Energy storage lead-carbon battery negative electrode material and preparation method thereof

Abstract

The invention relates to the technical field of batteries, and provides an energy storage lead-carbon battery negative electrode material and a preparation method thereof. The negative electrode material of the energy storage lead-carbon battery is prepared from the following materials in parts by weight: 0.1 to 0.15 part of lignosulfonate, 0.2 to 0.3 part of humic acid, 0.5 to 1.5 parts of barium sulfate, 0.3 to 0.5 part of conductive carbon black, 10 to 12 parts of biomass derived lead-carbon composite framework and 85 to 95 parts of lead powder. According to the negative electrode material for the energy storage lead-carbon battery, the problems of electrochemical reaction kinetics and interface resistance are solved, so that the service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a negative electrode material for an energy storage lead-carbon battery and a preparation method thereof. Background Art

[0002] With the global energy transition and the increasing emphasis on renewable energy, energy storage technology has become crucial for resolving energy supply and demand imbalances and improving energy efficiency. Lead-carbon batteries, as cost-effective energy storage devices, offer broad application prospects in areas such as grid peak regulation and distributed energy storage. As a core component of lead-carbon batteries, the performance of the anode material directly impacts their overall performance.

[0003] The primary function of the negative electrode material in lead-carbon energy storage batteries is to participate in the electrochemical reactions during the battery's charge and discharge processes. During charging, the lead (Pb) in the negative electrode material is oxidized to lead sulfate (PbSO₄). Simultaneously, the carbon material provides more active sites, promoting uniform lead sulfate deposition and reducing lead dendrite growth, thereby improving the battery's charge acceptance and cycling stability. During discharge, the lead sulfate is reduced back to lead, and the carbon material acts as a conductive network, improving electron conduction efficiency and reducing the battery's internal resistance. Currently, commonly used carbon materials include activated carbon, carbon nanotubes, and graphene. These carbon materials have different structural and performance characteristics, and their impact on the performance of the lead-carbon battery negative electrode varies.

[0004] Although the addition of carbon materials can improve the cycle life of lead-carbon batteries to a certain extent, the existing negative electrode materials still have the problem of rapid capacity decay during long-term cycles. This is mainly because during the charge and discharge cycle, the negative electrode material will undergo volume changes, resulting in a weakening of the binding force between the active material and the current collector, and some active materials will fall off, thereby reducing the capacity of the battery. In addition, the deposition and dissolution process of lead sulfate on the negative electrode surface will also lead to the destruction of the negative electrode structure, further affecting the cycle life of the battery. In addition, the charging acceptance capacity of the existing energy storage lead-carbon battery negative electrode material is limited, and polarization is prone to occur during fast charging, resulting in reduced battery charging efficiency and even affecting the service life of the battery. This is mainly because the electrochemical reaction kinetics between lead and sulfuric acid in the negative electrode material are slow, and the interface resistance between the carbon material and lead is large, which limits the transmission speed of electrons and ions. Based on this, the present invention proposes a negative electrode material for energy storage lead-carbon batteries and a preparation method thereof. Summary of the Invention

[0005] The present invention proposes a negative electrode material for an energy storage lead-carbon battery and a preparation method thereof, which improves the problem of rapid capacity decay of existing negative electrode materials for energy storage lead-carbon batteries during long-term cycles, enhances the charge acceptance of existing negative electrode materials for energy storage lead-carbon batteries, reduces polarization during rapid charging, and improves the problem of limited electron and ion transmission speed caused by the slow electrochemical reaction kinetics of the negative electrode material and the large interface resistance between the carbon material and lead, thereby extending the battery life.

[0006] The technical solutions of the present invention are as follows: In a first aspect, the present invention provides a negative electrode material for an energy storage lead-carbon battery, comprising the following raw materials in parts by weight: 0.1-0.15 parts of lignin sulfonate, 0.2-0.3 parts of humic acid, 0.5-1.5 parts of barium sulfate, 0.3-0.5 parts of conductive carbon black, 10-12 parts of a biomass-derived lead-carbon composite skeleton, and 85-95 parts of lead powder.

