WO2011091553A1 - Method for recycling negative electrode plate of waste lead-acid power battery - Google Patents

Abstract

A method for recycling negative electrode plates of waste lead-acid power batteries: connecting each waste lead-acid battery in series; adding dilute sulfuric acid into each battery; charging the waste lead-acid batteries with regulated electrolyte with desired specific gravity in pulse charging mode to recover the battery negative electrode capacities to initial capacities partly or totally; discharging the batteries in constant current, and recording the present capacities of the negative electrode plates of the batteries; weeding out the unrecoverable negative electrode plates based on the present capacities, and classifying other negative electrode plates into several groups based on the present capacities; cutting the negative electrode plates from the bus bar of the batteries group by group and drying them; choosing matching positive electrode plates according to the present capacities of each group of negative electrode plates, and lengthening the length of the tabs of the dried negative electrode plates to accord with the length of the tabs of the positive electrode plates; preparing a complete negative plate assembly through the bus bar by burn-welding or cast-welding; then preparing a new lead-acid battery with the negative plate assembly and the positive plate assembly composed of the matching positive electrode plates. The beneficial effects of the invention are as follows: recovering the capacities of the recycled batteries, classifying the negative electrode plates in different capacities so as to conveniently choose the corresponding positive electrode plates to match the negative electrode plates, and forming batteries with reasonable design. Simultaneously, the negative electrode does not need an antioxidative treatment, thus extra waste water or spent acid does not occur in the invention.

Description

 Recycling method of waste lead-acid battery negative plate

TECHNICAL FIELD The present invention relates to an electrode for a lead-acid battery, and more particularly to the regeneration of useful components of a used battery, and more particularly to a method for recycling a waste lead-acid battery negative plate.

BACKGROUND OF THE INVENTION With the depletion of chemical energy sources such as petroleum and the intensification of the greenhouse effect, various countries have increased investment in research and industrialization of electric vehicles. Among them, the power battery is known as the "engine" of electric vehicles, and it is the most concerned. At present, it can be put into mass production, and only the lead-acid battery is acceptable at the cost. According to conservative estimates, global electric bicycle sales in the first half of 2009 were $1,501.71 million. Under normal circumstances, batteries accounted for 20% of their sales price, which means that lead-acid battery sales in the first half of 2009 were about 300.404 million yuan. However, lead-acid batteries, as power batteries for electric vehicles, have a cycle life of only one to two years. A large number of such power batteries are scrapped every year. It is well known that batteries with a cycle end of life generally have two reasons: First, the structure of the positive plate collapses, the conductivity of the positive electrode is lost, and the battery life is terminated. Second, the negative plate is sulphated, and the decrease in capacity leads to the end of battery life. The battery having the end of life as described above has no problem in the structure and conductivity of the negative electrode plate, but the availability of the active material is lowered.

 We know that lead-acid batteries have another use, which is used as a floating charging backup power source, such as a backup power source for large telecom base stations, banks, solar street lights, and the like. The main mode of life termination of lead-acid batteries for this purpose is the loss of conductivity of the grid corrosion in the plates. Then we will find that the negative plate with the end of cycle life, although the capacity has decreased, but it can still meet the life requirement for the floating charging backup power supply. The grid structure is intact, the corrosion is slight, and the spongy lead has good electrical conductivity. . Since the battery life termination modes are different for these two modes of use, we believe that it is perfectly possible to use a negative life plate of a cycle end-of-life battery to assemble a lead-acid battery for use as a float charger.

