Mo2C-Na2Mn8O16 composite material with synergistic lattice strain and preparation method of Mo2C-Na2Mn8O16 composite material

Abstract

The invention provides a Mo2C-Na2Mn8O16 composite material with synergistic lattice strain and a preparation method of the Mo2C-Na2Mn8O16 composite material, and belongs to the field of inorganic materials. The preparation method comprises the following steps: dissolving a sodium molybdate dehydrate solid, a manganous nitrate aqueous solution, a potassium permanganate solid and an ammonium bicarbonate solid in deionized water, and carrying out hydrothermal reaction, filtration, drying and calcination treatment to obtain a target material. The composite material has the morphology that micron-sized cubes and nano-particles coexist, the structural stability of the material is remarkably enhanced by means of synergistic lattice strain caused by two-phase compounding of Mo2C and Na2Mn8O16, and then the electrochemical performance of the composite material in the zinc ion battery is effectively improved. The preparation method is simple in process and easy to implement, and the obtained composite material shows good stability as an aqueous zinc ion battery positive electrode material and has a wide application prospect.

Description

Technical Field

[0001] This invention discloses a synergistic lattice strain Mo2C-Na2Mn8O 16 The composite material and its preparation method belong to the field of aqueous zinc-ion battery technology in inorganic materials. Background Technology

[0002] With the global energy structure transitioning towards renewable energy, the development of safe, low-cost, and environmentally friendly large-scale energy storage technologies has become an urgent need. Among numerous candidate technologies, aqueous zinc-ion batteries show great promise due to their safety, environmental friendliness, and high theoretical capacity. However, their development is constrained by the performance limitations of cathode materials. Among various cathode materials, sodium manganese oxide has attracted much attention due to its unique structure. This material possesses two-dimensional diffusion channels suitable for zinc ion insertion and extraction, has a high theoretical capacity, and is rich in manganese and environmentally friendly. However, its poor intrinsic conductivity and susceptibility to manganese dissolution and structural collapse during cycling severely limit its practical applications.

[0003] Molybdenum carbide (Mo2C), as a typical transition metal carbide, exhibits unique advantages in electrochemical energy storage due to its high conductivity and excellent chemical stability. However, a key challenge in the practical application of Mo2C lies in the tendency of its high surface energy nanoparticles to aggregate during synthesis. This leads to the carbon layer covering the active molybdenum sites, increasing interparticle resistance, reducing the available active sites, resulting in low charge transport efficiency and severely deteriorating electrode reaction kinetics. Currently, strategies such as nanostructure engineering and high specific surface area carrier composites can prevent nanoparticle aggregation and promote charge transfer. Biomass-based materials also facilitate the dispersion of molybdenum salt precursors, thereby improving the distribution of Mo2C. However, existing biomass-derived catalysts often rely on exogenous additives to enhance Mo2C dispersion, which not only complicates the synthesis process but may also compromise the integrity of the material. The application of Mo2C in aqueous zinc-ion battery cathode materials, especially its composite with manganese-based oxides, remains in the exploratory stage. Summary of the Invention

[0004] To overcome the technical shortcomings of sodium manganese oxide in zinc-ion battery applications, this invention provides a synergistically strained Mo2C-Na2Mn8O 16 Composite materials and their preparation methods belong to the field of inorganic materials. Sodium molybdate dihydrate solid, manganese nitrate aqueous solution, potassium permanganate solid, and ammonium bicarbonate solid are dissolved in deionized water. Following hydrothermal reaction, filtration, drying, and calcination, a Mo2C-Na2Mn8O composite with a co-strained lattice structure is obtained. 16 Composite materials. This invention utilizes Mo2C and Na2Mn8O 16The synergistic lattice strain induced by the two-phase composite significantly enhances the structural stability of the material, thereby effectively improving its electrochemical performance in zinc-ion batteries. Microstructural characterization reveals that the composite material exhibits a hybrid morphology of micron-sized cubic particles and nanoparticles, further promoting charge transport and interfacial reactions. This method is simple, uses low-cost raw materials, and is easy to scale up, demonstrating promising prospects for industrial applications.

