22 Years' Battery Customization

You must understand the principle and process of lithium ion battery

Feb 14, 2019   Pageview:1018

China energy storage News: Lithium ion batteries is a kind of secondary battery(rechargeable batteries). It mainly relies on Li + embedded back and forth between the two electrodes and embedded off to work. Downstream industry development, such as energy car lithium-ion battery production scale is expanding.

This topic is divided into upper and lower two parts, the last focuses on the principle of lithium ion battery, formulation and technological process. The next lecture lithium battery production and performance, this paper this topic last.

A, work principle

1, the anode structure

LiCoO2 (PVDF) + + conductive agent, binder set fluid (aluminum foil)

2, the cathode structure

Graphite + conductive agent, thickening agent (CMC) + binder (SBR) + fluid (copper foil)

3, the working principle of

3.1 the charging process

A power supply to recharge the battery, the positive on the electronic e running on the cathode through an external circuit is lithium ion Li + "jump" from the positive electrolyte, "climb" diaphragm winding holes, "swimming" arrived at the cathode, and would have run to come over together. At this time:

On a positive response to:

On a negative response is:

3.2 the battery discharge process

Electric discharge has permanently exile and constant resistance discharge, electricity is actually in the external circuit with a constant exile can changes over voltage variable resistance, constant resistance discharge is of the essence of the battery is negative and a resistor through electronic. Therefore, as long as the cathode electron can't run away from the cathode to the anode, the battery will not discharge. Electronic and Li + is action at the same time, in the same direction is different, but the road is discharging, electrons from the cathode through electronic conductor ran to the anode, lithium ion Li + from the cathode "jump" in the electrolyte, "climb" diaphragm winding holes, "swimming" to the anode, and would have run to come over together.

3.3 charge and discharge characteristics

Batteries anode used LiCoO2, LiNiO2, LiMn2O2, of which the LiCoO2 is a very stable crystal layer structure, but when away from LiCoO2 x Li ion, its structure may change, but whether to change depends on the size of the x.

Through the study found that when x > 0.5, Li1 - xCoO2 structure is extremely unstable, can produce crystal structure collapsed, its external performance for batteries over end. So the batteries in use process should be through the limit of the charging voltage to control the Li1 - xCoO2 x value, average charging voltage isn't as less than 0.5 x is greater than 4.2 V, then Li1 - xCoO2 crystal structure is still stable.

Negative C6 itself has its own characteristics, when the first time into the positive Li of LiCoO2 is filled to negative C6, when Li returned to the anode discharge LiCoO2, but after into there must be a part of Li at the cathode C6 center, to ensure the normal embedding of charge-discharge Li next time, otherwise the batteries over a short, in order to ensure that there is a part of Li in anode C6, generally by limiting the discharge threshold voltage to achieve: safe maximum charge voltage of 4.2 V or less, discharge threshold voltage is 2.5 V or higher.

The principle is the crystallization of memory effect, in lithium electricity almost won't produce this kind of reaction in the pool. However, lithium ion battery in the many falls and put the filling capacity will still be the reason for this is complex and diverse. Mainly is the change of the anode materials itself, from the molecular level, is the cathode for lithium ion hole structure will gradually collapse, congestion; From the chemical point of view, is anode materials are active passivation, appear side effects to generate stable other compounds. Physically there will be the anode material gradually spalling, etc., in short eventually reduce the battery is free to move in the process of charging and discharging lithium ion number.

Overcharge and over discharge, across the electrodes for lithium ion batteries cause permanent damage to the molecular level, can be intuitive understanding, anode carbon discharge will cause excessive release of lithium ion and its layer structure appeared to collapse, excessive charging will take too much lithium ion shoehorned into the structure of cathode carbon, and makes some of the lithium ion can no longer be released.

Unsuitable temperature will trigger a lithium ion battery internal chemical reaction to generate we don't want to see other compounds, so in many of the lithium ion battery is between the cathode is equipped with protective temperature control diaphragm or electrolyte additives. Under the condition of the battery heating up to a certain, composite membrane film hole closed or electrolyte degeneration, battery internal resistance increases until the cut-off, battery is no longer to heat up, make sure the battery temperature is normal.

