Preparation method of lead-acid battery electrolyte with low internal resistance and long service life

Abstract

The invention discloses a preparation method of a lead-acid battery electrolyte with low internal resistance and long service life, and relates to the technical field of electrolytes. The electrolyte is composed of a sulfuric acid, phosphoric acid, boric acid and methanesulfonic acid composite acid system matched with aluminum sulfate, lithium sulfate, magnesium sulfate, sodium sulfate, sodium silicate, Na2EDTA and carboxylated carbon colloid. The pH is regulated and controlled through multi-stage buffering, a pole plate is protected by a double-layer passive film, and an electron-proton rapid channel is constructed by nanocarbon colloid-multi-salt, so that high conductivity, low ohmic impedance and excellent thermal stability are kept in a range of-20 DEG C to 60 DEG C. The preparation process adopts ultrasonic dispersion and slow dropwise addition viscosity control technologies to ensure clarification and uniformity of the electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytes, and in particular to a method for preparing a low-internal-resistance and long-life lead-acid battery electrolyte. Background Art

[0002] Existing lead-acid batteries generally use approximately 37wt% sulfuric acid as the sole electrolyte. Although this system has high conductivity, it has the following drawbacks: internal resistance and low-temperature performance: pure sulfuric acid significantly increases viscosity and begins to precipitate ice at around -10°C, and almost loses fluidity at -20°C, resulting in severe polarization and insufficient starting current; ohmic impedance is greatly affected by temperature fluctuations, making it difficult to meet the requirements of cold regions or high-power applications. Acid stratification and pH drift: H is generated or consumed during charging and discharging. + The acidity changes suddenly in the area adjacent to the plate, and the high density of sulfuric acid makes it easy for upper and lower stratification to occur when left standing, resulting in poor acidity in the upper part and excessive acidity in the lower part, which in turn accelerates the coarsening and deactivation of PbSO4. Hydrogen evolution and alloy corrosion: The negative electrode has a low overpotential and a strong hydrogen evolution side reaction, which not only consumes electrolyte and water, but also coarsens the plate alloy grains. The positive electrode has a low oxygen evolution threshold at high SOC, resulting in severe grid corrosion and limited cycle life. Coarse PbSO4 grains: Due to the lack of effective nucleation-complexation regulation, the discharge product PbSO4 agglomerates in the form of several microns to more than ten microns, making it difficult to completely reduce during charging. Residual lead sulfate causes capacity reduction. Summary of the Invention

[0003] To overcome the above-mentioned defects of the prior art, the present invention provides the following technical solution: a low internal resistance and long life lead-acid battery electrolyte, the electrolyte being in a clear and fluid state at 25°C, comprising the following components, calculated by mass fraction or molar fraction: sulfuric acid, prepared to a final solution specific gravity of 1.24–1.30 g·cm -3 , used to provide SO4 required for the reversible reaction of Pb / PbSO4 2- Phosphoric acid 0.2–0.5 wt% forms a Pb3(PO4)2 passivation film on the cathode surface to increase the oxygen evolution potential; Boric acid 2.5–5.0 g·L -1 , inhibiting hydrogen evolution at the negative electrode and slowing down lead alloy corrosion through weak acid buffering; methanesulfonic acid, 5–10 mol% based on sulfuric acid, lowers the freezing point and maintains viscosity ≤ 5 mPa·s at –20°C; aluminum sulfate 0.005–0.020 mol·L -1 , refine PbSO4 grains and build conductive chains with carbon colloids; lithium sulfate 0.020–0.100 mol·L -1 , improve low temperature receptivity and ion mobility; magnesium sulfate 0.010–0.050 mol·L -1 , synergistically stabilize the active material lattice; sodium silicate 0.05–0.20wt%, reacts with phosphoric acid to form a SiO2-phosphate double-layer passivation film on the plate surface; Na2EDTA≤0.010mol·L-1 , complexed Pb 2+ To accelerate the dissolution and recrystallization of PbSO4; carboxylated carbon colloid 0.05–0.30wt%, average particle size 50–150nm, ζ potential ≤–30mV, 25–35kHz ultrasound for 30min to form a three-dimensional suspended conductive network; the balance is deionized water.