[0005] The synergistic lattice strain Mo2C-Na2Mn8O of the present invention 16 The composite material exhibits characteristic diffraction peaks at 2θ angles of 36.6°, 41.5°, and 53.5° in its XRD pattern; and characteristic peaks at binding energies of 231.59 eV, 234.75 eV, 284.06 eV, 529.23 eV, 530.79 eV, 641.78 eV, 653.31 eV, and 1071.2 eV in its XPS spectrum; and the Mn exhibits both +3 and +4 valences.

[0006] This invention also provides Mo2C-Na2Mn8O with synergistic lattice strain. 16 The method for preparing composite materials includes the following steps:

[0007] The first step is to disperse sodium molybdate dihydrate solid in deionized water, and then add manganese nitrate aqueous solution, potassium permanganate solid and ammonium bicarbonate solid in sequence, and stir until they are mixed evenly.

[0008] The second step is to transfer the resulting mixed solution to a hydrothermal reactor, place it in an oven for constant temperature reaction, and allow it to cool naturally to room temperature after the reaction is complete.

[0009] The third step is to remove the reaction product, wash and filter it, and then dry it in an oven.

[0010] The fourth step involves calcining the dried product in a muffle furnace under air atmosphere, followed by cooling to obtain the concordantly strained Mo2C-Na2Mn8O. 16 Composite materials.

[0011] Furthermore, in the above technical solution, in the first step, the molar ratio of sodium molybdate dihydrate to potassium permanganate is 1:3.

[0012] Furthermore, in the above technical solution, in the first step, the molar ratio of potassium permanganate to manganese nitrate and ammonium bicarbonate is 3:20:48.

[0013] Furthermore, in the above technical solution, in the second step, the temperature of the isothermal reaction is 160℃, and the reaction time is 6 hours.

[0014] Furthermore, in the above technical solution, in the third step, the reaction product is washed with pure water. Specifically, the product is placed in pure water to form a suspension, ultrasonically treated for 5 minutes, and then filtered. This washing process is repeated a total of 5 times.

[0015] Furthermore, in the above technical solution, in the third step, the drying temperature is 80℃ and the drying time is 1 hour.

[0016] Furthermore, in the above technical solution, in the fourth step, the calcination temperature is 450℃ and the constant temperature calcination time is 5 hours; wherein, the time to heat up to 450℃ is 2 hours, and the time to naturally cool down to below 200℃ after calcination is 2 hours.

[0017] The present invention also provides the above-mentioned synergistic lattice strained Mo2C-Na2Mn8O 16 Application of composite materials in the cathode of aqueous zinc-ion batteries.

[0018] Beneficial effects of the invention

[0019] 1. This invention successfully prepared Mo2C-Na2Mn8O with synergistic lattice strain effect. 16 Composite materials. The raw materials used are low-cost and widely available, the synthesis process is simple, the entire preparation process is environmentally friendly, with low pollutant emissions, and it is easy to achieve large-scale production.

[0020] 2. This method constructs a composite morphology combining micron-sized cubes and nanoparticles through a hydrothermal reaction. This is achieved using Mo₂C and Na₂Mn₈O₃. 16 The synergistic lattice strain induced by the two-phase composite significantly enhances the structural stability of the material, thereby effectively improving its electrochemical performance in zinc-ion batteries.

[0021] 3. The process of this invention is simple and has good repeatability. The resulting composite material shows good application potential and industrialization prospects in the field of zinc-ion battery cathode materials. Attached Figure Description

[0022] Figure 1 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 1 16 XRD pattern of the composite material;

[0023] Figure 2 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 1 16 SEM images of the composite materials; where: (a) is the SEM image of cubic particles; (b) is the SEM image of nanoparticles;

[0024] Figure 3 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 116 XPS spectra of composite materials; where: (a) is the full XPS spectrum; (b) is the XPS spectrum of Mn2p; (c) is the XPS spectrum of O1s; (d) is the XPS spectrum of Mo3d; (e) is the XPS spectrum of C1s; (f) is the XPS spectrum of Na1s.