Second, the formulation and technological process of lithium-ion batteries

1. Is the cathode formula

1.1 the positive formula: LiCoO2 + conductive agent, binder + set fluid (aluminum foil)

LiCoO2 (10 microns) : 96.0%

Conductive agent (CarbonECP) 2.0%

Adhesive (PVDF761) 2.0%

NMP (increase) bonding: the weight of the solid matter than about 810, 1496

A) the positive 6000 CPS viscosity control (3) temperature 25 rotor;

B) NMP weight should be appropriate adjustment, it is advisable to meet the requirements of viscosity;

C) pay special attention to the influence of temperature and humidity on the viscosity

The positive active material:

Cobalt acid lithium: the positive active material, lithium ion source, the source for lithium battery increase. Nonpolar substances, irregular shape, particle size D50 generally for 6 to 8 microns, water content of 0.2% or less, usually in the form of alkali, pH value of around 10-11.

Lithium manganese acid: nonpolar substances, irregular shape, particle size D50 generally for 5-7 microns, water content of 0.2% or less, usually a weak alkaline, pH value of 8 or so.

Conductive agent: catenary, water content < 1%, particle size is usually 1-5 microns. Excellent conductivity superconductivity carbon black are often used, such as the carbon black CarbonECP and ECP600JD, its role: to improve the conductivity of the anode materials, compensate for the positive active material electronic conductivity; Improve the positive plate of electrolyte fluid absorption quantity, increase the interface reaction, reduce the polarization.

PVDF binder: nonpolar substances, catenary, the molecular weight range from 300000 to 3000000;After absorbing water molecular weight drops, viscosity variation. Used to cobalt acid lithium, conductive material and aluminum foil or aluminum mesh together. The used brands such as Kynar761.

NMP: weak polar liquid to dissolve/swelling PVDF, used to dilute pulp at the same time.

Set fluid (the anode lead) : made from aluminum foil or aluminum tape.

Anode recipe: 1.2 + graphite conductive agent + thickening agent (CMC) + binder (SBR) + fluid (copper foil)

Anode materials (graphite) : 94.5%

Conductive agent (CarbonECP) : 1.0% (jean superconductive carbon black)

Binder (SBR) : 2.25% (SBR = styrene butadiene rubber latex)

Thickener (CMC), 2.25% sodium carboxymethyl cellulose (CMC =)

Water: the weight of the solid material ratio of 1600:1417.5

A) negative viscosity control CPS, 5000-6000 (3) temperature 25 rotor

B) water weight need appropriate adjustment, it is advisable to meet the requirements of viscosity;

C) pay special attention to the temperature humidity effect on the viscosity

2, positive and negative mixing

Graphite: the cathode active material, form the main material of cathode reaction; Mainly divided into two categories: natural graphite and artificial graphite. Nonpolar substances, vulnerable to nonpolar substances pollution, easy to disperse in nonpolar substances; Has difficulty in absorbing water, not easily dispersed in water. After the contaminated graphite dispersed in water, and is easy to reunite. Average particle diameter D50 is about 20 microns. Particle shape diverse and more irregular, mainly such as spherical, lamellar and fibrous.

Conductive agent, its function is:

A) improve the cathode piece, the conductivity of the compensation of the cathode active material electronic conductivity.

B) improve the reaction depth and utilization.

C) prevent the formation of dendrite.

D) using liquid absorbing ability of conductive materials, improve the interface reaction, reduce the polarization.(can choose with or without according to graphite particle size distribution).

Additives: reduce the irreversible reaction, improve the adhesion strength, improve the slurry viscosity, prevent pulp precipitation.

Thickener/anti precipitation agent (CMC) : high polymer compounds, soluble in water and polar solvent.

Isopropyl alcohol: weak polar material, can reduce the polarity of the glue solution after China's entry into wto, to improve the compatibility of graphite and adhesive solution; Have strong defoaming effect; Easy to catalytic adhesive mesh chain, improve the bonding strength.

