A pb s additive modified ago positive electrode material, a preparation method and a zinc-silver battery

Abstract

This invention relates to a PbS-modified AgO cathode material, its preparation method, and a zinc-silver battery, belonging to the field of zinc-silver battery technology. The PbS content is 1% to 5% of the AgO cathode material's mass, and it is prepared by wet mixing and ball milling. Adding PbS to the AgO cathode material and ball milling it to generate PbSO4 not only inhibits the decomposition of AgO during ball milling but also inhibits the decomposition of AgO during aging. This cathode material can extend the battery's lifespan during long-term storage of zinc-silver batteries.

Description

Technical Field

[0001] This invention relates to a PbS-modified AgO cathode material, its preparation method, and a zinc-silver battery, belonging to the field of zinc-silver battery technology. Background Technology

[0002] Zinc-silver batteries have been widely used and extensively studied in various fields due to their high specific energy, stable discharge voltage, and good safety. However, with the continuous advancement and iteration of equipment technology, these devices are not only becoming more advanced in performance, but also placing increasingly stringent requirements on their supporting energy systems. Especially for equipment requiring long-term operational capability or performing long-range missions, such as satellite platforms, deep-sea probes, and certain special-purpose missile systems, the storage life of their built-in batteries has become a key factor limiting overall performance and cost-effectiveness. Therefore, extending the storage life of zinc-silver batteries and ensuring their stable and reliable power supply throughout the entire mission cycle has become an urgent need in the current research and development of zinc-silver batteries.

[0003] The main reasons for the limited storage life of zinc-silver batteries are: ① Decomposition of the positive electrode AgO: During storage, the positive electrode material AgO is prone to decomposition, generating Ag2O and O2, leading to a reduction in active material and thus affecting the battery's discharge performance and lifespan. This is the most significant factor limiting the storage life of zinc-silver batteries; ② Oxidation of the negative electrode active material Zn: During storage, Zn reacts with oxygen and moisture in the environment, leading to oxidation, reducing the effective active material of the negative electrode, and further shortening the battery's storage life; ③ Degradation of separator performance: As a key component inside the battery, the separator's performance may gradually decline over time, affecting the stability of the electrolyte and the control of internal battery reactions, thereby indirectly shortening the battery's storage life. Therefore, a method to improve the stability of AgO is urgently needed to extend the storage life of zinc-silver batteries. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a PbS-modified AgO cathode material, a preparation method, and a zinc-silver battery. Introducing the metal sulfide additive PbS into the cathode material for modification inhibits the decomposition of AgO, thereby improving the stability of the zinc-silver battery during long-term storage and extending its storage life.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows.

[0006] A PbS-modified AgO cathode material is provided, wherein the mass of PbS is 1% to 5% of the mass of AgO cathode material. After ball milling and mixing of PbS and AgO cathode material, PbSO4 is generated, which inhibits the decomposition of AgO.

[0007] Preferably, the mass of PbS is 2.5% to 3.5% of the mass of the AgO cathode material.

[0008] Preferably, the total mass of the AgO cathode material is 100%, and the raw material composition and its mass percentage are AgO 90%~95%, Ag2O 1%~4%, and Ag 4%~6%.

[0009] A method for preparing PbS-modified AgO cathode material according to the present invention includes the following steps:

[0010] PbS and AgO cathode materials were mixed, and then wet-milled with organic solvent at 200–400 r / min for 3–12 h. After milling, the mixture was dried in a forced-air dryer at 50–60 °C for 8–12 h to obtain a PbS-modified AgO cathode material.

[0011] Preferably, during wet ball milling, the diameter of the milling beads is 6–10 mm.

[0012] Preferably, during wet ball milling, the organic solvent is cyclohexane, tetrahydrofuran, acetonitrile, or isopropanol. More preferably, it is isopropanol.

[0013] A zinc-silver battery, wherein the positive electrode material of the battery is a PbS-modified AgO positive electrode material as described in this invention.

