Co-Mn3O4 / MnOOH composite electrode material is finally prepared through a 180℃ hydrothermal reaction. This patent has a simple preparation process, and performance test data further verifies the effectiveness of this scheme: aqueous zinc-ion batteries prepared with this composite electrode material exhibit good cycle stability and specific capacity at 0.6Ag. -1 At current density, the cycle life can reach 800 cycles with a capacity retention of approximately 83%, significantly outperforming traditional pure manganese-based cathode materials. However, this material still has certain limitations: firstly, the product is a composite material of Co-Mn3O4 and MnOOH, in which MnOOH is not free from the Jahn-Teller effect, easily undergoing lattice distortion, structural collapse, and dissolution in the electrolyte during cycling, leading to the loss of active material; secondly, current performance tests are only based on 0.6Ag. -1 The low current density studies did not cover medium-to-high current scenarios, making it difficult to fully verify the material's performance in practical high-power applications, which to some extent limited the comprehensive evaluation of its overall performance. Furthermore, through patent literature and related technical data searches, the applicant found, as of the time of this application, no publicly available reports on the use of cobalt-doped manganese carbonate as a battery cathode active material, or on the preparation process related to the cobalt-doped manganese carbonate material described in this application. Summary of the Invention

[0005] The purpose of this application is to provide a novel battery cathode material. Under preferred conditions, zinc-ion batteries prepared using this cathode material exhibit good capacitance retention and specific capacity. This is achieved through the following technical solution:

[0006] A method for preparing a battery cathode material includes the following steps: dissolving a compound containing divalent cobalt ions, a compound containing divalent manganese ions, and a carboxyl-containing organic ligand in a solvent, and promoting the reaction of the three through a coordination complexation reaction to obtain a metal-organic ligand complex solution; the molar ratio of the carboxyl-containing organic ligand, divalent cobalt ions, and divalent manganese ions is 1:1:(1~3); adding an oxidant to the metal-organic ligand complex solution to carry out a hydrothermal reaction, promoting the decomposition of the ligand to generate carbonate ions, and simultaneously providing the oxidizing environment required for the reaction through the oxidant, promoting the simultaneous crystallization of divalent cobalt ions, divalent manganese ions, and carbonate ions to obtain Co-MnCO3; the molar ratio of the amount of oxidant added to divalent manganese ions is 1:(2~3).

[0007] Preferably, the molar ratio of the added oxidant to divalent manganese ions is 1:2.63.

[0008] Preferably, the carboxyl-containing organic ligand includes at least one of polycarboxylic acids, organic acid salts, and amino acids.

[0009] Preferably, the compound containing divalent cobalt ions includes at least one of cobalt chloride hexahydrate, cobalt nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt acetate tetrahydrate, and cobalt oxalate dihydrate.

[0010] Preferably, the compound containing divalent manganese ions includes at least one of manganese chloride tetrahydrate, manganese nitrate tetrahydrate, manganese sulfate monohydrate, manganese acetate tetrahydrate, and manganese oxalate dihydrate.

[0011] Preferably, the oxidant is potassium permanganate; and the carboxyl-containing organic ligand is citric acid.

[0012] Preferably, the hydrothermal reaction temperature is 150~180℃ and the time is 30~50min.

[0013] Preferably, the molar ratio of the carboxyl-containing organic ligand, divalent cobalt ions, divalent manganese ions, and oxidant is 33:33:50:19.

[0014] A battery cathode material is prepared using any of the preparation methods described above.

[0015] An aqueous zinc-ion battery, wherein the maximum specific capacity of the aqueous zinc-ion battery is 320.7 mAh g. -1 ; in 1Ag-1 The capacity retention rate is 95-96% after 200 cycles at current density.