Ethanol: weak polar material, can reduce the polarity of the glue solution after China's entry into wto, to improve the compatibility of graphite and adhesive solution; Have strong defoaming effect; Easy catalytic adhesive linear chain, improve the bonding strength, the effect of isopropyl alcohol and ethanol in essence is the same, when mass production, can consider cost factors and then decide which one to add).

Water-based adhesives (SBR) : using graphite and conductive agent, additives and copper foil or copper mesh together. Small molecule linear chain emulsion, easily soluble in water and polar solvents.

Deionized water or distilled water, diluent, whether to add, change the size of liquidity.

The cathode lead: made from copper foil or nickel.

2.1 the anode mixture:

2.1.1 the pretreatment of the raw material

1) cobalt acid lithium: dehydration.120 ° C atmospheric is commonly used in baking 2 hours or so.

2) conductive agent: dehydration.200 ° C atmospheric is commonly used in baking 2 hours or so.

3) adhesive: dehydration.120-140 ° C is commonly used in atmospheric bake for 2 hours, baking temperature depending on the size of the molecular weight of the decision.

4) NMP: dehydration. Using molecular sieve dehydration drying or the use of special facilities, direct use.

2.1.2 material ball mill:

1) over four hours, sieving isolated ball mill;

2) the LiCoO2 and CarbonECP pour into barrels, while adding a grinding ball grinding balls (dry: = 1:1), on the rolling cylinders and ball mill, speed control in more than 60 RMP

2.1.3 raw material with:

1) the dissolution of adhesive (according to the standard concentration) and heat treatment.

2) cobalt acid lithium and conductive material ball mill: make preliminary mixed powder, cobalt acid lithium and conductive material together, improve the function and the electrical conductivity of the reunion. Match into pulp after not separate distribution in the adhesive, ball grinding time is usually 2 hours; To avoid mixed with impurities, often use agate ball for ball mill meson.

2.1.4 powder dispersion, wet:

Principle: solid powder is placed in the air, with the passage of time, will be part of the air on the surface of the solid adsorption, liquid adhesive after joining, liquid and gas on the solid surface; If the ratio of solid and gas adsorption with liquid adsorption force strong, liquid cannot wet solid; If the solid and liquid adsorption ratio and gas adsorption force strong, solid and liquid can be soaked out gas.

When the wetting Angle 90 ° or less, solid water. When the wetting Angle > 90 °, solid not wet.

The anode material of all team members can soak glue solution, so the positive powder dispersed relatively easy.

The influence of dispersion method of dispersion:

1) incubation method (a long time, the effect is poor, but not the original structure damage material);

2) mixing method: rotation or rotation and revolution (time is short, the effect is good, but is likely to damage its structure of individual materials).

Impeller effects of dispersion speed impeller generally include serpentine, butterfly, ball, blades, gears, etc. General serpentine, butterfly, paddle type impeller is difficult to deal with scattered materials or ingredients in the initial stage; Spherical, the gear form is used to disperse the difficulty low status, the effect is better.

Stirring speed to the influence of the dispersion velocity. Generally the higher the stirring speed, the faster the scattered, but the material itself structure and the greater the damage to equipment.

The influence of concentration of dispersion rate. Normally slurry concentration is smaller, the faster the scattered, but it's too thin will cause the waste of material and pulp precipitation increase.

The influence of concentration of bond strength. Concentration, the greater the soft system, the greater the intensity, the greater the bonding strength; The lower the concentration, the smaller the bonding strength.

The influence of vacuum degree of dispersion rate. High vacuum is advantageous to the material on the surface of the gap and gas discharge, reduce the difficulty of the liquid adsorption, Material in the case of weightlessness or weaker gravity will greatly reduced the difficulty of dispersed evenly.

The influence of temperature on the dispersion rate. Good appropriate temperature, slurry flow, easy to spread. Too hot paste easy crust, too cold slurry liquidity will be discounted.

Dilution: adjust the size to the appropriate concentration, is advantageous for the coating.