[0007] As a further technical solution, the method for preparing the biomass-derived lead-carbon composite skeleton includes: (1) Wash the rice husk with hydrochloric acid, then ball-mill it to 150-250 mesh, and soak it in a mixture of nickel nitrate solution and F127 ethanol solution; (2) adding MgO nanoparticles and CaCO3 nanoparticles, ball-milling the mixture, heating it up and pyrolyzing it once, cooling it to room temperature, and taking out the carbonized product; (3) The carbonized product is mixed with KOH particles and then subjected to secondary pyrolysis to obtain an activated product; (4) The activated product was soaked in NaOH solution, then soaked in citric acid solution, washed and dried to obtain a 3D-HPC skeleton; (5) The 3D-HPC skeleton was immersed in a mixed solution of Pb(CH3COO)2 and H3BO3 in ethanol and water, and ultrasonic-assisted impregnation was performed. Nano-lead particles were generated by in-situ reduction and then cooled to obtain a lead-carbon composite skeleton Pb@3D-HPC.

[0008] As a further technical solution, the average particle size of the MgO nanoparticles is 50-100 nm; the average particle size of the CaCO3 nanoparticles is 20-50 nm.

[0009] As a further technical solution, the primary pyrolysis step includes: heating from room temperature to 260-300°C at 2°C / min, then heating to 750-800°C at 5°C / min, and keeping warm for 2-3 hours; wherein, when the temperature is raised to 400-500°C, a mixture of CH4 and N2 with a volume ratio of 5-10:90-95 is introduced and maintained for 30-40 minutes.

[0010] As a further technical solution, after the primary pyrolysis is completed, pure N2 is purged at 750-800°C for 30-40 minutes.

[0011] As a further technical solution, the mass ratio of the carbonized product to the KOH particles is 1:1.5-1:2.5.

[0012] As a further technical solution, the secondary pyrolysis step includes: heating to 700-750°C at 5°C / min under N2 atmosphere and keeping warm for 60-90 minutes.

[0013] As a further technical solution, the soaking time of the NaOH solution is 10-12 hours, and the temperature is 75-85°C; the soaking time of the citric acid solution is 6-8 hours, and the temperature is 55-65°C.

[0014] As a further technical solution, the in-situ reduction step includes: raising the temperature to 250-350°C at 3°C / min in an N2 / H2 atmosphere with a volume ratio of 90-95:5-10, and keeping the temperature for 1-2 hours.

[0015] In a second aspect, the present invention proposes a method for preparing a negative electrode material for an energy storage lead-carbon battery, the steps comprising: first mixing lignin sulfonate, humic acid, barium sulfate, conductive carbon black, and a biomass-derived lead-carbon composite skeleton, and mechanically stirring to obtain a uniformly dispersed powder; adding the above powder to lead powder and mechanically stirring to obtain a uniformly dispersed mixture; placing the above mixture in a paste mixer, adding water, and continuously stirring until the density is 4.1-4.5 g / mL to obtain a uniformly mixed lead paste; evenly applying the lead paste to the grid, the lead paste filling the through holes on the metal lead grid, and curing and drying to obtain the lead-carbon battery negative electrode material.

[0016] The working principle and beneficial effects of the present invention are: The present invention simultaneously uses MgO and CaCO3 nanoparticles of two different sizes and decomposition temperatures as dual templates. During the pyrolysis process, MgO decomposes at high temperature to leave macropores / mesopores, and CaCO3 decomposes at lower temperatures to leave smaller mesopores / micropores. This synergistic effect constructs a through-hole macropore-mesopore-micropore gradient pore structure. The presence of macropores is conducive to the rapid transmission of electrolyte, allowing the electrolyte to quickly reach the interior of the electrode and reduce the resistance to ion transmission; the mesopores provide a high specific surface area and abundant active sites, increasing the contact area between the electrode and the electrolyte, which is conducive to the electrochemical reaction; the micropores enhance the stability of the structure and prevent the electrode from structural collapse during the charge and discharge process. This optimized pore structure is significantly superior to a single template or disordered pore structure, greatly improving the active material loading, ion diffusion rate and structural stability, thereby improving the charge and discharge performance and cycle life of the battery.