[0016] Compared with the prior art, this application has the following beneficial effects:

[0017] Pure manganese carbonate due to Mn 2+ 3D 5 Its electronic configuration exhibits strong localization characteristics, with an electronic conductivity of only 10. -9 ~10 - 7 Scm -1 This severely restricts electrode reaction kinetics. This application addresses this issue by using in-situ uniform doping of cobalt. 2+ (3d) 7 The configuration (often referred to as "configuration") enters the MnCO3 crystal structure through lattice site substitution. Its two additional valence electrons enhance electron delocalization within the lattice, lowering the electron transition energy barrier by approximately 0.3 eV, ultimately achieving a 1-2 order of magnitude increase in conductivity (up to 10 eV after optimization). -6 ~10 -5 S / cm). This improvement in conductivity directly accelerates the charge transfer rate at the electrode-electrolyte interface, effectively suppressing polarization at high current densities. Furthermore, Co... 2+ With CO3 2- The binding energy (5.2 eV) is higher than that of Mn. 2+ (4.6 eV), its embedding can strengthen the bonding force of the lattice framework and suppress the degradation of Zn during charging and discharging. 2+ / H + Intercalation and extraction lead to lattice expansion and contraction. Simultaneously, cobalt doping can reduce Mn... 2+ To minimize the leaching trend and prevent the loss of active substances, performance tests show that under optimal conditions, the material exhibits a leaching rate of 1 Ag. -1 After 100 cycles at medium to high current densities, the capacity retention rate is nearly 100%, and after 200 cycles, it still reaches 95.6%, which is much higher than that of pure manganese dioxide (30%~50% retention rate after 200 cycles).

[0018] The coral-like hierarchical structure of the cathode material in this application (approximately 5-10 μm in diameter, with a porous network formed by nanosheets assembled on the surface) provides abundant channels for ion diffusion, enabling Zn... 2+ The diffusion coefficient reaches 1.2 × 10⁻⁶. -8 cm 2 / s, an order of magnitude improvement over the block structure. Meanwhile, Co 2+ The introduction of Zn through the modulation effect of the lattice electric field makes Zn 2+The diffusion activation energy decreased from 0.6 eV to 0.4 eV. This synergistic effect of "electron-ion dual conductivity" ensures that the material maintains excellent rate performance even at high capacity. Performance tests show that at 1 Ag... -1 At current density, the initial discharge specific capacity of the material can reach 320.7 mAh g. -1 It far exceeds that of pure manganese dioxide (200~280 mAh g). -1 ) and most of the reported manganese-based cathode materials.

[0019] The preparation method of this application adjusts the hydrothermal reaction parameters to make Mn 2+ Co 2+ With CO3 2+ Simultaneous crystallization within the reaction system reduces the total preparation time to one-third or even less of traditional hydrothermal processes. This "one-step" strategy avoids the separation and purification steps of intermediate products, significantly improving atom economy and aligning with the development concept of green chemistry. Compared to high-temperature solid-state methods (which typically require calcination above 800℃), this process lowers the hydrothermal temperature by over 640℃ and reduces energy consumption by over 60%. Furthermore, the raw materials used (manganese sulfate, cobalt sulfate, citric acid, etc.) are all industrial-grade conventional chemicals, inexpensive and readily available, significantly reducing material production costs. Attached Figure Description

[0020] The attached diagram will be briefly described below:

[0021] Figure 1 Figures 1-2 are SEM images of COMNO- (15%, 20%, 25%, 30%, 35%); Figures (a)-(d) are SEM images of COMNO- (15%, 20%, 25%, 35%) respectively; Figures (e)-(i) are SEM images of different selected areas of COMNO-30%.

[0022] Figure 2 Mapping images of different selection areas for COMNO-30%;

[0023] Figure 3 Images showing XRD test results for COMNO-(15%, 20%, 25%, 30%, 35%); PDF#00-007-0268 is a standard MnCO3 card;

[0024] Figure 4 Cyclic voltammetry curves of COMNO-30%│GF / A│Zn cells in the voltage range of 0.8~2.0V, at a scan rate of 0.2mV / s and a temperature of 30℃;

[0025] Figure 5For COMNO-30%│GF / A│Zn, COMNO-20%│GF / A│Zn, COMNO-15%│GF / A│Zn, and γ-MnO2│GF / A│Zn cells at 1Ag -1 Comparison of cycling stability under current density. Detailed Implementation

[0026] The present application will now be further described by way of specific embodiments. Those skilled in the art will be able to implement the present application based on these descriptions. Furthermore, the embodiments of the present application described below are generally only a part of the embodiments of the present application, and not all of the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort should fall within the scope of protection of the present application.