[0004] Preferably, the total acidity of the multi-stage acid system corresponds to a pH of -0.2 to 0.0 at 25°C, and has a pH of ≥1.5 mmol H + mL -1 The buffer capacity is sufficient to ensure that the acid concentration fluctuation does not exceed ±5%.

[0005] Preferably, the carboxylated carbon colloid, aluminum sulfate and lithium sulfate cooperate to construct a continuous electron-proton channel, so that the conductivity is ≥0.70S·cm at 25°C. -1 The ohmic internal resistance is reduced by 20–35% compared with traditional 37wt% H2SO4.

[0006] Preferably, the synergistic effect of boric acid and Na2EDTA controls the average PbSO4 grain size to 0.8–1.2µm under 80% depth of discharge conditions, and completes ≥90% PbSO4-Pb conversion in the 50% SOC region at 1C charging.

[0007] Preferably, sodium silicate is hydrolyzed at pH 0.2 to 0.0 to generate a specific surface area ≥ 200m 2 ·g -1 SiO2 gel, and combined with phosphate to form a double-layer passivation film with a thickness of 10-50nm, the passivation film has a coverage of ≥95% after standing at 60℃±2℃ for 500h; further comprising 0.02-0.10molL -1 Sodium sulfate (Na2SO4) is added to improve ion mobility and help inhibit acid stratification.

[0008] Preferably, the composite acid-polysalt-carbon colloid synergistically keeps the electrolyte fluid at -20°C and the conductivity ≥0.30S·cm -1 , evaporation water loss rate at 60℃≤2wt%·500h -1 , high frequency ohmic impedance <2.0mΩ·cm 2 .

[0009] A method for preparing a low internal resistance and long life lead-acid battery electrolyte comprises the following steps: S1, diluting industrial concentrated sulfuric acid to a specific gravity of 1.24-1.30 g·cm -3, control the temperature at 20±2℃; S2, add phosphoric acid and boric acid in sequence until dissolved, and then add methanesulfonic acid; S3, dissolve aluminum sulfate, lithium sulfate, and magnesium sulfate in sequence under stirring at 300-500rpm; S4, add Na2EDTA and Na2SiO3 diluent, and monitor the viscosity online to ≤3mPa·s; S5, slowly add carboxylated carbon colloidal dispersion, and simultaneously ultrasonicate at 25-35kHz for 30min; S6, test the specific gravity, conductivity, and pH after filtering through a 0.45µm microporous membrane, and store after passing the test.

[0010] Preferably, the dripping rate of Na2SiO3 in step S4 is controlled at 0.5–1.0 mL·min -1 ·L -1 , ensuring that the viscosity increase of the system is ≤0.5 mPa·s; in step S5, the solid content of the carboxylated carbon colloidal dispersion is 5–10 wt %, and 0.05–0.10 wt % of sodium lignin sulfonate is used as a dispersant.