[0017] The present invention utilizes in situ catalytic CNT growth to strengthen the conductive network, wherein nickel is reduced to nanoparticles, catalytically cracking CH4 to in situ grow carbon nanotubes (CNTs) on the surface and internal pore walls of the carbon skeleton. These in situ-grown CNTs act like "rebar," tightly connecting the various parts of the carbon skeleton to form a highly interconnected, intrinsic three-dimensional conductive network. This three-dimensional conductive network significantly enhances the electron conductivity of the entire skeleton, resolving the issues of uneven dispersion and high contact resistance associated with traditional mechanically mixed conductive agents (such as carbon black). The in situ-grown CNTs are tightly bonded to the carbon skeleton, better adapting to the volume changes of the electrode during charge and discharge, ensuring the stability of the conductive network, thereby improving the battery's charge acceptance and rapid charging performance, and reducing polarization during rapid charging.

[0018] The present invention uses solid KOH particles to physically mix with the carbonized product for activation, rather than the traditional KOH solution impregnation. Solid-state mixing avoids the risk of pore blockage and skeleton swelling / collapse that may be caused by solution impregnation. During the activation process, KOH gradually melts and penetrates, achieving gradient activation from the outside to the inside. This gradient activation method helps to efficiently etch and generate abundant micropores and mesopores while maintaining the integrity of the skeleton's macroscopic structure, thereby obtaining a higher specific surface area and a more optimized pore distribution. Compared with the solution impregnation method, solid-state KOH gradient activation can better protect the structure of the brittle biomass carbon skeleton, allowing the electrode to maintain a stable pore structure and conductive properties during the charge and discharge process, thereby improving the cycle stability and service life of the battery.

[0019] In this invention, a weak organic acid such as citric acid or acetic acid is used instead of a strong inorganic acid (such as HCl) to remove the CaCO3 template. The mild nature of the weak acid environment reduces damage to the carbon skeleton (particularly newly formed CNTs and surface functional groups). More importantly, citric acid itself contains carboxyl groups, and the treatment process introduces more oxygen-containing functional groups (particularly -COOH) onto the carbon skeleton surface. These functional groups significantly enhance the skeleton's hydrophilicity and affinity for lead ions / PbSO4, facilitating the subsequent uniform deposition and conversion reaction kinetics of lead. During the battery's charge and discharge processes, lead ions can more easily deposit and dissolve on the carbon skeleton surface, increasing the electrode's reactivity and reducing polarization, thereby improving the battery's charge and discharge performance and cycle life.

[0020] After obtaining the functionalized 3D-HPC skeleton, the present invention uses solution impregnation combined with low-temperature reduction technology to pre-deposit nano-scale lead crystals in situ inside and on the surface of the skeleton. These lead seeds act as "anchor points" and "nucleation centers". During the subsequent mixing with a large amount of lead powder and plate curing process, they can guide the lead powder particles to grow and deposit preferentially in the pores and surface of the skeleton to form a compact and uniform lead-carbon complex. This molecular / nanoscale interface bonding greatly enhances the physical bonding force and electrical contact between the lead active substance and the carbon skeleton, significantly reducing the interfacial resistance and active substance shedding problems caused by traditional mechanical mixing. The presence of nano-lead seeds also increases the lead deposition / dissolution reaction activity, enabling the electrode to undergo electrochemical reactions more quickly during the charge and discharge process, reducing polarization, and improving the battery's charge acceptance and cycle stability. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] Example 1 This embodiment provides a negative electrode material for an energy storage lead-carbon battery, comprising the following materials in parts by weight: 0.12 parts of sodium lignin sulfonate, 0.25 parts of humic acid, 1 part of barium sulfate, 0.4 parts of conductive carbon black, 11 parts of a biomass-derived lead-carbon composite skeleton, and 90 parts of lead powder; The preparation method of the biomass-derived lead-carbon composite skeleton includes: (1) Rice husks were soaked in 1M hydrochloric acid for 24 h to remove impurities, washed with deionized water until neutral, dried at 80 °C, and ball-milled to 180 mesh to obtain rice husk powder. The powder was mixed with 0.8 wt% nickel nitrate aqueous solution and 8 wt% F127 ethanol solution at a ratio of 1:10 g / mL, ultrasonically dispersed for 1 h, and allowed to soak for 24 h. (2) After adding MgO nanoparticles with an average particle size of 80 nm and CaCO3 nanoparticles with an average particle size of 40 nm and ball milling and mixing for 3 hours, the weight ratio of rice husk powder, MgO nanoparticles and CaCO3 nanoparticles is 10:2:1; wherein, when the temperature is raised to 450°C, a mixture of CH4 and N2 with a volume ratio of 8:92 is introduced and maintained for 35 minutes for a pyrolysis, and pure N2 is purged at 7800°C for 35 minutes, cooled to room temperature, and the carbonized product is taken out; (3) After mixing the carbonized product with KOH particles at a mass ratio of 1:2, the temperature was raised to 720°C at a rate of 5°C / min under a N2 atmosphere and kept at that temperature for 70 min for secondary pyrolysis to obtain the activated product; (4) The activated product was soaked in a 2M NaOH aqueous solution at 80°C for 11 h, then soaked in a 1M citric acid aqueous solution at 60°C for 7 h, washed with deionized water until neutral, and dried in a vacuum at 80°C to obtain a 3D-HPC skeleton; (5) The 3D-HPC skeleton was immersed in a mixed solution of 0.2M Pb(CH3COO)2 and 0.08M H3BO3 in ethanol and water, and ultrasonically assisted impregnation was performed for 1.5 h. The temperature was raised to 300 °C at 3 °C / min in a N2 / H2 atmosphere with a volume ratio of 92:8 and kept for 1.5 h. The lead nanoparticles were in situ reduced and cooled to obtain the lead-carbon composite skeleton Pb@3D-HPC.