[0027] Example 1

[0028] A method for preparing a battery cathode material includes the following steps:

[0029] Preparation of solution A: Weigh 19 mmol of potassium permanganate into a 50 ml beaker and add 25 ml of deionized water.

[0030] Preparation of solution B: Weigh 16.5 mmol of cobalt chloride hexahydrate, 16.5 mmol of citric acid, and 50 mmol of manganese chloride tetrahydrate into a 50 ml beaker, add 10 ml of deionized water, and stir to dissolve.

[0031] Take 100ml of polytetrafluoroethylene reactor liner, first pour solution B into the reactor, then slowly pour solution A into the reactor and stir. At this time, take 5ml of deionized water to rinse the residual potassium permanganate solution in the beaker of solution A and pour it into the reactor (reactor filling degree 40%). Close the reactor liner, install the stainless steel reactor bushing, and place it in a forced-air drying oven at room temperature. Raise the temperature from room temperature to 160℃ and maintain it for 40 minutes. Start cooling with the oven. After the temperature drops to room temperature, open the reactor and perform centrifugation and cleaning operations. After cleaning with deionized water 4 times, clean with anhydrous ethanol 2 times and put it into an oven at 60 degrees for 12 hours to dry. The battery positive electrode material Co-MnCO3 (denoted as COMNO-15%) is obtained.

[0032] This embodiment also discloses a zinc-ion battery prepared using the above-mentioned positive electrode material. The preparation process of the zinc-ion battery is as follows: Co-MnCO3 active material, acetylene black, and binder (PVDF) are uniformly mixed in N-methylpyrrolidone (NMP) at an optimal weight ratio of 7:2:1. Using a 120 μm thick doctor blade, the mixture is uniformly coated onto a 0.01 mm thick titanium foil current collector. Finally, it is dried in a vacuum drying oven at 60°C for 12 hours. The film is then punched using a 12 mm diameter punching machine and placed in a desiccator for later use. The active material loading is controlled at 1.3 ± 0.3 mg / cm³. -1 Within the specified range, a positive electrode sheet is obtained. The positive electrode shell, positive electrode sheet, GF / A separator, zinc sheet, stainless steel spring sheet, gasket, and negative electrode shell are assembled sequentially into a button cell. The assembly is performed under a nominal pressure of 50 kPa to obtain a zinc-ion battery (denoted as COMNO-15%│GF / A│Zn).

[0033] Example 2

[0034] The difference between the preparation method of the battery cathode material in this embodiment and that in Example 1 is that the amount of cobalt chloride hexahydrate and citric acid added during the preparation of solution B is 22 mmol. The final battery cathode material obtained is Co-MnCO3 (denoted as COMNO-20%). In addition, this embodiment also prepared a zinc-ion battery (denoted as COMNO-20%│GF / A│Zn) using the above-mentioned battery cathode material, and the preparation process is the same as in Example 1.

[0035] Example 3

[0036] The difference between the preparation method of the battery cathode material in this embodiment and that in Example 1 is that the amount of cobalt chloride hexahydrate and citric acid added during the preparation of solution B is 27.5 mmol. The final battery cathode material obtained is Co-MnCO3 (denoted as COMNO-25%). In addition, this embodiment also prepared a zinc-ion battery (denoted as COMNO-25%│GF / A│Zn) using the above-mentioned battery cathode material, and the preparation process is the same as in Example 1.