2.1.5 steps

A) will combine NMP dynamic mixer (100 l) to 80 ° C, weigh and PVDF join, start; Parameter Settings: speed to 25 + 2 r/min, 115-125 minutes;

B) turn on the cooling system, will have the positive dry grinding size averaged four times, each time interval 28-32 minutes, the third time charging depending on the materials you need to add NMP, fourth NMP is joined after loading; The mixing machine parameters Settings: speed of 20 plus or minus 2 revolutions per minute

C) for the fourth time charging for high speed stirring, after 30 + 2 minutes time of 480 + 10 minutes; Dynamic mixing machine parameter Settings: revolution for 30 + 2 r/min, since to 25 + 2 r/min;

D) vacuum mixing: mix power machine connected to the vacuum, keep the vacuum degree is 0.09 Mpa, mixing 30 + 2 minutes; Dynamic mixing machine parameter Settings: revolution for 10 + 2 minutes, since to 8 + 2 revolutions per minute

E) take 250-300 - ml size, viscosity meter is used to measure the viscosity; Test conditions: the rotor number 5, 12 or 30 RPM speed, temperature range is 25 ° C;

F) extracted from the anode material dynamic mixer for colloid mill, sieving, at the same time on the stainless steel bowl with logo, and plasma equipment operators after the handover can be inflow pulp operation process.

2.1.6 matters needing attention

A) complete, clean the machine equipment and working environment;

B) the operation of the machine, need to pay attention to safety, to avoid hitting the head.

2.2 the cathode mixture

2.2.1 the pretreatment of the raw material:

1) graphite:

A, mixing, making raw material homogenizing, and improve the consistency.

Atmospheric pressure baking, B, 300 ~ 400 ° C to remove surface oily substance, improve compatibility with the water-based adhesive ability, repairing circular graphite surface edges (some materials to keep the surface features, are not allowed to baking, or poor performance).

2) water-based adhesives: appropriate dilution, improve the dispersion ability.

2.2.2 admixture, wetted and dispersed:

1) graphite and adhesive solution polarity is different, not easy to spread.

2) alcohol aqueous solution can be used first graphite initial wetting, then mixed with adhesive solution.

3) should decrease the mixing concentration, improve the dispersion.

4) the dispersion process in order to reduce the polar and nonpolar distance, improve the potential energy or surface energy, so as the endothermic reaction, the decrease in the overall temperature at the time of mixing. If conditions permit should be appropriate mixing temperature rising and makes it easy to heat, increasing liquidity at the same time, the dispersed easier.

5) mixing process, such as add vacuum degassing process, eliminate gas, promote the solid-liquid adsorption, the effect is much better.

6) dispersion principle, dispersion method with the positive ingredients in the related content

2.2.3 dilution:

Adjust the size to the appropriate concentration, easy to coating.

2.2.4 material ball mill

1) will be negative and KetjenblackECP to VAT at the same time add ball mill (grinding balls dry: = 1:1. 2) in the roll on bottle and ball mill, speed control in more than 60 RMP;

2) over four hours, sieving isolated ball mill;

2.2.5 steps

1) pure water heated to 80 ° C in a dynamic mixer (2 l)

2) adding CMC, stir 60 + 2 minutes; The mixing machine parameters Settings: revolution is 25 + 2 minutes, since to 15 + / - 2 r/min;

3) add SBR and deionized water and stir 60 + 2 minutes;

Dynamic mixing machine parameter Settings: revolution for 30 + 2 minutes, since to 20 plus or minus 2 r/min;

4) negative dry points, four times the average in order to join, charging at the same time in pure water, 28-32 minutes every time interval; Dynamic mixing machine parameter Settings: revolution is 20 + 2 r/min, since to 15 + / - 2 r/min;

5) fourth charging for high speed stirring, after 30 + 2 minutes time of 480 + 10 minutes;

Dynamic mixing machine parameter Settings: revolution for 30 + 2 r/min, since to 25 + 2 r/min;

6) vacuum mixing: mix power machine connected to the vacuum, keep the vacuum degree is 0.09 to 0.10 Mpa, mixing 30 + 2 minutes;

Dynamic mixing machine parameter Settings: revolution for 10 + 2 minutes, since to 8 + 2 revolutions per minute

7) take 500 ml size, viscosity meter is used to measure the viscosity;

The test conditions: rotor number 5, 30 RPM speed, temperature range is 25 ° C;

8) will be the cathode materials extracted from the dynamic mixing machine for grinding and sieving, at the same time on the stainless steel bowl with logo, and plasma equipment operators after the handover can be inflow pulp operation process.