[0014] Beneficial effects

[0015] In this invention, PbS is added to the AgO cathode material, and PbSO4 is generated after ball milling. This not only inhibits the decomposition of AgO during ball milling but also inhibits the decomposition of AgO during aging. The cathode material can extend the service life of zinc-silver batteries during long-term storage. Attached Figure Description

[0016] Figure 1 This is a SEM image of the cathode material in Comparative Example 1.

[0017] Figure 2 The image shows the SEM image of the cathode material in Comparative Example 2.

[0018] Figure 3 This is a SEM image of the cathode material in Example 1.

[0019] Figure 4 The images show the XRD patterns of the cathode materials in Examples 1-2 and Comparative Example 1.

[0020] Figure 5 The XRD patterns are for the cathode materials in Comparative Examples 1-3.

[0021] Figure 6 The images show the TG values ​​of the cathode materials in Example 1 and Comparative Example 2.

[0022] Figure 7 The TG curves are for the cathode materials in Example 2 and Comparative Example 3.

[0023] Figure 8 The Ag 3d and O1s plots are fitted based on XPS tests of the cathode materials in Comparative Examples 2-3 and Examples 1-2.

[0024] Figure 9 The diagram shows the proportions of AgO, Ag2O, and Ag calculated from the Ag 3d total spectra of Comparative Examples 2-3 and Examples 1-2.

[0025] Figure 10 The image shows the Pb 4f plot fitted by XPS testing of the cathode material in Examples 1-2.

[0026] Figure 11 The S2p plot is fitted based on the XPS test results of the cathode material in Examples 1-2. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments.

[0028] To verify the extended storage life of the modified AgO cathode, an AgO electrode stored for 14 years was obtained through a high-temperature accelerated storage method. The high-temperature accelerated storage method described in this invention involves placing the material in a vacuum oven at 70°C for 256 hours. The principle is as follows:

[0029] The decomposition kinetic equations for the aging and accelerated aging processes of AgO, the main component of the AgO cathode material at room temperature, are as follows:

[0030] K1=A1exp(-E a1 / RT1) (1)

[0031] K2=A2exp(-E a2 / RT2) (2)

[0032] Where E a =116.56 kJ mol -1 A = 17.20s -1 .

[0033] Due to the different temperatures at which AgO decomposes, the corresponding E a It is not much different from A, therefore:

[0034]

[0035] Therefore, when T1 = 298 K (25℃) and T2 = 343 K (70℃), the corresponding reaction rate constant K2 / K1 is 479.25.

[0036] For the solid-phase reaction 2AgO + Ag → Ag₂O, the relationship between the equilibrium constant and storage time at a given temperature is as follows:

[0037]

[0038] Where n is the number of sample storage temperature ranges, m i0 Let m be the initial mass of the i-th sample segment. i Let t be the mass after the i-th segment of storage is completed. i The storage time is K. Under constant temperature conditions, K = (m0-m) / t. Since the initial mass is the same, the value of (m0-m) is the same when the decomposition reaches the same retention rate. From equation (4), we can get t1 / t2 = K2 / K1. For a positive electrode stored for 14 years, t1 is 5110 days, and t2 = 10.66 days.

[0039] Therefore, placing the cathode material in a vacuum oven at 70°C for 256 hours can achieve the same result as storing it at room temperature for 14 years.

[0040] SEM characterization: Instrument: Thermo Fisher Scientific FEI-Quanta 250, voltage: 25kV.

[0041] XRD characterization: Instrument: Rigaku Ultima IV, Japan; scanning angle: 10–80°; scanning speed: 5° / min.

[0042] TG characterization: Instrument: WCT-D from Beijing Beiguang Century Instrument Co., Ltd., heating rate: 5℃ / min, temperature range: 30℃~800℃.

[0043] XPS characterization: Instrument: PHIQUANTERA-II SXM from ULVAC-PHI Corporation, Japan.