Chinese patent application CN 101286583A proposes a processing technology for recycling and recycling waste lead-acid batteries, wherein the lead-acid battery after recycling is mechanically opened, the negative plate is taken out, and after being charged and reduced in a dilute sulfuric acid solution, the anti-defense The oxidant is treated and dried. The treated negative electrode plate can be used in combination with or separately with a new positive electrode plate and assembled into a battery. However, in this technical solution, the negative electrode plate needs to be taken out from the battery, placed in a chemical conversion tank, charged in a dilute sulfuric acid solution for reduction, and then washed and dried in an aqueous solution having an antioxidant. This method is similar to the lead-acid battery plate fabrication process, which consumes a large amount of water and produces waste acid and wastewater that are difficult to handle. At the same time, the plates are taken out and welded again in the formation tank, which wastes a lot of manpower. In addition, the patent does not classify the recovered batteries, but only uses the cell voltage higher than 1.0V as the standard for normal recovery of batteries. In fact, the cell voltage above 1.0V does not mean that the conductivity of the negative electrode of the battery and the grid structure are mostly intact. It is entirely possible that the battery with partial floating life is terminated. The negative grid is fully corroded and cannot be discharged normally. However, because it still has a small amount of capacity and conductivity, the open circuit voltage can still reach 1.0V or more. It is clear that a standard with a cell voltage above 1.0V is not reliable.

SUMMARY OF THE INVENTION The technical problem to be solved by the present invention is to provide a recycling method for a waste lead-acid battery negative plate by avoiding the above-mentioned deficiencies of the prior art, and solving the prior art, which consumes a large amount of water and is difficult to handle. The waste acid and waste water, and the negative classification of the negative electrode plate make the recovery performance not high. The technical problem is solved by the present invention by adopting the following technical solutions: Providing a recycling method for a waste lead-acid power battery negative plate, which comprises the following steps in sequence:

 A. The waste lead-acid batteries are connected in series, and dilute sulfuric acid having a specific gravity of 1.28 ~ 1.34 is added to each battery cell, and the added amount is 5 - 20% of the normal acid amount of the battery monomer, to observe the battery separator The top is clearly free acid; and adjust the battery electrolyte to the same 1.28 - 1.32 of the normal battery, and then set aside for 4 - 24 hours.

 B. Charging the waste lead acid battery with the adjusted specific gravity of the electrolyte to meet the requirements, and charging or replacing all of the negative electrode capacity of the battery to the original capacity value.

 C. discharging the battery at a constant current and recording the discharge amount of the negative plate. When the battery is discharged to an allowable termination voltage, the recorded negative plate discharge amount is the current capacity of the negative plate of the battery. .

D. Excluding the negative plate with the existing capacity of the negative plate lower than 70% of its original capacity, the other negative plates are divided into each capacity group with a difference of 10% of the existing capacity.

 E. Move each of the battery capacity groups into a glove box with nitrogen protection, and cut the negative plate from the bus bar of the battery.

 F. The cut negative plates are then separately transferred to a vacuum-protected vacuum oven in units of volume groups until the moisture content in the vacuum oven is no longer changed.

' G. Select the positive electrode plate with the existing capacity of each negative capacity plate of the capacity group, and lengthen the tabs of the dried negative electrode plate so that the length thereof is consistent with that of the positive electrode plate. H. The negative electrode plate elongated by the tab is formed into a complete negative electrode group by a bus bar by welding or casting, and the positive electrode formed by the positive electrode group is matched to form a new lead. Acid battery. The step B "charges the diluted electrolyte to the desired waste lead-acid battery by a pulse charging method to restore part or all of the battery negative capacity to the original capacity value", including a sub-step: bl The battery is charged at a current of 0.05 to 0.1 times the rated capacity of the battery, and the amount of charge is one to four times the rated capacity of the battery.

 B2. Discharge at a current of 0.05 - 0.1 times the rated capacity of the battery to its allowable termination voltage value. Repeat steps bl and b2 three times until the discharge time of the used lead-acid battery no longer changes significantly. Step C: "Discharge the battery at a constant current and record the discharge amount of the negative electrode. When the battery is discharged to an allowable electrical termination voltage, the recorded negative discharge amount is the negative capacitance value of the battery. ", including sub-steps:

 Cl. inserting the reference electrode into the acid-adding hole of the battery treated by the step B, or the hole drilled in the battery cover, so that the reference electrode is located in the upper part of the single-cell pole group And make it contact with the electrolyte inside the battery.