[0011] Compared with the prior art, the present invention has the following advantages: (1) The composite acid system of the present invention adopts a three-stage design of strong acid-weak acid-buffered acid, and cooperates with multivalent sulfates such as lithium sulfate and sodium sulfate and carboxylated carbon colloid to construct a continuous electron-proton channel, so that the conductivity at 25°C reaches 0.70S·cm -1 The above results show that the ohmic internal resistance is reduced by 20–35% compared with the traditional 37wt% sulfuric acid system. At -20°C, methanesulfonic acid and lithium salts jointly lower the freezing point and maintain a viscosity of ≤5mPa·s, achieving a viscosity of ≥0.30S·cm -1 Low-temperature conductivity ensures stable startup and charging efficiency in cold environments; (2) The specific surface area of ​​the Pb3(PO4)2 film generated by the phosphoric acid on the positive electrode surface and the hydrolysis of sodium silicate is ≥200m 2 ·g -1 SiO2 gel combines to form a 10-50nm thick composite passivation layer, with a coverage rate of ≥95% after standing at 60℃ for 500h, and the positive electrode oxygen evolution potential is increased by about 80mV; the boric acid-weak acid buffer system significantly inhibits hydrogen evolution on the negative electrode side, and cooperates with magnesium sulfate to stabilize the alloy lattice, so that the mass loss rate of the positive and negative electrodes is reduced compared with the traditional formula, and the cyclic corrosion decay rate is reduced every thousand cycles; (3) the aluminum salt of the present invention induces fine crystals, carboxylated carbon colloids provide nano-scale nucleation sites, and boric acid-Na2EDTA complexation jointly controls the average particle size of PbSO4 to 0.8-1.2µm; (4) the composite acid-weak acid system of the present invention provides pH-0.2 to 0.0 at 25℃, and a buffer capacity of ≥1.5mmolH + mL -1 Stability in a wide temperature range; Dynamic release / absorption of H by carbon colloid-weak acid groups +Function and density complement each other to eliminate static acid stratification. The acid concentration fluctuation during charge and discharge is ≤±5%, avoiding local plate deactivation caused by acid deficiency at the top and excessive acid at the bottom, and improving the consistency of high-rate output. (5) The methanesulfonic acid and boric acid of the present invention increase the high-temperature volatilization barrier, and the composite passivation film reduces the plate oxidation catalytic sites. Under the conditions of 60℃ circulation or storage for 500h, the electrolyte water loss rate is ≤2wt%·500h -1 , high frequency ohmic impedance increase <2.0mΩ·cm 2 , 2C continuous discharge temperature rise is less than 15 ° C, avoiding thermal runaway and significantly extending high temperature service life; (6) The average particle size of the carboxylated carbon colloid of the present invention is 50-150nm, the ζ potential is ≤-30mV, and a three-dimensional suspended network is constructed by 25-35kHz ultrasound; during charging, the carbon particles can reversibly adsorb and dissociate Pb 2+ With H + An "electron + proton highway" is formed. When the local conductive chain is broken due to dendrites or precipitation, the carbon colloid self-migrates to repair the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a flow chart for preparing the electrolyte of the present invention.

[0013] In the picture: Sulfuric acid dilution / temperature control unit: Concentrated sulfuric acid is added to the high-speed shearing device via a metering pump and mixed with deionized water to the target specific gravity, while maintaining the temperature at 20±2°C through a jacket or plate heat exchanger; Auxiliary acid metering unit: two-way quantitative pumps are used to continuously add phosphoric acid and boric acid solutions, and PLC performs closed-loop control according to the formula ratio; Methanesulfonic acid micro-dropping unit: flow rate 0.1–0.5 Lh -1 Precision pump to ensure a mole fraction of 5–10 mol; Inorganic salt dissolution zone: Three spiral weighing hoppers add Al2(SO4)3, Li2SO4, and MgSO4 in sequence, and stir at 300–500 rpm until completely clarified; Complexation-corrosion inhibitor addition unit: Na2EDTA solution is added once; Na2SiO3 dilution solution is added by a drip pump at 0.5–1.0 mL / min -1 L -1 , real-time feedback from viscosity probe; Carboxylated carbon colloid dispersion tank: carbon black solid content 5-10wt%, particle size 50-150nm; first ultrasonic emulsification and then dropwise addition to the main kettle via a bottom micro pump; Ultrasonic dispersion module: online tubular ultrasonicator 25–35 kHz, power 600–800 W, ensuring that the carbon particle zeta potential is ≤–30 mV; Online detection module: temperature-compensated conductivity meter, rotational viscometer, and laser particle size analyzer are linked together to automatically alarm and suspend feeding when the threshold is exceeded; Precision filtration unit: Acid-resistant PVDF filter element 0.45µm, removes agglomerates or dust particles to ensure the clarity of the electrolyte; Quality re-inspection, filling and storage: The specific gravity, conductivity and pH are re-tested in the laboratory; after passing the test, the product is vacuum-filled in acid-resistant composite barrels, and the top buffer valve is set to 30±5kPa to complete the product packaging. DETAILED DESCRIPTION