[0025] Figure 4 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 1 16 EDS diagram of the composite material;

[0026] Figure 5 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 1 16 Elemental distribution diagrams of composite materials; where: (a) is the elemental distribution diagram of Mn; (b) is the elemental distribution diagram of O; (c) is the elemental distribution diagram of Mo; (d) is the elemental distribution diagram of C; (e) is the elemental distribution diagram of C.

[0027] Figure 6 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 1 16 Infrared spectrum of the composite material;

[0028] Figure 7 The Mo2C-Na2Mn8O with synergistic lattice strain in Example 1 16 Raman spectrum of the composite material;

[0029] Figure 8 Mo2C-Na2Mn8O with synergistic lattice strain in Example 5 16 Cyclic charge-discharge diagram of composite materials;

[0030] Figure 9 Mo2C-Na2Mn8O with synergistic lattice strain in Example 5 16 Cyclic voltammetry of composite materials;

[0031] Figure 10 Mo2C-Na2Mn8O with synergistic lattice strain in Example 5 16 AC impedance diagram of composite materials. Detailed Implementation

[0032] The present invention is further described below through specific examples. However, these examples are merely exemplary and are not limited to the scope of protection of the present invention; they are merely embodiments.

[0033] In the following embodiments, unless otherwise specified, the reagents, materials and instruments used are all conventional reagents, materials and instruments, and are commercially available. The reagents involved can also be synthesized by conventional synthesis methods.

[0034] Example 1

[0035] The first step is to disperse 0.2420g of sodium molybdate dihydrate and 7.158g of 50% manganese nitrate aqueous solution in 60mL of deionized water and stir for 1 hour.

[0036] The second step involves adding 0.4741g of potassium permanganate and 3.7949g of ammonium bicarbonate to the above solution and stirring for another hour.

[0037] The third step is to transfer the resulting mixed solution to a hydrothermal reactor, place it in an oven, and react it at a constant temperature of 160°C for 6 hours, and then allow it to cool naturally to room temperature.

[0038] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. The reaction product is placed in pure water to form a suspension, and then ultrasonicated in an ultrasonic cleaner for 5 minutes. The suspension is then filtered, and the process is repeated a total of 5 times.

[0039] Fifth step: Place the cleaned filtered product into an oven and dry at 80°C for 1 hour.

[0040] The sixth step involves calcining the dried product in a muffle furnace. After calcination, cooling yields the co-strained Mo2C-Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0041] Figure 1 Mo2C-Na2Mn8O exhibits synergistic lattice strain 16 XRD pattern of the composite material. The composite material consists of hexagonal Mo2C (PDF#01-081-8931) and tetragonal Na2Mn8O. 16 (PDF#00-029-1244) The composite material consists of two phases with mass fractions of 53.8% and 46.2%, respectively. All diffraction peaks were accurately identified, and no impurity phase peaks were present, indicating that a high-purity composite material was successfully obtained. The peak at 36.6° corresponds to the (101) crystal plane of Mo2C, and the peak at 41.5° corresponds to Na2Mn8O. 16 The peak at (301) crystal plane corresponds to the (110) crystal plane of Mo2C at 53.5°. For the Mo2C phase, the cell parameters exhibit a significant expansion of approximately 4.34% along the c-axis. Meanwhile, Na2Mn8O... 16 The cell parameters of the phase exhibit expansion of approximately 1.01% and 1.80% along the a / b and c-axis directions, respectively. The significant expansion along the c-axis suggests that Mn... 3+The content increased. During the formation of the composite material, electron transfer may have occurred in the precursor, leading to the partial increase of Mn content. 4+ Restored to Mn 3+ .