 5倍, When the tolerance is reached, the relative voltage of the reference electrode and the negative electrode plate is recorded, and then discharged at a constant current, the constant current is 0. 05 ~ 0. 5 times of the rated capacity of the battery. When the voltage condition is terminated, the capacity discharged from the negative electrode in the single cell is calculated, which is the current capacity of the negative electrode of the battery. In step F, "the negative plate that has been cut is still moved to the vacuum oven with nitrogen protection in each capacity group, until the moisture content in the vacuum oven does not change" : each of the negative plates is baked in a vacuum oven at a temperature of 40'C ~ 10 (TC), and the vacuum oven is vacuumed every 10 to 30 minutes to discharge the water in the vacuum oven until the vacuum The moisture content in the oven is no longer changed. The step of "extending the tabs of the dried negative plate to make the length coincide with the positive plate" includes the following steps:

Gl. Cut the tabs on the main body of the negative plate to make the remaining length of the tabs! ^ Meets the following formula: L, = D,

Where R. ₆ is the arc radius of the curved joint 06 of the main body of the tab and the negative plate, D, which is the reserved value of the negative electrode, generally takes 1 ~ 5 mm;

. g2 IHJ making a mold groove, the groove width of the tab ^ adapting the width W, of the tab ₄ than the groove depth H E3 H comparing thickness 0.5 - second surface; its length L ₄ is adapted to the length L to which the tab is to be lengthened;

G3. Rolling a lead block of the same material as the tab, until the thickness of the lead block is the same as the thickness of the pole, and then cutting the lead block into a lead strip, the thickness of the lead strip H ₃ The width ^ is the same as the thickness H and the width W of the tab, and the length L ₃ satisfies the following formula:

L ₃ = L - L, -D ₂ ,

Where L is the length of the main body of the negative plate to be lengthened, 1^ is the remaining length of the ear in step gl; D ₂ lead reserve value, taking l ~ 3mm;

G4. placing the tab of the negative plate into the G3 slot of the mold, and placing the lead strip into the C3 slot, so that the lead strip is in contact with the top of the G3 slot, and the tab is The gap between the lead strips is the same as the negative reserve value D ₂ ;

 G5. melting the portion where the tab and the lead are close to each other by flame heating, and then adding lead water to the gap between the two, so that the thickness at the gap is not lower than that of the tab Thickness H. The capacity of the positive electrode plate in the positive electrode plate in which the current capacity of the negative electrode plates of the respective capacity groups is selected in the step G is 90 to 95% of the existing capacity of the negative electrode plate.

 The allowable termination voltage is: 6. 8 - 5. 4V for a 6V battery and 9. 6 - 10. 8V for a 12V battery.

 The reference electrode is a cadmium electrode for bismuth or a mercury sulphate electrode. Compared with the prior art, the invention has the following advantages: the capacity recovery process is performed on the recovered battery, and the negative electrodes of different capacities are classified, and the corresponding positive electrode can be conveniently selected for matching to form a battery with reasonable design. . At the same time, in the application, the anode is not required to be subjected to an oxidation treatment, and no new wastewater or waste acid is produced.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic flow chart of a preferred embodiment of the present invention; 2 is a diagram showing the negative electrode 01 and the lead strip 03 placed in the IHJ slot mold in a preferred embodiment of the present invention.

 04 is a top view of the groove 0401;

 Figure 3 is a cross-sectional view of the A-A of Figure 2;

 Figure 4 is a cross-sectional view of B-B in Figure 2. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be further described with reference to preferred embodiments shown in the accompanying drawings.

 Referring to Figure 1, a preferred embodiment of the recycling method for the waste lead-acid battery of the present invention is as follows:

 A. The waste lead-acid batteries are connected in series, and dilute sulfuric acid having a specific gravity of 1.28 - 1.34 is added to each battery cell, and the added amount is 5 - 20% of the normal acid amount of the battery monomer, to observe the battery separator The top is clearly free acid; and adjust the battery electrolyte to the same 1.28 - 1.32 of the normal battery, and then set aside for 4 ~ 24 hours.

 B. Charging the waste lead acid battery with the adjusted specific gravity of the electrolyte to meet the requirements, and charging or replacing all of the negative electrode capacity of the battery to the original capacity value.