[0023] Example 2 This embodiment provides a negative electrode material for an energy storage lead-carbon battery, comprising the following materials in parts by weight: 0.1 parts of sodium lignin sulfonate, 0.2 parts of humic acid, 0.5 parts of barium sulfate, 0.3 parts of conductive carbon black, 10 parts of a biomass-derived lead-carbon composite skeleton, and 85 parts of lead powder; The preparation method of the biomass-derived lead-carbon composite skeleton includes: (1) Rice husks were soaked in 1M hydrochloric acid for 24 h to remove impurities, washed with deionized water until neutral, dried at 80 °C, and ball-milled to 150 mesh to obtain rice husk powder. The powder was then mixed with 0.5 wt% nickel nitrate aqueous solution and 8 wt% F127 ethanol solution at a ratio of 1:8 g / mL, ultrasonically dispersed for 1 h, and allowed to soak for 24 h. (2) After adding MgO nanoparticles with an average particle size of 50 nm and CaCO3 nanoparticles with an average particle size of 20 nm and ball-milling and mixing for 2 h, the weight ratio of rice husk powder, MgO nanoparticles and CaCO3 nanoparticles is 8:2:1; the temperature is raised from room temperature to 260 ° C at 2 ° C / min, and then raised to 750 ° C at 5 ° C / min, and kept warm for 2 h; wherein, when the temperature is raised to 400 ° C, a mixture of CH4 and N2 with a volume ratio of 5:95 is introduced, and the mixture is maintained for 30 min for a pyrolysis, and pure N2 is purged at 750 ° C for 30 min, cooled to room temperature, and the carbonized product is taken out; (3) After mixing the carbonized product with KOH particles at a mass ratio of 1:1.5, the mixture was heated to 700 °C at a rate of 5 °C / min under a N2 atmosphere and kept at that temperature for 60 min for secondary pyrolysis to obtain the activated product; (4) The activated product was soaked in a 2M NaOH aqueous solution at 75°C for 10 h, then soaked in a 1M citric acid aqueous solution at 55°C for 6 h, washed with deionized water until neutral, and dried in a vacuum at 80°C to obtain a 3D-HPC skeleton; (5) The 3D-HPC skeleton was immersed in a mixed solution of 0.1M Pb(CH3COO)2 and 0.05M H3BO3 in ethanol and water, and ultrasonically assisted impregnation was performed for 1 h. The temperature was raised to 250°C at 3°C / min in a N2 / H2 atmosphere with a volume ratio of 90:10 and kept for 1 h. The lead nanoparticles were in situ reduced and cooled to obtain the lead-carbon composite skeleton Pb@3D-HPC.