[0014] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0015] The present invention provides a low internal resistance and long life lead-acid battery electrolyte. The electrolyte is in a clear and fluid state at 25°C and comprises the following components, calculated by mass fraction or molar fraction: sulfuric acid, prepared to a final solution specific gravity of 1.24-1.30 g·cm -3 , used to provide SO4 required for the reversible reaction of Pb / PbSO4 2- Phosphoric acid 0.2–0.5 wt% forms a Pb3(PO4)2 passivation film on the cathode surface to increase the oxygen evolution potential; Boric acid 2.5–5.0 g·L -1 , inhibiting hydrogen evolution at the negative electrode and slowing down lead alloy corrosion through weak acid buffering; methanesulfonic acid, 5–10 mol% based on sulfuric acid, lowers the freezing point and maintains viscosity ≤ 5 mPa·s at –20°C; aluminum sulfate 0.005–0.020 mol·L -1 , refine PbSO4 grains and build conductive chains with carbon colloids; lithium sulfate 0.020–0.100 mol·L -1 , improve low temperature receptivity and ion mobility; magnesium sulfate 0.010–0.050 mol·L -1 , synergistically stabilize the active material lattice; sodium silicate 0.05–0.20wt%, reacts with phosphoric acid to form a SiO2-phosphate double-layer passivation film on the surface of the plate; Na2EDTA≤0.010mol·L -1 , complexed Pb 2+ To accelerate the dissolution and recrystallization of PbSO4, a 0.05–0.30 wt% carboxylated carbon colloid with an average particle size of 50–150 nm and a zeta potential of ≤–30 mV was subjected to 25–35 kHz ultrasound for 30 minutes to form a three-dimensional suspended conductive network. The balance was deionized water. The total acidity of the multi-stage acid system corresponds to a pH of –0.2 to 0.0 at 25°C and a pH of ≥1.5 mmol / L in the –20°C to 60°C temperature range. + mL -1 The buffer capacity of the acid concentration is kept within ±5%. The carboxylated carbon colloid, aluminum sulfate and lithium sulfate synergistically construct a continuous electron-proton channel, making the conductivity ≥0.70S·cm at 25℃.-1 The ohmic internal resistance is reduced by 20-35% compared to the traditional 37wt% H2SO4. The synergistic effect of boric acid and Na2EDTA controls the average size of PbSO4 grains to 0.8-1.2µm under 80% deep discharge conditions, and completes ≥90% PbSO4-Pb conversion in the 50% SOC region of 1C charging. Sodium silicate is hydrolyzed under pH-0.2-0.0 to generate a surface area of ​​≥200m 2 ·g -1 SiO2 gel, and combined with phosphate to form a double-layer passivation film with a thickness of 10-50nm, the passivation film has a coverage of ≥95% after standing at 60℃±2℃ for 500h; further comprising 0.02-0.10molL -1 Sodium sulfate (Na2SO4) is added to improve ion mobility and help inhibit acid stratification. The composite acid-polysalt-carbon colloid synergistically keeps the electrolyte fluid at -20°C and has a conductivity of ≥0.30S·cm -1 , evaporation water loss rate at 60℃≤2wt%·500h -1 , high frequency ohmic impedance <2.0mΩ·cm 2 .