[0037] Example 4

[0038] The difference between the preparation method of the battery cathode material in this embodiment and that in Example 1 is that, during the preparation of solution B, the amount of cobalt chloride hexahydrate added is 33 mmol, and the amount of citric acid added is 33 mmol. The final battery cathode material obtained is Co-MnCO3 (denoted as COMNO-30%). In addition, this embodiment also prepared a zinc-ion battery (denoted as COMNO-30%│GF / A│Zn) using the above-mentioned battery cathode material, and the preparation process is the same as in Example 1.

[0039] Example 5

[0040] The difference between the preparation method of the battery cathode material in this embodiment and that in Example 1 is that the amount of cobalt chloride hexahydrate and citric acid added during the preparation of solution B is 38.5 mmol. The final battery cathode material obtained is Co-MnCO3 (denoted as COMNO-35%). In addition, this embodiment also prepared a zinc-ion battery (denoted as COMNO-35%│GF / A│Zn) using the above-mentioned battery cathode material, and the preparation process is the same as in Example 1.

[0041] Comparative Example 1

[0042] The positive electrode material of this comparative example is γ-MnO2, and the preparation steps are the same as in Example 1. However, in the preparation of solution A, the amount of potassium permanganate added is 30 mmol, and in the preparation of solution B, cobalt chloride hexahydrate and citric acid are not added, and the amount of manganese chloride tetrahydrate added is 40 mmol. In addition, this example also prepared a zinc-ion battery (denoted as γ-MnO2│GF / A│Zn) using the above-mentioned positive electrode material, and the preparation process is the same as in Example 1.

[0043] Comparative Example 2

[0044] The difference between the positive electrode material of this comparative example and that of Example 4 is the absence of citric acid. Furthermore, this comparative example also prepared a zinc-ion battery (denoted as C-MNO-15%│GF / A│Zn) using the aforementioned positive electrode material; the preparation process is described in Example 1.

[0045] Comparative Example 3

[0046] The difference between the positive electrode material of this comparative example and that of Example 4 is that citric acid is replaced with acetic acid. Furthermore, this comparative example also prepared a zinc-ion battery (denoted as C-COMNO-15%│GF / A│Zn) using the above-mentioned positive electrode material; the preparation process is described in Example 1.

[0047] Performance Test 1

[0048] This performance test used a scanning electron microscope (SEM, SU8100, HITACHI Corporation, Japan) to physically characterize the battery cathode materials prepared in the examples and comparative examples. Please refer to [link to relevant documentation]. Figure 1 From the overall morphology, all cobalt-doped samples exhibited a hierarchical structure, but the doping amount significantly affected the morphological regularity: COMNO-15% (low doping) and COMNO-35% (high doping) samples showed severe local agglomeration and small or large and non-uniform particle sizes, and the porous network structure assembled from nanosheets was relatively loose. Figure 1a, d); The coral spherical structure of the COMNO-20% and COMNO-25% samples is beginning to take shape, but they are not spheres of uniform size, and the surface nanosheets are arranged in a disordered manner with uneven pore size distribution. Figure 1 b, c). In contrast, the COMNO-30% sample exhibits the most regular coral spherical hierarchical structure: the spheres are approximately 3-5 μm in diameter, and their surfaces are composed of a continuous porous network formed by the interlacing of nanosheets. Figure 1 (e~i), with pore sizes concentrated in the 200~500 nm range. This structure not only provides a large specific surface area but also facilitates electrolyte permeation and Zn... 2+ Diffusion creates abundant channels, which is an important structural basis for high-capacity characteristics.

[0049] Please see Figure 2 The elemental distribution results show that Co, Mn, and O exhibit a uniform co-distribution throughout the coral spheroid structure, but vary in different selected areas. Figure 2 In A and B), the signal intensity of Co changes synchronously with that of Mn, and there are no obvious enrichment or deficiency regions. Figure 2 The elemental distribution inside the C sphere remains uniform, indicating that Co 2+ Instead of forming independent phases or local agglomerations, Co is uniformly embedded in the MnCO3 crystal via lattice substitution. This result directly verifies the successful achievement of "in-situ uniform doping of Co": Co 2+ With Mn 2+ Simultaneous crystallization occurs during hydrothermal synthesis, occupying Mn 2+ The lattice sites provide microscopic evidence for improved electronic delocalization (enhanced conductivity) and enhanced lattice bonding (enhanced structural stability).