 C. Discharge the battery at a constant current and record the discharge amount of the negative plate. When the battery is discharged to the discharge end voltage, the recorded negative plate discharge amount is the existing capacity of the negative plate of the battery.

 D. Excluding the negative plate with the existing capacity of the negative plate lower than 70% of its original capacity, the other negative plates are divided into the respective capacity groups with a difference of 10% of the existing capacity.

 E. moving to the glove box with nitrogen protection in units of each capacity group of the battery, and cutting the negative plate from the bus bar of the battery;

 F. The cut negative plates are still separately transferred to a nitrogen-protected vacuum oven in units of volume groups until the moisture content in the vacuum oven is no longer changed.

 G. Selecting a positive electrode plate adapted to the existing capacity of the negative electrode plates of the respective capacity groups, and lengthening the tabs of the dried negative electrode plate to have the same length as that of the positive electrode plate.

H. The negative electrode plate elongated by the tabs is formed into a complete negative electrode group by a bus bar by welding or casting, and a positive electrode group composed of the positive electrode sheets is matched to form a new lead. Acid battery. The step B "charges the diluted electrolyte to the desired waste lead-acid battery by a pulse charging method to restore part or all of the battery negative capacity to the original capacity value", including a sub-step: bl Charging the battery with a current of 0.05 - 0.1 times the rated capacity of the battery, the amount of charge is the battery rating One to four times the capacity;

 B2. Discharge at a current of 0.05 - 0.1 times the rated capacity of the battery to its allowable termination voltage value. Repeat steps bl and b2 for 1~3 times until the discharge time of the used lead-acid battery no longer changes significantly. Step C: "discharge the battery at a constant current, and record the discharge amount of the negative electrode. When the battery is discharged to the discharge termination voltage, the recorded negative discharge amount, that is, the negative electrode capacity value of the battery", Including sub-steps:

 Cl. inserting the reference electrode in the acid-adding hole of the battery treated in the step B or in the hole drilled in the battery cover, so that the reference electrode is located in the upper part of the single-cell electrode group, And bringing it into contact with the electrolyte inside the battery;

 The ratio of the relative voltage of the reference electrode and the negative electrode plate is recorded, and then discharged at a constant current, which is 0. 05 - 0. 5 times, when the allowable termination is reached. In the case of a voltage condition, the capacity of the negative electrode discharged from the single cell is calculated, which is the current capacity of the negative electrode of the battery.

 The reference electrode in this example is a cadmium electrode or a mercury sulphate electrode. In step F, "the negative electrode plate is moved to a nitrogen-protected vacuum oven for baking until the moisture content in the vacuum oven is no longer changed". That is: the negative plate is at temperature 4 (The TC- ΙΟΟΧ vacuum oven was flooded and the vacuum oven was evacuated every 10-30 minutes to drain the water in the vacuum oven until the moisture content in the vacuum oven no longer changed. Referring to Figures 2 to 4, in step G, "the length of the tab of the dried negative electrode plate is lengthened to be the same as the length of the positive electrode plate", including the steps of:

 Gl. Cut the upper tab 02 of the negative plate main body 01 so that the remaining length L of the tab 02 conforms to the following formula:

L, = R ₀₆ + D„

Where R. ₆ is the arc radius of the arc joint 02 of the tab 02 and the negative plate main body 01, D, which is the reserved value of the negative pole, generally takes 1 - ⁵

G2. forming a groove mold 04, the width W _{4 of} the groove 0401 is adapted to the width W of the tab 02, The depth H _{4 of the} groove 0401 is higher than the thickness H of the tab 02 by 0.5 to 2 faces; and the length L _{4 thereof} coincides with the length L to which the tab 02 is to be elongated.

G3. Rolling the lead piece of the same material as the tab 02 until the thickness of the lead block is the same as the thickness of the tab 02, and then cutting the lead block into a lead strip 03, the lead strip 03 The thickness H ₃ and the width W ₃ are respectively the same as the thickness H and the width W of the tab 02, and the length L _{3 thereof} satisfies the following formula:

L3 ⁼ L ^— Li— Ds,

Where L is the length to which the tab 02 of the negative plate body 01 is to be lengthened, 1^ is the remaining length of the tab 02 in the step gl, and D ₂ is the reserved value of the lead strip, and takes 1 - 3 to let.