[0016] Combining sulfuric acid (H2SO4) with a variety of auxiliary acids allows for multi-stage optimization of electrolyte acidity. Sulfuric acid, a strong base acid, provides key ion concentration and electrochemical activity. Phosphoric acid (H3PO4) forms a phosphate film on the plate surface, increasing the oxygen evolution potential and inhibiting cathode corrosion, thereby extending cycle life. Boric acid (H3BO3, approximately 2.5–5 g / L), a weak acid additive, significantly inhibits hydrogen evolution at the anode and stabilizes electrolyte concentration. Furthermore, small amounts of strong organic acids (such as methanesulfonic acid, CH3SO3H) can be added to further lower the freezing point and enhance conductivity. Alternatively, trace amounts of organic acids (such as oxalic acid and citric acid) can be added as auxiliary acids to form multi-stage pH buffering and generate passivation products on the plate surface. This composite acid system achieves sustained, stable acidity and high electrochemical activity through the synergistic effects of strong acid providing activity, buffering acid regulating pH, and weak acid suppressing side reactions.

[0017] Sulfuric acid H2SO4: High concentration base acid, provides the main conductivity and active species.

[0018] Phosphoric acid H3PO4: buffer, forms a Pb3(PO4)2 protective layer, and increases the positive electrode oxygen evolution threshold.

[0019] Boric acid H3BO3 (2.5–5 g / L): A weak acid that inhibits hydrogen evolution at the negative electrode and reduces grid corrosion.

[0020] Organic acid (such as CH3SO3H): Adding a small amount can further lower the freezing point and enhance high temperature stability.

[0021] The multi-acid synergistic system always provides sufficient acid concentration and buffering capacity during the battery charging and discharging process, which helps to refine the PbSO4 grains, increase the reaction rate, and inhibit the excessive dissolution and hydrogen evolution of electrode active materials.

[0022] A variety of common industrial additives are selected to achieve the synergy of multiple functions such as corrosion resistance, sulfation resistance and improved conductivity: Aluminum salts and alkali metal sulfates: Adding a small amount of aluminum sulfate (Al2(SO4)3) can significantly inhibit the deposition of PbSO4 during high-rate charge and discharge, and reduce the internal resistance of the plate; in addition, Al2(SO4)3 can also effectively repair aging batteries and improve recovery capabilities. The combined addition of salts such as lithium sulfate (Li2SO4), sodium sulfate (Na2SO4), and magnesium sulfate (MgSO4) can increase the total salt concentration and the number of ions in the electrolyte, thereby increasing conductivity and limiting the growth of lead dendrites. Complexing agents / organic additives: Industrial-grade Na2EDTA, citric acid and other complexing agents are selected to complex the Pb generated by discharge. 2+ , accelerating the dissolution of PbSO4; using surfactants such as alkyl sulfonates (such as sodium dodecyl sulfate SDS) can disperse the precipitated PbSO4 grains and form a uniform film, thereby reducing polarization and extending the cycle life. Corrosion inhibitors: introducing sodium silicate (Na2SiO3) silicate to form a dense SiO2 passivation layer on the surface of the plate, significantly slowing down the corrosion of the positive and negative lead alloys; trace amounts of Ca 2+ / Sr 2+ Divalent metal ions such as CaSO4 / SrSO4 can form CaSO4 / SrSO4 precipitates, which also help capture sulfate ions and play a slow-release role. Functionalized microparticles: Surface-functionalized (carboxyl / hydroxyl) carbon nanoparticles or carbon colloids are dispersed into the electrolyte. These microparticles provide an additional conductive network and specific surface area. The oxygen functional groups on the surface of the carbon particles can adsorb / release protons during charging and discharging, achieving local buffering, and at the same time serve as a tiny nucleation substrate for PbSO4, improving the reversibility of lead sulfate. The above additives work together: aluminum salts, multivalent sulfates and microparticles form multiple conductivity pathways; complexing agents and surfactants jointly inhibit the coarsening of lead sulfate particles; silicates and alkaline earth ions synergistically construct a stable protective film.