[0042] Figure 2 Mo2C-Na2Mn8O with coordinated lattice strain 16 The SEM image of the composite material clearly shows that it is mainly composed of nanoparticles and micron-sized cubic structures. The cubic structures exhibit obvious cracks on their surfaces, displaying a unique morphology assembled from smaller cubic units, with nanoscale particles attached to the outer surface of the cubes.

[0043] Figure 3 Mo2C-Na2Mn8O with coordinated lattice strain 16 XPS full spectrum of the composite material. (See full spectrum) Figure 3 As shown in (a), the material surface mainly contains Mn, O, Mo, C, and Na elements. Mn 2p spectrum Figure 3 In (b), Mn 2p 3 / 2 and Mn 2p 1 / 2 The binding energies are located at 641.78 eV and 653.31 eV, respectively, and the spin-orbit splitting value is 11.53 eV, indicating that Mn in Na2Mn8O 16 It exists in a mixed valence state. O 1s spectrum Figure 3 In (c), the main peak at 529.23 eV is attributed to lattice oxygens such as Mn–O and Na–O, while the peak at 530.79 eV originates from surface-adsorbed oxygen, hydroxyl groups, oxygen vacancies, and Mo–O species formed by the oxidation of Mo2C surface. This directly proves that Mo2C interacts with its surrounding environment or with Na2Mn8O. 16 There is an interaction at the interface; that is, there is an oxide layer on the Mo2C surface, which interacts with Na2Mn8O. 16 A tight interface is formed. Figure 3 In the Mo 3d spectrum of (d), Mo 3d 5 / 2 and Mo 3d 3 / 2 The values ​​at 231.59 eV and 234.75 eV, respectively, further confirm the presence of Mo. (From the C 1s spectrum...) Figure 3 (e) As can be seen in the figure, the signal at 284.06 eV can be attributed to the Mo–C bond. Na 1s spectrum Figure 3 (f) The peak at 1071.2 eV corresponds to the Na–O ionic bond, reflecting the Na… + The intercalation state within the Mn–O framework not only affects the crystal stability of the material but also plays a crucial role in regulating ion transport behavior.

[0044] Figure 4 Mo2C-Na2Mn8O with coordinated lattice strain 16 The EDS diagram of the composite material showed that five elements, Mn, O, Mo, Na and C, were detected in the analysis area. Mo, Mn and O had the highest signal intensities, indicating that they are the main constituent elements of the composite material.

[0045] Figure 5 Mo2C-Na2Mn8O with coordinated lattice strain 16 Elemental distribution diagram of the composite material. Mn, O, Mo, Na, and C all show clear and uniformly distributed signals, indicating that in this type of morphology, Mo2C-Na2Mn8O... 16 The two phases coexist stably in a composite form, and the uniform distribution of elements in the nanoparticle region further confirms the successful formation of the Mo2C phase.

[0046] Figure 6 Mo2C-Na2Mn8O with coordinated lattice strain 16 Infrared spectrum of the composite material. Located at 457.2 cm⁻¹. -1 The peak at 860.25 cm⁻¹ represents the Na–O stretching vibration. -1 Mn at the location 4+ –O stretching vibration and 1404.24 cm -1 The peaks at the flaking point originate from the absorption peaks of surface adsorbed species, which together confirm the coexistence of multiple valence states of manganese in the material.

[0047] Figure 7 Mo2C-Na2Mn8O with coordinated lattice strain 16 The Raman spectrum of the composite material is located at 634.64 cm⁻¹. -1 The peak at that location is Na2Mn8O 16 The phase exhibits Mn–O symmetric stretching vibrations, with increased bond strength due to lattice stress introduced by Mo2C; located at 280.53 cm⁻¹. -1 The Na–O lattice vibration peak at that location reflects the Na + The state of motion within the interlayer structure.

[0048] Example 2

[0049] The first step involves dispersing 0.7259 g of sodium molybdate dihydrate and 6.4422 g of 50% manganese nitrate aqueous solution in 60 mL of deionized water and stirring for 1 hour.

[0050] The second step involves adding 0.4741g of potassium permanganate and 3.7949g of ammonium bicarbonate to the above solution and stirring for another hour.