[0024] Example 3 This embodiment provides a negative electrode material for an energy storage lead-carbon battery, comprising the following materials in parts by weight: 0.15 parts of sodium lignin sulfonate, 0.3 parts of humic acid, 1.5 parts of barium sulfate, 0.5 parts of conductive carbon black, 12 parts of a biomass-derived lead-carbon composite skeleton, and 95 parts of lead powder; The preparation method of the biomass-derived lead-carbon composite skeleton includes: (1) Rice husks were soaked in 1M hydrochloric acid for 24 h to remove impurities, washed with deionized water until neutral, dried at 80 °C, and ball-milled to 250 mesh to obtain rice husk powder. The powder was then mixed with 1.0 wt% nickel nitrate aqueous solution and 8 wt% F127 ethanol solution at a ratio of 1:12 g / mL, ultrasonically dispersed for 1 h, and allowed to soak for 24 h. (2) After adding MgO nanoparticles with an average particle size of 100 nm and CaCO3 nanoparticles with an average particle size of 50 nm and ball milling and mixing for 4 hours, the weight ratio of rice husk powder, MgO nanoparticles and CaCO3 nanoparticles is 12:2:1; the temperature is raised from room temperature to 300°C at 2°C / min, and then raised to 800°C at 5°C / min, and kept warm for 3 hours; wherein, when the temperature is raised to 500°C, a mixed gas containing CH4 and N2 with a volume ratio of 10:90 is introduced, and maintained for 40 minutes for a pyrolysis, and then purged with pure N2 at 800°C for 40 minutes, cooled to room temperature, and the carbonized product is taken out; (3) After mixing the carbonized product with KOH particles at a mass ratio of 1:2.5, the mixture was heated to 750°C at a rate of 5°C / min under a N2 atmosphere and kept at that temperature for 90 min for secondary pyrolysis to obtain the activated product; (4) The activated product was soaked in a 2M NaOH aqueous solution at 85°C for 12 h, then soaked in a 1M citric acid aqueous solution at 65°C for 8 h, washed with deionized water until neutral, and dried in a vacuum at 80°C to obtain a 3D-HPC skeleton; (5) The 3D-HPC skeleton was immersed in a mixed solution of 0.3M Pb(CH3COO)2 and 0.1M H3BO3 in ethanol and water, and ultrasonically assisted impregnation was performed for 2 h. The temperature was raised to 350°C at 3°C / min in a N2 / H2 atmosphere with a volume ratio of 95:5 and kept for 2 h. The lead nanoparticles were in situ reduced and cooled to obtain the lead-carbon composite skeleton Pb@3D-HPC.

[0025] Preparation Example 1 The steps for preparing the negative electrode material of the energy storage lead-carbon battery in Examples 1-3 include: mixing lignin sulfonate, humic acid, barium sulfate, conductive carbon black, and a biomass-derived lead-carbon composite skeleton, and mechanically stirring to obtain a uniformly dispersed powder; adding the above powder to lead powder and mechanically stirring to obtain a uniformly dispersed mixture; placing the above mixture in a paste mixer, adding water, and continuously stirring until the density is 4.2 g / mL to obtain a uniformly mixed lead paste with a thickness of 1.2 mm; evenly applying the lead paste to the grid, filling the through holes on the metal lead grid, curing at 40°C and 85% RH for 12 h, drying at 55°C for 24 h, and curing at 75°C and 95% RH for 48 h to obtain the negative electrode material of the lead-carbon battery.

[0026] Comparative Example 1 In this comparative example, there is no MgO template, and only CaCO3 nanoparticles are added in step (2), and the rest is the same as in Example 1.

[0027] Comparative Example 2 In this comparative example, there is no CaCO3 template, and only MgO nanoparticles are added in step (2), and the rest is the same as in Example 1.

[0028] Comparative Example 3 In this comparative example, Ni(NO3)2 was not added and CH4 was not passed, and the rest was the same as in Example 1.

[0029] Comparative Example 4 In this comparative example, activation was performed by immersion in a KOH solution, and the rest was the same as in Example 1. Step (3) was replaced by: immersing the carbonized product in a 6MKOH solution for 24 h, drying, heating to 720°C at a rate of 5°C / min under a N2 atmosphere, and maintaining the temperature for 70 min for secondary pyrolysis to obtain an activated product; the mass ratio of the carbonized product to KOH was 1:2.