[0044] Example 1

[0045] (1) Preparation of positive electrode materials: Weigh 0.9021g AgO, 0.0282g Ag2O, 0.0397g Ag and 0.0300g PbS according to the following proportions: AgO mass fraction 90.21%, Ag2O mass fraction 2.82%, Ag mass fraction 3.97% and PbS mass fraction 3.0%. Place them in a mortar and grind for about 30 minutes to mix evenly.

[0046] (2) Ball milling: Add 6 mm diameter ball milling beads that occupy 2 / 3 of the volume of the ball milling jar to the ball milling jar, put the uniformly mixed positive electrode material into the ball milling jar, add 5 mL of isopropanol as solvent, and ball mill for 3 h at a speed of 200 r / min.

[0047] (3) Drying: Collect the ball-milled material and dry it in a forced-air drying oven at 50°C for 8-12 hours to obtain a PbS-modified AgO cathode material.

[0048] Example 2

[0049] The AgO cathode material modified with PbS additive obtained in Example 1 was placed in a vacuum oven at 70°C for 256 hours.

[0050] Comparative Example 1

[0051] (1) Preparation of positive electrode material: Weigh 0.9300g AgO, 0.0290g Ag2O and 0.0410g Ag according to the mass fraction of AgO of 93.00%, Ag2O of 2.90% and Ag of 4.10%, put them into a mortar and grind for about 30 minutes, mix them evenly, and obtain an AgO positive electrode material.

[0052] Comparative Example 2

[0053] (1) Preparation of positive electrode materials: Weigh 0.9300g AgO, 0.0290g Ag2O and 0.0410g Ag according to the mass fraction of AgO of 93.00%, Ag2O of 2.90% and Ag of 4.10%, put them into a mortar and grind for about 30 minutes to mix evenly.

[0054] Steps (2)-(3) are the same as in Example 1, resulting in an AgO cathode material.

[0055] Comparative Example 3

[0056] (1) Place the dried material from Comparative Example 2 in a vacuum oven at 70°C for 256 hours.

[0057] The SEM test results of the cathode materials described in Comparative Examples 1-2 and Example 1 are as follows: Figure 1-3 As shown, in Comparative Example 1, the unmilled material particles are uniform in size and evenly distributed; in Comparative Example 2, the milled material particles are broken and smaller in size, but show obvious agglomeration; in Example 1, the material particles after ball milling with PbS are relatively uniform, with slight agglomeration. This indicates that PbS has a certain degree of improvement on the damage to the material morphology caused by ball milling.

[0058] The XRD test results of the cathode materials described in Comparative Examples 1-3 and Examples 1-2 are as follows: Figure 4-5 As shown, compared to the cathode material described in Comparative Example 2, strong diffraction peaks were observed at 2θ of 32.01°, 32.28°, 34.17°, 37.18°, and 39.38°, corresponding to the (200), (111), (002), (111), and (202) crystal planes of AgO (PDF#43-1038). However, the diffraction peak intensity of Comparative Example 3 was significantly weakened, indicating that AgO decomposed during the aging process. Compared to Example 1, the diffraction intensity of the (111) crystal plane of AgO in the material described in Example 2 was weakened to a certain extent, while the diffraction intensity of other crystal planes changed only slightly, proving that PbS has a certain inhibitory effect on AgO decomposition during the aging process.

[0059] This inhibitory effect was further quantitatively verified by TG testing. The TG test results of the cathode materials described in Comparative Examples 1-3 and Examples 1-2 are as follows: Figure 6-7 As shown in Table 1, the proportions of AgO, Ag₂O, and Ag in the material can be calculated from the weight loss rates of the two platforms. In Example 1, after introducing PbS into the AgO cathode material, the proportion of AgO increased from 55.80% to 73.32%, indicating that the introduction of PbS inhibited the decomposition of AgO during ball milling. To quantitatively describe the inhibitory effect of PbS on AgO decomposition, the retention rate of AgO proportion after aging compared to before aging was calculated, as shown in Table 2. The AgO retention rate increased from 82.50% to 87.52%, indicating that the introduction of PbS inhibited the decomposition of AgO during aging, which is consistent with the XRD results.

