How does BYD guarantee the safety of dynamic lithium-ion battery?

　　Author ：Iflowpower – Portable Power Station Supplier

In recent month, new energy car safety accidents frequently. According to incomplete statistics, only the number of electric cars that occurred in the two months of this year, the total number of fire accidents in 2017 throughout 2017. It is worth noting that many of these electric cars are in the fire accident, there are many powered lithium-ion batteries.

It can be seen that the reliability of the power lithium-ion battery is related to the personal and property safety of the consumer. So, why do the power lithium-ion battery taken by electric car? What measures do the battery packages do? The thermal out-of control is the true, power of the dynamic lithium-ion battery. The lithium-ion battery is large, and the original is caused by thermal out of control.

At present, the construction of pure electric vehicles is still not very perfect. Consumers are convenient to pure electric cars. It is not easy to reach the fuel cart.

Is a consumer or a new energy product, there is a certain requirement for the battery life. Therefore, there is a three-yuan lithium-ion battery that has a light weight and high power, is used by many new energy car companies. However, the three-dimensional lithium-ion battery has a fatal disadvantage, which is easy to cause a fire accident after the vehicle has collided, and the principal, the thermostat caused by the overheating of the battery.

(The pre-used lithium iron phosphate ion battery is not easy to start after the collision, the weight is slightly heavy, the power is slightly smaller, so it has gradually replaced by a three-dimensional ion battery) in the pure electric vehicle, The power lithium-ion battery system is composed of a plurality of power lithium-ion battery cells, and a large amount of heat is concentrated in a small battery case during operation. If calories cannot be quickly scattered in time, it will not only affect the life of the dynamic lithium-ion battery, but also the phenomenon of thermal out-of control, thereby causing accidents such as fire explosions. If in principle, there are four cases of the principle of thermal out-of control, that is, mechanical abuse, electrical abuse, heat abuse, and internal short circuits.

Mechanical abuse is to mean that when the car crashes, due to external force, the lithium-ion battery cell, the battery pack is deformed, and the relative displacement of the different parts, causing the battery diaphragm to tear and occurs internal short circuits, and the fuel electrolyte leakage Ultimately trigger a fire. In mechanical abuse, puncture damage is most serious, it may cause the conductor to insert the battery body, resulting in a positive and negative pole straight short circuit. And the electrical abuse is caused by improper use of the battery, and has several types of external short circuit, overcharge and excessive discharge.

Among them, because the transition discharge is minimal, the rise of copper delegths caused by excessive discharge will reduce the safety of the battery, thereby new increasing power chances. The external short circuit is the result in two of the two pressure differential conductors in the electrical core. When the external short circuit occurs, the heat of the battery cannot be spread well, and the battery temperature will rise, and the high temperature trigger heat is out of control.

Finally, excessive charging is a kind of harmfulness of electric abuse. Due to excess lithium embedding, lithium branch crystal is growing on the surface of the anode. And the excessive deinterling of lithium causes the cathode structure to crash due to heat and oxygen release.

The release of oxygen accelerates the analysis of electrolyte, a large amount of gas. Due to the new internal pressure, the exhaust valve is opened, the battery starts exhaust. After the active substance in the battery is in contact with air, a dramatic reaction occurs, puts a lot of heat, thus causing the battery pack to burn fire.

Next is hot abuse, this is to refer to local overheating in the battery, which is very few independent, often through mechanical abuse and electrical abuse, and is a case in the final straight triggering. Hot abuse is generally too high for external ambient temperatures, or short-circuit caused by high heat generation caused by temperature control systems, thus causing heat out of control. From the protocol, the collision, damage, the structure, performance of the battery, the structure, performance or other thermal management system, the failure of the air conditioning system can lead to heat abuse.

Finally, it is internal shortage. This situation is caused by the positive and negative pen of the battery, usually caused by mechanical abuse and thermal abuse. The internal short circuit is caused by the same complex, such as the excessive charging of lithium ion batteries.

The accumulation of dendrites can cause piercing the battery diaphragm, thereby interior short circuit or collision, after puncture damage, leading to the positive and negative contact. It can be seen that in the fire accident of pure electric vehicles, it is usually caused by the above four situations, and external accidents are aimedian factor. It is also because of this, for the battery pack manufacturer, it will cause a fire accident for alert or above, which will not only be very cautious in battery processing, but also conduct a series of test experiments.

Among them, BYD is worthy of praise in this regard. BYD batterically guaranteed the safety of the battery in R & D, in order to guard against the battery, BYD battery has been avoided to avoid risks to a certain extent during research and development. The battery used in BYD passenger cars is basically a ternary lithium ion battery, also known as a three-dimensional lithium ion battery, which refers to a positive electrode material using nickel-cobalt-oxanate or lithium nickel-cobalt-oxide.

Lithium ion battery for ternary positive material. The positive electrode material used by BYD's ternary lithium-ion battery is lithium nickel-cobalt-oxygen-melate, which is the same as the lithium-cobalt-aluminate ion battery, while the energy density is higher, ensures balanced battery, stability, so it will become Preferred in the current consumer-grade electric vehicle power lithium ion battery. However, the thermal stability of lithium nickel-cobalt-manganese acid is better than that of nickel-cobalt-aluminate, and the ratio of nickel content is small, and it is better to make the balance of life and safety while increasing energy density.

Therefore, it is more secure as a power lithium ion battery. Second, the lithium-ion battery is divided into two major categories of hard shell and soft bag according to the electrical cell, and the hard shell material is desirable for steel shell and aluminum shell, and the soft bag is an aluminum-plastic composite film material. Among them, the hard shell is divided into cylindrical and square shell type according to the arrangement of positive and negative poles in its internal.