[0050] Performance Test 2

[0051] This performance test performed XRD tests on the battery cathode materials prepared in the examples and comparative examples. Please refer to [link to relevant documentation]. Figure 3 The diffraction peak positions of the COMNO series samples (15%~35%) all closely match those of the standard cards. The main characteristic peaks (2θ=24.299°, 31.475°, 37.604°, 41.544°, 45.306°) correspond to the (012), (104), (110), (113), and (202) crystal planes of MnCO3, respectively. No diffraction peaks of impurity phases such as CoO and Co3O4 were observed, indicating that Co... 2+ The doping did not disrupt the hexagonal crystal structure of MnCO3. With increasing Co doping concentration, the characteristic peaks shifted slightly towards higher angles (approximately 0.2°–0.3°), which is due to the presence of Co. 2+ The ionic radius (0.74 Å) is smaller than that of Mn. 2+(0.83 Å), due to the slight contraction of the lattice constant after substitution, further proves that Co 2+ It successfully entered the MnCO3 lattice, consistent with the structural mechanism of "in-situ doping".

[0052] Performance Test 3

[0053] This performance test was conducted on the COMNO-30%│GF / A│Zn battery prepared in Example 4. Three-cycle cyclic voltammetry (CV) curves were measured under the conditions of a voltage range of 0.8–2.0 V, a scan rate of 0.2 mV / s, and a temperature of 30 °C. Please refer to [link to relevant documentation]. Figure 4 It can be observed that under near-steady-state conditions (scan rate of 0.2 mV / s), a distinct redox peak appears in the curve: the oxidation peak appears at 1.6248 V, corresponding to a peak current of 1.1619 mA, reflecting the Zn... 2+ / H + The oxidation process from the MnCO3 lattice should have two oxidation peaks, but they overlapped because their oxidation potentials were too close. The large full width at half maximum (FWHM) of the oxidation peak confirms this overlap. There are two reduction peaks, located at 1.3598 V (corresponding to a peak current of -918.56 μA) and 1.1772 V (corresponding to a peak current of -259.62 μA), corresponding to Zn... 2+ The reduction process of / H⁺ intercalation into the MnCO3 lattice is consistent with the typical ion intercalation / deintercalation behavior of aqueous zinc-ion battery cathode materials.

[0054] Quantitative analysis showed that the oxidation peak area was 893.76 mC, and the reduction peak (the sum of the two reduction peaks) was 856.06 mC. The ratio of the two was approximately 1.04, close to 1, indicating that the charge transfer of the electrode reaction was highly reversible. This was attributed to the enhanced lattice stability of the in-situ uniform cobalt doping and the stable and rapid reaction interface and channels provided by the coral spherical structure, which effectively suppressed the loss of active material, structural collapse, and expansion during the charge and discharge process. This provided direct electrochemical evidence for the material's high capacity retention at high current densities during cyclic testing.

[0055] Performance Test 4

[0056] This performance test compares the cycling performance of batteries prepared in Examples 1, 2, and 4 with those in Comparative Examples 1-3 at a current density of 1 A / g under medium to high current. The results are shown in the table below:

[0057] Table 1 Comparison of Cyclic Performance

[0058]