[0060] Table 1

[0061]

[0062] Table 2

[0063]

[0064] XPS tests were performed on the materials from Examples 2-3 and 1-2. The fitted spectra of Ag 3d and O1s are shown below. Figure 8 As shown, Ag exists primarily in the material in the forms of +3, +1, and 0 valences; O exists mainly in the form of metal-oxygen bonds (MO bonds), with a portion existing as Ag-O2, due to the presence of elemental Ag which combines with O2 in the air. Although XPS, as a semi-quantitative surface analysis technique, cannot precisely reflect the true internal composition of a material, it can still effectively reveal overall trends and serve as an auxiliary verification method for TG test results. By analyzing the proportions of Ag in different valence states in the XPS total spectrum, the relative contents of AgO, Ag2O, and elemental Ag were calculated and plotted as a bar chart. The results are shown in [Figure number missing]. Figure 9 The results are largely consistent with the TG test results. The proportion of AgO in the cathode material described in Example 1 increased significantly, indicating that the introduction of PbS helps to suppress the decomposition of AgO during the ball milling and aging processes. In Example 2, the proportion of AgO in the aged material was higher than that in Comparative Example 3, proving that the introduction of PbS helps to suppress the decomposition of AgO during the aging process.

[0065] Based on the above analysis, the introduction of PbS helps to suppress the decomposition of AgO during the ball milling and aging processes.

[0066] XPS fitting results for Pb4f and S2p in the material after introducing PbS are as follows: Figure 10 and Figure 11 As shown in the figure, according to the fitting results, Pb exhibits characteristic peaks at 137.8 eV and 142.6 eV, corresponding to Pb-O and Pb-S bonds, respectively, while S shows obvious characteristic peaks at 163.4 eV and 168.4 eV, corresponding to S-Pb and SO bonds. This indicates that the introduction of PbS generates PbSO4 after ball milling, and this product plays a role in inhibiting the decomposition of AgO during the ball milling and aging processes.

[0067] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.

Claims

1. An AgO cathode material modified with PbS additive for zinc-silver batteries, characterized in that: The mass of PbS is 1% to 5% of the mass of AgO cathode material. After ball milling and mixing PbS and AgO cathode material, PbSO4 is generated, which inhibits the decomposition of AgO.

2. The AgO cathode material modified with PbS additive for zinc-silver batteries as described in claim 1, characterized in that: The mass of PbS is 2.5% to 3.5% of the mass of AgO cathode material.

3. A method for preparing a PbS-modified AgO cathode material for zinc-silver batteries as described in claim 1 or 2, characterized in that: The method steps include: PbS and AgO cathode materials were mixed, and organic solvent was added at 200~400 r / min for wet ball milling for 3~12 h. After ball milling, the mixture was dried at 50~60℃ for 8~12 h to obtain a PbS-modified AgO cathode material.

4. The preparation method of the AgO cathode material modified with PbS additive for zinc-silver batteries as described in claim 3, characterized in that: In wet ball milling, the diameter of the milling beads is 6~10mm.

5. The preparation method of the PbS-modified AgO cathode material for zinc-silver batteries as described in claim 3, characterized in that: During wet ball milling, the organic solvent is cyclohexane, tetrahydrofuran, acetonitrile, or isopropanol.

6. The method for preparing a PbS-modified AgO cathode material for zinc-silver batteries as described in claim 5, characterized in that: The organic solvent is isopropanol.

7. A zinc-silver battery, characterized in that: The positive electrode material of the battery is an AgO positive electrode material modified with PbS additive for zinc-silver batteries as described in claim 1 or 2.

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