[0051] The third step is to transfer the resulting mixed solution to a hydrothermal reactor, place it in an oven, and react it at a constant temperature of 160 °C for 6 hours, and then allow it to cool naturally to room temperature.

[0052] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. The reaction product is placed in pure water to form a suspension, and then ultrasonicated in an ultrasonic cleaner for 5 minutes. The suspension is then filtered, and the process is repeated a total of 5 times.

[0053] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0054] The sixth step involves calcining the dried product in a muffle furnace. After calcination, cooling yields the co-strained Mo2C-Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0055] Example 3

[0056] The first step involves dispersing 1.4517 g of sodium molybdate dihydrate and 5.3685 g of 50% manganese nitrate aqueous solution in 60 mL of deionized water and stirring for 1 hour.

[0057] The second step involves adding 0.4741g of potassium permanganate and 3.7949g of ammonium bicarbonate to the above solution and stirring for another hour.

[0058] The third step is to transfer the resulting mixed solution to a hydrothermal reactor, place it in an oven, and react it at a constant temperature of 160 °C for 6 hours, and then allow it to cool naturally to room temperature.

[0059] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. The reaction product is placed in pure water to form a suspension, and then ultrasonicated in an ultrasonic cleaner for 5 minutes. The suspension is then filtered, and the process is repeated a total of 5 times.

[0060] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0061] The sixth step involves calcining the dried product in a muffle furnace. After calcination, cooling yields the co-strained Mo2C-Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0062] Example 4

[0063] The first step involves dispersing 2.1776 g of sodium molybdate dihydrate and 4.2948 g of 50% manganese nitrate aqueous solution in 60 mL of deionized water and stirring for 1 hour.

[0064] The second step involves adding 0.4741g of potassium permanganate and 3.7949g of ammonium bicarbonate to the above solution and stirring for another hour.

[0065] The third step is to transfer the resulting mixed solution to a hydrothermal reactor, place it in an oven, and react it at a constant temperature of 160 °C for 6 hours, and then allow it to cool naturally to room temperature.

[0066] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. The reaction product is placed in pure water to form a suspension, and then ultrasonicated in an ultrasonic cleaner for 5 minutes. The suspension is then filtered, and the process is repeated a total of 5 times.

[0067] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0068] The sixth step involves calcining the dried product in a muffle furnace. After calcination, cooling yields the co-strained Mo2C-Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0069] Example 5

[0070] The co-lattice strained Mo2C-Na2Mn8O prepared in Examples 1-4 16 Composite materials were used to prepare the positive electrode for aqueous zinc-ion batteries.

[0071] The first step is to weigh 0.16 g of Mo2C-Na2Mn8O with co-strained lattice. 16 The composite material and 0.02 g of acetylene black were placed in an agate mortar and ground thoroughly.

[0072] The second step involves dissolving 0.02 g of polyvinylidene fluoride in 0.6 mL of N-methylpyrrolidone to prepare an adhesive. After stirring evenly, the adhesive is added to the mixed powder obtained in the first step and further mixed into a uniform slurry.

[0073] The third step is to coat the obtained slurry onto the surface of a stainless steel foil with a thickness of 0.01 mm and dry it in an oven at 80 ℃ for 1 h.

[0074] The fourth step is to cut the stainless steel foil into 10 mm diameter discs after the active material has dried completely, which will be used as the positive electrode of the battery.

[0075] The fifth step involves assembling an aqueous zinc-ion battery using a zinc sheet as the negative electrode, glass fiber paper as the separator, and a mixed solution of 2 mol / L ZnSO4 and 0.2 mol / L MnSO4 as the electrolyte. After assembly, the battery is left to stand for 24 hours for subsequent electrochemical testing.