2.2.6 matters needing attention

1) complete, cleaning machinery and equipment and working environment;

2) when operating the machine, need to pay attention to safety, to avoid hitting the head.

Ingredients to note:

Avoid mixed with other impurities;

To prevent slurry spray;

The concentration of the slurry (solids) from high to low gradually adjusted, so as not to increase the trouble;

Pay attention to in the process of mixing of intermittent scraping sides and a bottom, to ensure uniform dispersion;

Size should not be shelved for a long time, in order to prevent precipitation or uniformity;

After baking materials must be sealed cooling can join, lest constituent material properties change;

The length of the stirring time is given priority to with equipment performance, the amount of material;

Impeller used in pulp dispersion change difficulty, can't change can be to adjust the speed from slow to fast, in order to avoid damage to equipment;

Before discharge to sieve size, remove larger particles to prevent coating caused by broken belt;

For ingredients personnel should strengthen training, to ensure the master professional knowledge, in order to avoid the disaster;

Is the key ingredient in dispersed evenly, grasps the center, other ways can adjust itself.

A, battery production required parameters

1, sheet size

2, plasma technology

A) set fluid size

The anode (aluminum foil), intermittent coating

The cathode (copper foil), intermittent coating

B) slurry weight requirements

After 3, the anode paste for the following process:

Cutting large cutting small piece according to piece (with) baking flaking pole ear welding negative after the pulp for the following process:

Cutting large cutting small piece according to piece (with) baking flaking ear welding

4, flaking requirements

5, with solution

6, sheet roasted

Note: the vacuum degree of vacuum system for - 0.095-0.095 Mpa. Protection for high purity nitrogen gas, the gas pressure is greater than 0.5 Mpa

7, very ear

A) the positive:

The positive pole ear in the positive plate by ultrasonic welding. Aluminum bar end with flush plate edge.

B) negative:

Nickel size: 0.10 x 3.0 x 48 mm, nickel directly with spot welding spot welding, spot welding points to article 8 point nickel right aligned with the cathode piece on the right side, end of the article nickel and flush plate edge.

8 the diaphragm size: 0.025 * 44.0 * 790 + / - 5 mm

9 needle width: 22.65 + / - 0.05 mm

After 10 pressure core: battery winding, first in the bottom of the batteries, as 24 mm width of transparent tape, reoccupy cold pressing machine two times.

Requirements before 11 batteries into the shell

Gummed paper 1:10. 0 x 38.0 + / - 1.0 mm, gummed paper distributed evenly on both sides of batteries;

Tape 2:10. 0 x 38.0 + / - 1.0 mm, nickel strip in the middle of the tape.

Gummed paper 3:24. 0 x 30.0 + / - 2.0 mm, gummed paper distributed evenly on both sides of batteries;

Nickel strip on the right side is apart from the batteries on the right side of 7.0 + / - 1.0 mm.

12 pack shell

When packing and application of both hands, slowly the batteries into the battery shell, scratch batteries is prohibited.

13 negative pole ear welding

Anode nickel strip and steel shell with spot welding machine for welding, to ensure the welding strength, virtual welding is forbidden.

14 laser welding

Laser welding fixture should be carefully, can only be carried out after the battery shell and cover with good welding, pay attention to avoid the partial welding.

Vacuum bake 15 batteries

Remark:

(1) the vacuum degree of vacuum system for 0.095 ~ 0.10 MPa;

(2) protection for high purity nitrogen gas, gas pressure > 0.5 MPa;

(3) a vacuum injection every hour nitrogen

16 injection fluid volume: 2.9 + / - 0.1 g

Liquid injection room relative humidity: 30%, or less temperature: 20 + 5 ℃ for the sealing tape: 6 mm wide red tape, glue paper pay attention to wipe note when liquid electrolyte of mouth with 2 rubber band will cotton fixed to the injection liquid mouth.