[0023] A multi-level microstructure is constructed within the electrolyte to optimize ionospheric distribution and buffering function: A micro-suspended phase: Surface-modified nanocarbon particles or nano-SiO2 particles are suspended in the electrolyte to form a uniformly dispersed microporous / microcavity structure. This suspended phase acts as an additional active interface, significantly increasing the contact area between the electrolyte and the plates and providing secondary transport pathways for protons and lead ions. The –COOH / –C–OH groups on the carbon colloid surface also enhance adsorption on the electrode surface and catalyze the conversion of PbSO4. Physical sedimentation or high-speed shearing maintains these particles in suspension, ensuring uniform distribution of electrolyte components throughout the entire cell height. Multi-component density matching: The ratio of light and heavy components in the electrolyte is regulated to compensate for their density differences. For example, adding a high-density Al2(SO4)3 / MgSO4 solution increases the specific gravity of the lower electrolyte layer, while an organic buffer acid can be added to the upper layer to reduce its density, achieving near-complementary stratification. This reduces acid stratification during static storage, avoiding a situation where the top layer is acidic and the bottom layer is acidic. Dynamic buffer distribution: Utilize the components of different acid strengths in the composite acid system and the acid groups on the surface of the suspended particles to achieve dynamic regulation of local pH. + (Acidity increases), weak acids such as H3PO3 and H3BO3 immediately partially dissociate and absorb H + , buffer acidity rises; when charging, H + Depletion, weak acid and carboxyl groups on the particles release H + , replenishing acidity. The acidity on the positive and negative electrode surfaces remains relatively stable, preventing excessive polarization and localized sulfate oversaturation, and suppressing uneven polarization and excessive crystal growth. The hierarchical structure design enables adaptive buffering within the electrolyte, improving the overall system's tolerance to temperature and current fluctuations.

[0024] A method for preparing a low internal resistance and long life lead-acid battery electrolyte comprises the following steps: S1, diluting industrial concentrated sulfuric acid to a specific gravity of 1.24-1.30 g·cm -3 , control the temperature at 20±2℃ (dissolve auxiliary acids such as phosphoric acid and boric acid in sequence under stirring to ensure full and uniform dissolution); S2, add phosphoric acid and boric acid in sequence until dissolved, and then add methanesulfonic acid; S3, dissolve aluminum sulfate, lithium sulfate, and magnesium sulfate in sequence under stirring at 300–500rpm; S4, add Na2EDTA and Na2SiO3 diluent, and monitor the viscosity online ≤3mPa·s (stir until transparent and free of impurities); S5, slowly add carboxylated carbon colloidal dispersion, and ultrasonicate at 25–35kHz for 30min; S6, filter through a 0.45µm microporous membrane, test the specific gravity, conductivity, and pH, and store after passing the test. The drop rate of Na2SiO3 in step S4 is controlled at 0.5–1.0mL·min -1 ·L -1, ensuring that the viscosity increase of the system is ≤0.5 mPa·s; in step S5, the solid content of the carboxylated carbon colloidal dispersion is 5–10 wt %, and 0.05–0.10 wt % of sodium lignin sulfonate is used as a dispersant.

Claims

1. A low internal resistance and long life lead-acid battery electrolyte, characterized in that: The electrolyte is in a clear and flowing state at 25°C and contains the following components, calculated by mass fraction or amount of substance: Sulfuric acid, adjusted to a final solution density of 1.24–1.30 g·cm -3 , used to provide SO4 required for the reversible reaction of Pb / PbSO4 2- ; Phosphoric acid 0.2–0.5 wt% forms a Pb3(PO4)2 passivation film on the cathode surface to increase the oxygen evolution potential; Boric acid 2.5–5.0 g·L -1 , inhibiting hydrogen evolution at the negative electrode and slowing down lead alloy corrosion through weak acid buffering; Methanesulfonic acid, 5–10 mol% calculated as sulfuric acid, depresses the freezing point and maintains viscosity ≤ 5 mPa·s at –20°C; Aluminum sulfate 0.005–0.020 mol·L -1 , refine PbSO4 grains and build conductive chains with carbon colloids; Lithium sulfate 0.020–0.100 mol·L -1 , improve low temperature receptivity and ion mobility; Magnesium sulfate 0.010–0.050 mol·L -1 , synergistically stabilize the active substance lattice; Sodium silicate 0.05–0.20wt% reacts with phosphoric acid to form a SiO2–phosphate double-layer passivation film on the plate surface; Na2EDTA≤0.010mol·L -1 , complexed Pb 2+ To accelerate the dissolution and recrystallization of PbSO4; Carboxylated carbon colloids (0.05–0.30 wt %, average particle size 50–150 nm, zeta potential ≤ –30 mV) were subjected to 25–35 kHz ultrasound for 30 min to form a three-dimensional suspended conductive network. The balance was deionized water.