[0076] Figure 8 Mo2C-Na2Mn8O with co-strained lattice 16 The charge-discharge cycle diagram of an aqueous zinc-ion battery with the composite material as the positive electrode is shown. The charge-discharge test current segments were set at 50 mA / g, 100 mA / g, 200 mA / g, 300 mA / g, and 500 mA / g. The composite material prepared in Example 1 exhibited gradual activation characteristics at a current density of 50 mA / g, with the discharge specific capacity continuously increasing with cycling. The material prepared in Example 1 reached a discharge specific capacity of 396.2 mAh / g at the 5th cycle, demonstrating the best electrochemical activation behavior.

[0077] Figure 9 Mo2C-Na2Mn8O with co-strained lattice 16 Cyclic voltammogram of an aqueous zinc-ion battery with a composite material as the positive electrode. The oxidation and reduction peaks are sharp, and the potential difference between them is small, indicating that the electrode reaction has high reversibility and fast kinetics, with low polarization. This is attributed to the reaction between Mo₂C and Na₂Mn₈O. 16 The synergistic lattice strain induced by the two-phase composite significantly enhances the structural stability of the material, thereby effectively improving its electrochemical performance in zinc-ion batteries.

[0078] Figure 10 Mo2C-Na2Mn8O with co-strained lattice 16 The AC impedance curve of an aqueous zinc-ion battery with the composite material as the positive electrode is shown. The sample prepared in Example 1 has a low charge transfer resistance, and combined with the continuous increase in capacity during cycling, it indicates that the material achieves effective structural activation and interface optimization during electrochemical cycling.

[0079] Based on the disclosure in the foregoing specification, those skilled in the art can make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. A co-strained Mo2C-Na2Mn8O 16 The composite material is characterized by the following: its XRD pattern showing characteristic diffraction peaks at 2θ angles of 36.6°, 41.5°, and 53.5°; its XPS spectrum showing characteristic peaks at binding energies of 231.59 eV, 234.75 eV, 284.06 eV, 529.23 eV, 530.79 eV, 641.78 eV, 653.31 eV, and 1071.2 eV; wherein the oxidation state of Mn is a combination of +3 and +4.

2. The Mo2C-Na2Mn8O with synergistic lattice strain as described in claim 1 16 A method for preparing composite materials, characterized in that, Includes the following steps: The first step is to disperse sodium molybdate dihydrate solid in deionized water, and then add manganese nitrate aqueous solution, potassium permanganate solid and ammonium bicarbonate solid in sequence, and stir until they are mixed evenly. The second step is to transfer the resulting mixed solution to a hydrothermal reactor, place it in an oven for constant temperature reaction, and allow it to cool naturally to room temperature after the reaction is complete. The third step is to remove the reaction product, wash and filter it, and then dry it in an oven. The fourth step involves calcining the dried product in a muffle furnace under air atmosphere, followed by cooling to obtain the concordantly strained Mo2C-Na2Mn8O. 16 Composite materials.

3. The preparation method according to claim 2, characterized in that: In the first step, the molar ratio of sodium molybdate dihydrate to potassium permanganate is 1:

3.

4. The preparation method according to claim 2, characterized in that: In the first step, the molar ratio of potassium permanganate to manganese nitrate and ammonium bicarbonate is 3:20:

48.

5. The preparation method according to claim 2, characterized in that: In the second step, the isothermal reaction is carried out at a temperature of 160°C for 6 hours.

6. The preparation method according to claim 2, characterized in that: In the third step, the reaction product is washed with pure water. Specifically, the product is placed in pure water to form a suspension, sonicated for 5 minutes, and then filtered. This washing process is repeated a total of 5 times.

7. The preparation method according to claim 2, characterized in that: In the third step, the drying temperature is 80°C and the drying time is 1 hour.

8. The preparation method according to claim 2, characterized in that: In the fourth step, the calcination temperature is 450℃, the constant temperature calcination time is 5 hours, the time to heat up to 450℃ is 2 hours, and the time to cool down to below 200℃ after calcination is 2 hours.

9. The Mo2C-Na2Mn8O with synergistic lattice strain as described in claim 1 16 Application of composite materials in the cathode of aqueous zinc-ion batteries.

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