G4. The tab 02 of the negative plate main body 01 is placed in the groove 0401 of the mold 04, and the lead strip 03 is also placed in the groove 0401, so that the lead strip 03 and the groove 0401 are The top contact, and the gap 05 between the tab 02 and the lead strip 03 is the same as the lead strip reserve value D ₂ .

G5. The portion where the tab 02 and the lead block 03 are close to each other is melted by flame heating, and then lead water is added to the gap 05 between the two so that the thickness of the gap 05 is not lower than The thickness of the tab 02 is 11. The capacity of the positive electrode plate in the "positive plate with which the existing capacity of the negative electrode plate is selected" in step G is 90 - 95% of the existing capacity of the negative electrode plate, as shown in the following table:

 Since the concentration of the electrolyte has been adjusted to the same in step A of the scheme, the amount of sulfuric acid contained in each of the recovered negative plates is the same. Thus, when the battery is acidified with the same acid, the acid specific gravity of each unit cell is also the same. Therefore, it is sufficient to calculate the concentration and amount of sulfuric acid to be added in accordance with the final desired sulfuric acid concentration in combination with the amount of sulfuric acid contained in the negative electrode plate.

 The allowable termination voltages in this embodiment are: 6. 8 - 5. 4V for a 6V battery and 9. 6 ~ 10. 8V for a 12V battery. The lead-acid battery produced by the method of the present invention can be used for various purposes, such as recycling as a power battery, and using it as a floating charging backup power source. The most suitable use case is the floating charging standby power supply, which is a 2.28 - 2.3V/cell, long-term small current charging, only the mode of discharge is occasionally performed. The above-described process is a preferred implementation process of the present invention, and it is within the scope of the present invention to make the usual changes and substitutions of the present invention substantially by those skilled in the art.

Claims

 Responsibility for the recycling method of the waste lead-acid battery negative plate, including the following steps:  A. The waste lead-acid batteries are connected in series, and dilute sulfuric acid having a specific gravity of 1.28 - 1.34 is added to each battery cell, and the added amount is 5-20% of the normal acid amount of the battery cell, to observe the battery separator. The top is clearly free acid; and adjust the battery electrolyte to the same 1.28 - 1.32 of the normal battery, and then set aside for 4 - 24 hours;  B. charging the waste lead-acid battery with the adjusted electrolyte specific gravity by a pulse charging method to restore part or all of the battery negative capacity to the original capacity value;  C. discharging the battery at a constant current, and recording the discharge amount of the negative plate. When the battery is discharged to the allowable discharge termination voltage, the recorded negative plate discharge amount is the current capacity of the negative plate of the battery. ;  D. Excluding the negative electrode plate whose current capacity is lower than 70% of its original capacity, and dividing the other negative electrode plates into each capacity group with a difference of 10% of the existing capacity;  E. moving to the glove box with nitrogen protection in units of each capacity group of the battery, and cutting the negative plate from the bus bar of the battery;  F. The cut negative plate is still moved to a nitrogen-protected vacuum oven in each volume group, until the moisture content in the vacuum oven does not change;  G. selecting a positive electrode plate adapted to the existing capacity of the negative electrode plates of the respective capacity groups, and lengthening the tabs of the dried negative electrode plate to have the same length as the positive electrode plate;  H. The negative electrode plate elongated by the tab is formed into a complete negative electrode group through a bus bar by welding or casting, and a positive electrode group composed of the positive electrode plate is matched to prepare a new lead acid. battery. A recycling method for a waste lead-acid battery negative plate according to claim 1, characterized in that:  The step B "charges the waste lead-acid battery with the adjusted electrolyte specific gravity to be charged by the pulse charging method to restore part or all of the battery negative capacity to the original capacity value", including sub-steps:  Bl. charging the battery with a current of 0.05 - 0.1 times the rated capacity of the battery, the amount of charge being one to four times the rated capacity of the battery;  B2. Discharge at a current of 0.05 - 0.1 times the rated capacity of the battery to its allowable discharge termination voltage. Repeat steps bl and b2 for 1~3 times until the discharge time of the used lead-acid battery no longer changes significantly. Until now. A recycling method for a waste lead-acid battery negative plate according to claim 1, wherein:  In step C, "the battery is discharged at a constant current, and the discharge amount of the negative electrode is recorded. When the battery is discharged to an allowable discharge termination voltage, the recorded discharge amount of the negative electrode, that is, the negative electrode capacity value of the battery. ", including sub-steps:  Cl. inserting the reference electrode in the acid-adding hole of the battery treated in the step B or in the hole drilled in the battery cover, so that the reference electrode is located in the upper part of the single-cell electrode group, And bringing it into contact with the electrolyte inside the battery;  c 2. recording the relative voltages of the reference electrode and the negative plate, and then discharging at a constant current, which is 0.05 - 0.5 times the rated capacity of the battery, when the allowable termination voltage condition is reached, The capacity of the negative electrode discharged from the single cell is calculated, which is the current capacity of the negative electrode of the battery. A recycling method for a waste lead-acid battery negative plate according to claim 1, wherein:  In step F, "the negative plate that has been cut is still moved to the vacuum oven with nitrogen protection in units of empty groups until the moisture content in the vacuum oven no longer changes." Said: each of the negative plates is baked in a vacuum oven at a temperature of 40'C to 100'C, and the vacuum oven is evacuated every 10 to 30 minutes to discharge the water in the vacuum oven until the The moisture content in the vacuum oven does not change. A recycling method for a waste lead-acid battery negative plate according to claim 1, wherein:  In step G, "the length of the tab of the dried negative electrode plate is lengthened to be consistent with the positive electrode plate", including sub-steps: Gl. Cutting the upper tab (02) of the negative plate body (01) so that the remaining length L of the tab (0 ² ) conforms to the following formula:

Where R. ₆ is the radius of the arc of the arc joint (06) of the tab (02) and the main body (01) of the negative plate, and ^ is the reserved value of the negative electrode, generally taking 1 - ⁵ legs. G2. Making a groove mold (04), the width W _{4 of} the groove (0401) is adapted to the width (W) of the tab (0401), and the depth H _{4 of} the groove (0401) is larger than the tab ( 02〜2腿; Its thickness H is higher than 0. 5 ~ 2 legs; The length 1^ ₄ coincides with the length L to which the tab (02) is to be lengthened. G3. Rolling the lead piece of the same material as the tab (02) until the thickness of the lead block is the same as the thickness of the tab (02), and then cutting the lead block into a lead strip (03) The thickness H ₃ and the width W _{3 of} the lead strip (03) are respectively the same as the thickness H and the width W of the tab (02), and the length L _{3 thereof} satisfies the following formula:

Where L is the length to which the tab (01) of the negative plate body (01) is to be lengthened, which is the remaining length of the tab (02) in step gl, and D ₂ is the reserved value of the lead strip, taking 1-3 G4. Put the tab (02) of the negative plate main body (01) into the groove (0401) of the mold (04), and place the lead strip (03) into the groove (0401). In the middle, the lead strip (03) is brought into contact with the top of the groove (0401), and the gap (05) between the tab (02) and the lead strip (03) and the lead strip reserve value D ₂ the same;  G5. The portion where the tab (02) and the lead block (03) are close to each other is melted by flame heating, and then lead water is added to the gap (05) between the two to make the gap (05). a thickness at which the thickness of the tab (02) is not less than H. The recycling method of the waste lead-acid battery negative plate according to claim 1, characterized in that:  The capacity of the positive electrode plate in the positive electrode plate in which the current capacity of the negative electrode plates of the respective capacity groups is selected in step G is 90 to 95% of the existing capacity of each negative electrode plate according to claim 12 or The recycling method of the waste lead-acid battery negative plate is characterized in that: the allowable termination voltage: 4.8-5.4V for a 6V battery, 9.6~10.8V for a 12V battery, and waste lead acid according to claim 3. A method for recycling a negative electrode plate of a power battery, characterized in that:  The reference electrode uses a cadmium electrode or a mercury sulphate electrode.