2. The low internal resistance and long life lead-acid battery electrolyte according to claim 1, characterized in that: The total acidity of the multi-stage acid system corresponds to pH -0.2 to 0.0 at 25 ° C, and has ≥1.5mmolH + mL -1 The buffer capacity is sufficient to ensure that the acid concentration fluctuation does not exceed ±5%.

3. The low internal resistance and long life lead-acid battery electrolyte according to claim 1, characterized in that: Carboxylated carbon colloid, aluminum sulfate, and lithium sulfate synergistically construct a continuous electron-proton channel, resulting in a conductivity of ≥0.70 S·cm at 25°C. -1 The ohmic internal resistance is reduced by 20–35% compared with traditional 37wt% H2SO4.

4. The low internal resistance and long life lead-acid battery electrolyte according to claim 1, characterized in that: The synergistic effect of boric acid and Na2EDTA controls the average PbSO4 grain size to 0.8–1.2µm under 80% depth of discharge conditions, and completes ≥90% PbSO4-Pb conversion in the 50% SOC region of 1C charging.

5. The low internal resistance and long life lead-acid battery electrolyte according to claim 1, characterized in that: Sodium silicate is hydrolyzed under pH 0.2 to 0.0 to generate a specific surface area of ​​200m 2 ·g -1 The SiO2 gel is combined with phosphate to form a double-layer passivation film with a thickness of 10-50nm. The coverage of the passivation film is ≥95% after being placed at 60℃±2℃ for 500h. Also contains 0.02–0.10 mol / L -1 of sodium sulfate to improve ion mobility and help inhibit acid stratification.

6. The low internal resistance and long life lead-acid battery electrolyte according to claim 1, characterized in that: The composite acid-polysalt-carbon colloid synergistically maintains the electrolyte fluidity at -20°C with a conductivity of ≥0.30 S·cm -1 , evaporation water loss rate at 60℃≤2wt%·500h -1 , high frequency ohmic impedance <2.0mΩ·cm 2 .

7. A method for preparing the low internal resistance and long life lead-acid battery electrolyte according to claim 1, characterized in that: The following steps are involved: S1. Dilute industrial concentrated sulfuric acid to a specific gravity of 1.24–1.30 g·cm -3 , temperature controlled at 20±2℃; S2, add phosphoric acid and boric acid dropwise in sequence until dissolved, then add methanesulfonic acid dropwise; S3. Dissolve aluminum sulfate, lithium sulfate, and magnesium sulfate in sequence while stirring at 300–500 rpm; S4. Add Na2EDTA and Na2SiO3 diluent and monitor the viscosity online to ≤3mPa·s; S5, slowly add the carboxylated carbon colloidal dispersion dropwise while ultrasonicating at 25–35 kHz for 30 min; S6. After filtering through a 0.45µm microporous membrane, test the specific gravity, conductivity and pH, and store after passing the test.

8. The method for preparing a low internal resistance and long life lead-acid battery electrolyte according to claim 7, characterized in that: The addition rate of Na2SiO3 in step S4 was controlled at 0.5–1.0 mL min -1 ·L -1 , ensuring that the viscosity increase of the system is ≤0.5 mPa·s; in step S5, the solid content of the carboxylated carbon colloidal dispersion is 5–10 wt %, and 0.05–0.10 wt % of sodium lignin sulfonate is used as a dispersant.

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