[0030] Comparative Example 5 In this comparative example, there is no lead seed deposition, i.e., no step (5), and the rest is the same as in Example 1.

[0031] Comparative Example 6 In this comparative example, 1 M HCl was used instead of citric acid, and the rest was the same as in Example 1.

[0032] Comparative Example 7 In this comparative example, the amount of biomass-derived lead-carbon composite skeleton is reduced to 5 parts, the amount of lead powder is increased to 96 parts, and the rest is the same as in Example 1.

[0033] Comparative Example 8 In this comparative example, commercial coconut shell activated carbon (specific surface area 1800m 2 / g) to replace the Pb@3D-HPC skeleton, and the rest is the same as in Example 1.

[0034] Preparation Example 2 Referring to the steps in Preparation Example 1, the raw materials in Comparative Examples 1-8 were used to prepare negative electrode materials for energy storage lead-carbon batteries.

[0035] Test Example 1: The prepared energy storage lead-carbon battery negative electrode material was assembled into a closed lead-acid battery. The positive electrode was a lead-antimony alloy grid coated with PbO2 paste, the diaphragm used was a 0.8mm AGM diaphragm, the outer shell was an ABS plastic shell, the pole was sealed, and the injection density was 1.28g / cm 3 The battery was allowed to stand for 4 hours to soak in H2SO4 electrolyte; the formation process was as follows: 0.05C constant current charging to 2.4V, 2.4V constant voltage charging to current ≤ 0.01C, and standing for 2 hours; 0.1C charge / discharge cycle was repeated 3 times.

[0036] Initial capacity: Discharge to 10.5V at 0.2C at 25°C according to GB / T 5008.1-2013 standard; and test the initial capacity loss rate after 28 days of storage at 25°C. Charge and discharge capacity retention rate: The battery is charged at a current of 0.2C to 2.4V / cell, then switched to constant voltage charging until the current is ≤0.05C; discharged at a current of 0.5C to 1.75V / cell; the charge and discharge are repeated 500 times, and the capacity retention rate is recorded. HRPSoC cycle: The battery with 0% state of charge is charged with a current of 0.1C to a cut-off voltage of 2.4V, then charged at a constant voltage of 2.4V for 12 hours and left for 10 minutes; then discharged with a current of 1C to 50% SoC (partial state of charge 0); finally, a high-rate charge and discharge cycle is performed. The cycle steps are as follows: charge with a current of 1C or 2C for 60 seconds, leave for 10 seconds, discharge with a current of 1C or 2C for 60 seconds, and leave for 10 seconds. The voltage across the battery is recorded during the charge and discharge cycle. When the discharge voltage reaches the cut-off voltage of 1.7V, the battery fails.

[0037] The results are shown in Table 1: Table 1

[0038] In summary, the number of cycles and capacity retention of HRPSoC in comparative example 1 are significantly lower than those in example 1. The lack of MgO template leads to insufficient mesoporous structure, which weakens the electrolyte wettability and ion transfer efficiency and accelerates cycle attenuation.

[0039] The self-discharge rate of Comparative Example 2 without the CaCO3 template was much higher than that of Example 1, and the capacity retention was low. The lack of the CaCO3 template reduced the microporous structure, allowing lead sulfate to accumulate, leading to increased self-discharge and capacity loss.

[0040] The number of cycles and capacity retention of HRPSoC in Comparative Example 3 were severely reduced. The lack of Ni catalyst and CH4 resulted in the absence of CNTs in the carbon skeleton, which destroyed the conductive network and deteriorated the high-rate performance.

[0041] All properties of the KOH solution immersion activation in Comparative Example 4 were inferior to those in Example 1. The wet activation resulted in uneven KOH distribution, insufficient specific surface area and porosity, and affected the active material loading and reaction kinetics.

[0042] Comparative Example 5 HRPSoC has poor cycle times and capacity retention. It lacks in-situ reduced nano-lead seeds, and the interface between the carbon skeleton and the lead powder is weak. It is easy to fall off during charging and discharging, and the cycle stability collapses.

[0043] The self-discharge rate of Comparative Example 6 is higher than that of Example 1, and the capacity retention rate is reduced. The strong acid (HCl) corrodes the carbon skeleton, destroying the integrity of the pore structure, leading to increased side reactions and capacity decay.