17 into system

(1) opening into the process

A) constant current charging: 40 ma x 4 h.80 ma * 6 h

Voltage limits: 4.00 V

B) all inspection voltage, a voltage of 3.90 V or more batteries for sealing, voltage < 60 ma constant current is 3.90 V battery to 3.90 ~ 4.00 V after sealing, to play ball

C) battery cleaning, cleaning agent for acetic acid + alcohol

(2) into a system

According to the program to continue to:

A) constant current charging (400 ma, 4.20 V, 10 min)

B) to sleep (2 min)

C) constant current charging (400 ma, 4.20 V, 100 min)

D) constant voltage charging (150 min) 4.20 V, 20 ma,

E) dormant (30 min)

F) electric constant exile (750 ma, 2.75 V, 80 min)

G) to sleep (30 min)

H) constant current charging (750 ma, 3.80 V, 90 min)

J) constant voltage charging (150 min) 3.80 V, 20 ma,

(3) the detection points, let

Of the battery according to the following class of points:

Under the battery tank full inspection after voltage, voltage < 3.77 V battery USES the program to fill electricity:

(1) constant current charging (750 ma, 3.80 V, 10 min)

(2) the dormancy (2 min)

(3) constant current charging (750 ma, 3.80 V, 30 min)

(4) constant voltage (3.80 V, 20 ma, 60 min)

18 the battery the re-inspection

Battery capacity tank points placed at room temperature after 20 days to recheck, the steps are as follows:

A) plastic with plastic machine for batteries;

B) the whole thickness of the battery, voltage, resistance, classification method is as follows:

Second, the battery production process

1, (positive and negative) and dry mixing, wet mixing roller coating paste on the conductive substrate and dry step 3 - winding - trimming (cut into a certain width) - rolling - winding (standby) dry mix with ball mill, grinding ball is a glass ball or zirconia ceramic ball;

Wet mixed use. Planetary mix machine, its leaves in 2-3 axis respectively, mixing effect is better. Wet in the mixed solvent quantity appropriate, to form the right flow abnormal condition, in order to obtain a smooth coating. Roller coating electrode paste to guarantee a certain viscosity, paste on both sides of the aluminum foil and copper foil, and the thickness of the coating depends on the type of the battery. Then successively by three dry heating zone, NMP (or water) from the coating volatile with hot dry air or nitrogen gas flow, and the solvent can be recycled. Roller is in order to improve the density of the coating, and the electrode thickness to comply with the size of the battery assembly, pressure roller stage wants moderate, to avoid powder scattered when winding.

2, battery assembly

Cylindrical battery assembly process: insulation ring into the cylinder to winding batteries into the cylinder, insert core shaft to welding the cathode current collector piece in steel cylinder, insert the insulation ring - steel cylinder rolling line - vacuum drying to filler, cap (PTC element, etc.) on welded to the anode lead very - seal - X-ray - number - into - cycle - aging.

Square battery assembly process: insulation bottom into the steel box to flake combination batteries into the cylinder, the cathode current collector pieces welded steel box to the sealing gasket, the anode current collector piece of welding rod guide - combination cover (PTC element, etc.), welding and combination cover to spin a location to laser welding, vacuum drying to filler, seal - X-ray inspection - number - into - cycle - aging.

For cylindrical battery assembly process specification: for example the battery the same basic process (squares)., before aluminum strip winding core into the cylinder (0.08-0.15 ㎜ thick, 3 ㎜) and nickel (0.04-0.10 ㎜ thick, wide 3 ㎜) with ultrasonic welding in the designated place of positive and negative electrode conductive substrate as current collector extremely.

PE/PP2 commonly used battery diaphragm or PP/PE/PP3 layer of the diaphragm is after 120 ℃ heat treatment, in order to increase its prevent and improve its security.

The positive, diaphragm, negative 3 after composite winding into the cylinder, because use paste electrode, therefore, must make the paste and matrix with good material, to form a high-density electrode, especially to prevent off powder, lest its membrane caused by battery internal short circuit.