[0059] In terms of capacity and retention: COMNO-30% performed best, with nearly 100% capacity retention after 100 cycles and still reaching 95.6% after 200 cycles, with a maximum capacity of 320.7 mAhg. -1 The capacity retention rates of COMNO-20% and COMNO-15% after 200 cycles were 55.63% and 38.91%, respectively; while the capacity of γ-MnO2 decayed to 39.2% of its initial value after 100 cycles, and only 33.75% after 200 cycles. The difference in capacity decay can be attributed to: ① The uniform cobalt doping of COMNO-30% enhances lattice stability (suppressing volume expansion and Mn during charging and discharging). 2+ (1) Dissolution); 2) The coral-like spherical structure provides a stable and rapid reaction interface and channel; 3) Improved conductivity reduces electrode polarization loss. This result directly verifies the advantages of "cobalt doping synergistically optimizing structural stability and kinetic performance", highlighting the industrialization potential of COMNO-30% as a cathode material. In addition, citric acid plays an irreplaceable key role in the preparation of cathode materials. First, comparative experiments show that the cycle performance of Comparative Example 2 without added citric acid is only about 1 / 3 of that of Example 4, fully demonstrating its necessity for the cycle stability of the material; second, although Comparative Example 3 introduced the organic ligand acetic acid, its performance only reached half of that of Example 4, indicating that the function of citric acid cannot be replaced by ordinary organic acids. Further analysis revealed that the morphology of the product obtained from the acetic acid system is completely different from that of the product in the examples. Unlike the starchy morphology of manganese carbonate, it exists mostly in a particulate state, which was confirmed to be not the target manganese carbonate material, indicating that the reaction path and product have been shifted. It can be seen that citric acid not only regulates crystal growth and optimizes material morphology through coordination, but also directly affects the selectivity of the reaction and the composition of the product. This also explains, from the perspective of the material's inherent properties, why the electrochemical performance of Comparative Example 3 is far inferior to that of Example 4.

Claims

1. A method for preparing a battery cathode material, characterized in that, Includes the following steps: A compound containing divalent cobalt ions, a compound containing divalent manganese ions, and a carboxyl-containing organic ligand are dissolved in a solvent. A coordination complexation reaction is then initiated to produce a metal-organic ligand complex solution. The molar ratio of the carboxyl-containing organic ligand, divalent cobalt ions, and divalent manganese ions is 1:1:(1~3). An oxidant is added to the metal-organic ligand complex solution, and a hydrothermal reaction is initiated to decompose the ligand and generate carbonate ions. Simultaneously, the oxidant provides the necessary oxidative environment for the reaction, promoting the simultaneous crystallization of divalent cobalt ions, divalent manganese ions, and carbonate ions to obtain Co-MnCO3. The molar ratio of the oxidant added to divalent manganese ions is 1:(2~3).

2. The method for preparing a battery cathode material according to claim 1, characterized in that, The carboxyl-containing organic ligands include at least one of polycarboxylic acids, organic acid salts, and amino acids.

3. The method for preparing a battery cathode material according to claim 1, characterized in that, The compounds containing divalent cobalt ions include at least one of cobalt chloride hexahydrate, cobalt nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt acetate tetrahydrate, and cobalt oxalate dihydrate.

4. The method for preparing a battery cathode material according to claim 1, characterized in that, The compound containing divalent manganese ions includes at least one of manganese chloride tetrahydrate, manganese nitrate tetrahydrate, manganese sulfate monohydrate, manganese acetate tetrahydrate, and manganese oxalate dihydrate.

5. The method for preparing a battery positive electrode material according to claim 1, characterized in that, The oxidant is potassium permanganate; the carboxyl-containing organic ligand is citric acid.

6. The method for preparing a battery cathode material according to claim 1, characterized in that, The hydrothermal reaction temperature is 150~180℃, and the time is 30~50min.

7. The method for preparing a battery cathode material according to claim 1, characterized in that, The molar ratio of the carboxyl-containing organic ligand, divalent cobalt ions, divalent manganese ions, and oxidant is 33:33:50:

19.

8. A battery positive electrode material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. An aqueous zinc-ion battery, characterized in that, The battery cathode material described in claim 8 is used.

10. An aqueous zinc-ion battery according to claim 9, characterized in that, The maximum specific capacity of the aqueous zinc-ion battery is 320.7 mAh g. -1 ; in 1A g -1 The capacity retention rate is 95-96% after 200 cycles at current density.

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