[0044] In Comparative Example 7, the composite skeleton dosage was halved, resulting in the lowest initial capacity and an increased self-discharge rate. Insufficient composite skeletons resulted in a sparse conductive network, reduced lead powder utilization, and a weakened ability to inhibit sulfation.

[0045] Comparative Example 8 exhibited poor performance across the board, with HRPSoC lasting only 3,800 cycles and a self-discharge rate of 18.2%. Commercial activated carbon lacks a customized multi-level pore structure and in-situ lead loading, resulting in poor interfacial compatibility and an inability to synergistically enhance battery performance.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A negative electrode material for an energy storage lead-carbon battery, characterized in that: The invention comprises the following raw materials in parts by weight: 0.1-0.15 parts of lignin sulfonate, 0.2-0.3 parts of humic acid, 0.5-1.5 parts of barium sulfate, 0.3-0.5 parts of conductive carbon black, 10-12 parts of biomass-derived lead-carbon composite skeleton, and 85-95 parts of lead powder.

2. The negative electrode material for an energy storage lead-carbon battery according to claim 1, characterized in that: The method for preparing the biomass-derived lead-carbon composite skeleton comprises: (1) Wash the rice husk with hydrochloric acid, then ball-mill it to 150-250 mesh, and soak it in a mixture of nickel nitrate solution and F127 ethanol solution; (2) adding MgO nanoparticles and CaCO3 nanoparticles, ball-milling the mixture, heating it for a first pyrolysis, cooling it to room temperature, and taking out the carbonized product; (3) The carbonized product is mixed with KOH particles and then subjected to secondary pyrolysis to obtain an activated product; (4) The activated product was soaked in NaOH solution, then soaked in citric acid solution, washed and dried to obtain a 3D-HPC skeleton; (5) The 3D-HPC skeleton was immersed in a mixed solution of Pb(CH3COO)2 and H3BO3 in ethanol and water, and ultrasonic-assisted impregnation was performed. Nano-lead particles were generated by in-situ reduction and then cooled to obtain a lead-carbon composite skeleton Pb@3D-HPC.

3. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: The average particle size of the MgO nanoparticles is 50-100 nm; the average particle size of the CaCO3 nanoparticles is 20-50 nm.

4. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: The primary pyrolysis step includes: heating from room temperature to 260-300°C at 2°C / min, then heating to 750-800°C at 5°C / min, and keeping warm for 2-3 hours; wherein, when the temperature is raised to 400-500°C, a mixed gas of CH4 and N2 with a volume ratio of 5-10:90-95 is introduced and maintained for 30-40 minutes.

5. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: After the primary pyrolysis is completed, pure N2 is purged at 750-800°C for 30-40 minutes.

6. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: The mass ratio of the carbonized product to the KOH particles is 1:1.5-1:2.

5.

7. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: The secondary pyrolysis step includes: heating to 700-750° C. at 5° C. / min under a N 2 atmosphere and keeping the temperature for 60-90 minutes.

8. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: The soaking time of the NaOH solution is 10-12 hours, and the temperature is 75-85°C; the soaking time of the citric acid solution is 6-8 hours, and the temperature is 55-65°C.

9. The negative electrode material for an energy storage lead-carbon battery according to claim 2, characterized in that: The in-situ reduction step comprises: heating the temperature to 250-350° C. at 3° C. / min in an N 2 / H 2 atmosphere with a volume ratio of 90-95:5-10, and keeping the temperature for 1-2 hours.

10. The method for preparing the negative electrode material for energy storage lead-carbon battery according to any one of claims 1 to 9, characterized in that the steps include: Lignin sulfonate, humic acid, barium sulfate, conductive carbon black, and a biomass-derived lead-carbon composite skeleton are first mixed and mechanically stirred to obtain a uniformly dispersed powder; the above powder is added to lead powder and mechanically stirred to obtain a uniformly dispersed mixture; the above mixture is placed in a paste mixer, water is added, and continuous stirring is performed until the density reaches 4.1-4.5 g / mL to obtain a uniformly mixed lead paste; the lead paste is evenly applied to the grid until the lead paste fills the through holes on the metal lead grid, and the lead-carbon battery negative electrode material is obtained after curing and drying.

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