Before winding batteries inserted steel cylinder, put an insulating base into the bottom of the cylinder is to prevent internal short circuit the battery for general battery is the same.

Electrolytes generally USES LiPF6 and non-aqueous organic solvent, before the vacuum filler, the battery to vacuum drying / 24 h, to remove the battery components in water and moisture, in order to avoid LiPF6 react with water to form a HF and shortens life.

Battery sealing by the sealing glue, insert the gasket, edge and area reduction process, the basic principle is the same as the alkaline rechargeable batteries. After sealing, the battery with isopropyl alcohol and water mixture to remove dirt and oil spills of electrolyte, and then drying. Use a kind of smell sensor or "sniffer" element to check battery leakage.

The battery assembly is complete, with X-ray appraisal battery internal structure is normal, for batteries is not straight, steel shell crack, solder joints, check for short circuit, etc, to eliminate the defective battery, ensure the quality of the battery.

The procedure is into, first rechargeable batteries, protective film is formed on the anode, known as the solid electrolyte interphase (SEI) layer, it can prevent the anode reaction with electrolyte, and is the battery safe operation, high capacity, long life of the key elements.Batteries after a few charge and discharge cycle 2-3 weeks after Chen, remove the micro short circuit batteries, and then to capacity after sorting packaging becomes a commodity.

Third, the performance of the battery

1, electric performance:

(1) rated capacity: 0.5 C discharge, monomer battery discharge time not less than 2 h, battery discharge time not less than 1 h54min (95%).

(2) 1 c discharge capacity, 1 c discharge, monomer battery discharge time not less than 57 min (95%), battery discharge time not less than 54 min (90%);

(3) the low temperature discharge capacity: 20?C under 0.5 C discharge, monomer or battery discharge time were not less than 1 h12min (60%).

(4) high temperature and discharge capacity: 55?C under 0.5 C discharge, monomer battery discharge time not less than 1 h54min (95%), battery discharge time not less than 1 h48min (90%).

(5) charged to maintain and restore ability: full charge temperature for 28 days, keep charged discharge time not less than 1 h36min (80%), and charged back discharge time not less than 1 h48min (90%).

(6) storage performance: monomer battery or battery pack for storage and test elected since the date of the production of less than 3 months, before the storage charge 50% ~ 60% of capacity, the environment temperature of 40 ℃ plus or minus five? C, 45% ~ 75% relative humidity environment storage for 90 days. Storage after the expiration of take out the battery pack, with 0.2 charged aside after 1 h, C to 0.5 C to constant exile electric voltage, the above tests can repeat the test three times, discharge time not less than 1 h12min (60%).

(7) life cycle: the battery or battery charging by 0.2 C, 0.5 C discharge cycle, when the two consecutive discharge capacity is less than 72 min (60%) when to stop testing, monomer battery cycle life not less than 600 times, battery cycle life not less than 500 times;

(8) high temperature shelf life: elected since the date of the production of less than three months of monomer battery high shelf life test, prior to shelve should fill the capacity of 50% plus or minus 5%, then the environment temperature of 55 ℃ + 2?Under the article of C for 7 days. After 7 days to take out battery, in the environment temperature is 20 ℃ plus or minus five? Under the C for 2 ~ 5 h. Start with 0.5 C to termination voltage, the battery discharge according to 0.2 after 0.5 h C, let stand, after 0.5 h to 0.5 C electric constant exile to termination voltage, capacity as the recovery capacity. The above steps for 1 week cycle until a week discharge time is less than 72 min (60%), the experiment is over. Shelf life not less than 56 days (8 weeks cycle).

2, the safety performance

(1) continuous charging: at 0.2 ItA monomer battery to constant current charging, when monomer charging voltage of the battery to limit the voltage to constant voltage charging and keep the 28 d, after the test, should not leak, do not lose heart, no broken, no fire, no explosion (equivalent to a full charge floating).