Simply, the most mainstream battery packages are three types, cylindrical, square shell type and soft bag type. BYD uses square aluminum shell packages, which can make the internal material of the battery more tightly, plus aluminum shell constraints, not easy to expand, so relatively safe. In addition, the square shell package can be equipped with an explosion, and if there is a heat loss, the expansion air is released from the fixed direction of the prestige, it is not easy to affect other battery cells.

And because the square package is used, the cell gap is extremely small, and the aluminum housing has a small density, the weight of light is light, and the battery energy density of the square shell package can be higher. It is also worth mentioning that BYD's battery management system monitors the battery state by real-time, when the battery pack temperature is abnormal, heat dissipation or heating through the air conditioning system, ensuring battery safety and life. And on the power-based lithium-ion battery intelligent temperature control system, the power lithium ion battery pack adds a battery heating, cooling function, and simultaneously optimizes the new heat-insulated thermal insulation function, so that the battery works in a suitable temperature range, extend battery life.

Strict test experiments are better to ensure that battery safety can be seen by the above, and BYD batteries have greatly guaranteed the safety of batteries in R & D production. Of course, in order to better test the safety of the battery, BYD also made a series of harsh test experiments during the R & D of the battery, and the experimental project was desirable to simulate the situation where consumers may meet in the daily use of consumers. Charge, short circuit, squeezing, acupuncture, fire, etc.

The overshoot test is important to simulate the daily charging process of lithium ion batteries to verify the reliability and safety of the battery. It is necessary to charge the current specified by the battery, until the battery pack or monomer battery reaches the specified voltage until the battery module is fully charged. Then stand, observe the battery in accordance with time.

The experiment simulation is a battery short circuit failure. In short-circuit experiments, the internal power lithium ion battery will pass through a very short-circuit current, the battery is generally generated, bulging, safety valve pop-up, etc., extreme cases will fire, appear Strong smoke, even explosion, etc.

It is necessary to carry out the specified environment (normal temperature or high temperature), place the battery used in the matching explosion-proof box, and the external short-circuit simulation detection of the sampled sample is performed with the sampled sample to complete the simulation. Battery external short circuit detection. The purpose of this trial is to improve or improve the technology, new battery reliability and safety.

Image017.jpg Extrusion Test For the simulation of accidents, when the vehicle body is severely deformed, the battery is being squeezed when the battery is extruded, and the battery is damaged by extrusion deformation, or causes hidden dangers such as fire, explosion. It is necessary to place the monomer battery or battery module used in the experiment in the operating device, and the semi-cylindrical extrusion plate specified by the radius is perpendicular to the squeezing speed of (51) mm / s in the direction of the battery polar plate.

The degree reaches the voltage of 0V?. And observe 1 hour, the test requires that the battery does not afford fire, not exploding. The experiment also simulated the accident when using the car, the battery was pierced by a sharp object, and through technical means to prevent foreign body, the internal short circuit, which caused hidden dangers such as fire, explosion.

The experiment was carried out at ambient temperature of 20 ¡ã C ?? 5 ¡ã C, and the cells used in the detection were placed on the test equipment, and the largest surface of the battery was pierced with a predetermined size of the non-vase steel needle. The center position, the test requires that the battery does not afford fire, not exploding. After the fire test simulates the battery pack or the system is installed on the electric vehicle, the electric vehicle has suddenly elevated when the electric vehicle is high temperature ground or a flame.

During the test, observe the battery pack or system in a short period of time, due to the various conditions that the temperature is suddenly increased. In the experiment, the lithium ion power battery module used in the test equipment is placed in a predetermined test equipment or a field, and the spending temperature will continue to combust, the test requires no explosion, fire, combustion, and no fire seedlings remain. In addition, BYD has carried out low temperature durable, high temperature durable, salt water soaking, falling, and vibration detection.

Through comparison of the Adudi battery and the testing process, it is known that the BYD power lithium ion battery is trustworthy in reliability and product quality. BYD pure electric car battery is safe, life is long enough, about consumers, after ensuring battery safety, but more attention to the endurance mileage of pure electric cars, how is the endless miles of the pure electric car? Here we have chosen BYD pure electric cars that consumers familiar with, let's take a look at how these cars have the endless miles. The Yuan EV360, which is a 100,000-level pure SUV leader, sold 5008 units in September this year.

It is enough to see this car is loved by consumers. This car is equipped with the latest three-dimensional ion battery in BYD. The battery pack capacity is 43.

2kW / h, and the energy density is 146.27Wh / kg. Its integrated battery life is 305km, and in 60km / h isometrics, Mileage can also reach 360km.

BYD E5 as a consumer's most familiar electric vehicle, sales of 4052 in September, and this car also equipped with a three-dimensional lithium-ion battery. The battery pack capacity is 60.48kw / h, and its comprehensive battery life 400M.

The BYD Qin Proev serves as a new car recently listed, the battery capacity is 56.4kWh, and its integrated battery life has reached 420m. It can be seen from these best-selling models that BYD mount the power lithium-ion battery in terms of battery life to meet consumers.

Editor's comment: Many battery companies and car companies are pursuing higher energy density to get more subsidies, but ignore the most fundamental security attributes of dynamic lithium-ion batteries, and recent frequent accidents will also power lithium ions. Battery security takes once in the field of view. As the earliest company in China, the earliest company in China, BYD has always maintained a high level of safety during the development of the dynamic lithium-ion battery.

And we can also see all the harsh probes in BYD in the battery processing process, which always puts the safety of consumers in the first place. Therefore, BYD processing is trustworthy.