(2) of charging, the monomer battery voltage source with the 3 c constant current charging with constant current and voltage after reaching 10 v to constant voltage charging, until the battery explosion or fire or charging time of 90 min or cell surface temperature stability (temperature difference within 45 min 2 or less?C) stop charging, the battery should be no fire, no explosion c10v (3);Use battery voltage source to It A 0.5 constant current charging, voltage reach n x 5 v (n for the serial number of monomer battery) to constant voltage charging, until the battery charging or fire or explosion time of 90 min or battery surface temperature stability (temperature difference within 45 min 2 or less? C) stop charging, the battery should be no fire, no explosion.

(3) mandatory discharge (reverse charge) : at 0.2 ItA monomer battery first to electric constant exile to termination voltage, and then to 1 ItA to reverse battery charging current, charging time no less than 90 min, the battery should be no fire, no explosion; Will be one of the monomer battery discharge the battery pack to termination voltage, the rest are charged state of battery, again with 1 ita electric constant exile to stop discharge when the battery voltage of 0 v, the battery should be no fire, no explosion.

(4) short circuit test: to pass through the external short circuit, 90 min, monomer battery or battery surface temperature stability (temperature difference within 45 min 2 or less?C) stop when the short circuit, the external circuit resistance should be less than 50 m Ω, battery should be no fire, no explosion; Will the battery pack is the cathode with less than 0.1 Ω resistance of copper wires connected until the battery voltage is less than 0.2 V or battery surface temperature stability (temperature difference within 45 min 2 or less?C), battery should be no fire, no explosion

3, mechanical properties,

Squeeze: (1) the monomer battery placed in the middle of the two extrusion plane, gradually increase the pressure to 13 kn, cylindrical battery extrusion direction perpendicular to the longitudinal axis of the cylindrical axis, square battery extrusion wide face and narrow face. Each cell can only accept a squeeze. Test results shall comply with the terms of 4.1.2.1.Put a 15 cm diameter on the battery pack steel rods wide face and narrow face extrusion battery of battery pack, extrusion to pack the size of the original 85%, maintain 5 min, each battery pack will only accept a squeeze.

(2) needle: single cells in a steel jig, from 3 mm ~ 8 mm steel nails from the perpendicular to the direction of the battery plate throughout the stay in battery (steel), 90 min, or cell surface temperature stability (45 min temperature 2 ℃ or less) stop the test.

(3) weight: placed single cells in a rigid plane, with a diameter of 15.8 mm of steel bar center flat on battery, steel bar of the vertical axis parallel to the plane, let weight 9.1 kg weight from 610 mm height free fall on the steel bar in the center of the battery; Monomer battery is cylindrical, the impact direction perpendicular to the longitudinal axis of the cylinder; Monomer battery is square, want to hit the battery wide face and narrow face, each cell can only accept a slam.

(4) mechanical shock; The battery or the battery pack with rigid fixation method, this method can support the battery or the battery pack all fixed surface) to the battery or battery pack is fixed on the test equipment. Each in three mutually perpendicular directions under the impact of an equivalent. To ensure that at least one wide surface vertical direction with the battery or the battery pack, each shock according to the following method: within the first 3 ms, minimum average acceleration is 735 m/s2, peak acceleration should be between 1225 m/s2 and 1715 m/s2.

(5) vibration: the battery or battery installed directly or through the fixture for vibration test on the surface of the vibration table. Test conditions for 10 hz ~ 55 hz frequency, acceleration of 29.4 m/s2, XYZ sweep in each direction cycles for 10 times, the frequency sweep rate for 1 oct/min.

(6) free fall: the monomer battery or battery pack by highly (low level) to the location of the 600 mm free fall to 20 mm thick hard wooden boards on the surface of the concrete, from XYZ one time in the three directions. After the free fall.

4, environmental adaptability

(1) high temperature baking: monomer battery to be included in the high temperature explosion-proof box to (5 + 2?C)/min heating rate up to 130 ℃, under the temperature of heat preservation for 10 min.

(2) high temperature storage: place the monomer battery or battery pack in 75 + 2?C in the oven on 48 h, battery should be, should not leak, do not lose heart, no broken, no fire, no explosion.

(3) the depression: UL standard).

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