Which car battery is the safest? Blade structure battery or cylindrical battery!

Nowadays, more and more people have to buy electric cars. First, because of the policy restrictions on the purchase and driving of fuel cars, they have to buy electric cars. Second, the oil price continues to rise, and the crazy money printing led by the United States will inevitably accelerate the rise in global oil prices. The cost of using fuel cars is higher than that of electric cars, and the price of electric cars continues to fall, etc. Many factors have led more and more people to pay attention to and buy electric cars. What is the most important thing when buying an electric car? Safety or battery life?

Electric vehicle range anxiety stems from the inconvenience of charging, while most people ignore safety when buying a car

Some people say it is the battery life. Most electric cars today have a battery life of more than 400 kilometers, and some even have models that can reach 1,000 kilometers. However, this still does not solve users' anxiety about battery life. The fundamental reason is that electric cars are inconvenient to charge. As long as charging is convenient and the fast charging time is greatly shortened, people may not care too much about their battery life. After all, no matter how long the battery life is, it will be most discounted in the cold winter; when driving at a highway speed of 120 kilometers per hour, the battery life will also be greatly discounted.

Knowing that the root cause of users' anxiety about battery life is the inconvenience and slow charging, we should gradually increase the construction of charging stations, which is also the focus of infrastructure construction today. With the advancement of battery technology, fast charging can also shorten the charging time. Take mobile phones as an example. In the past, it took 1 hour to fully charge the battery. Now there are fast-charging mobile phones that can be fully charged in less than 20 minutes.

Putting aside the endurance and talking about safety, the most talked about thing about electric vehicles in recent years is spontaneous combustion. In recent years, there have been dozens of electric vehicle spontaneous combustion incidents. These electric vehicles are mainly lithium-ion batteries. Why are lithium-ion batteries flammable? The following data is from the statistics of "Zhihua Automobile"!

Because the negative electrode material of lithium-ion batteries is graphite, which is highly flammable, and the electrolyte of the battery is ester solvents and lithium salts, and ester solvents are not only flammable, but also highly volatile. When the battery is installed on the chassis of the car, it is not conducive to volatilization. When the car is bumped into the bottom, it is easy to cause more intense combustion or even explosion.

Blade batteries still have lithium ions but the structure has changed to a blade shape

When lithium-ion batteries are discharged at high current, lithium dendrites are easily formed at the negative electrode, which pierce the diaphragm and cause internal short circuits in the battery and explosion. Lithium-ion batteries are not safe, and many electric vehicles are still using lithium-ion batteries. In recent years, a large number of electric vehicles have spontaneously caught fire, all of which are equipped with lithium-ion batteries. Does the blade battery promoted by BYD really have a lower risk of spontaneous combustion?

In fact, BYD's blade battery is not made of blades, it also contains lithium ions, namely lithium iron phosphate battery. Although the energy density of lithium iron phosphate battery is only 80% of that of ternary lithium battery, its biggest advantage is the best safety and will not spontaneously combust. In addition, the battery structure is designed to make it easier to dissipate heat and resist impact, that is, to make it thinner, that is, into a blade shape.

In terms of battery pack arrangement and combination, the volume utilization rate of blade-shaped batteries has increased by more than 50%. The space utilization rate of traditional cylindrical batteries is only 50%, while BYD's blade batteries can increase the space utilization rate of battery packs to more than 60% by changing the arrangement and combination of battery packs, which means that more batteries can be installed to increase battery life. In addition, the cost of blade batteries is also lower than that of ternary lithium batteries.

Allowing more blade-shaped batteries to be installed in the limited space of the car chassis and making them more resistant to puncture and pressure

Blade batteries do not increase the "energy density" per unit volume of the battery, but install more single-cell "blades" in a limited space to improve space utilization, thereby increasing the energy density of the entire battery pack and ensuring battery life. From BYD's test, a blade battery did not puncture and burn, but what about puncturing multiple blade batteries bundled together? Or crushing? The picture below shows that a ternary lithium battery exploded after being punctured!

Recently, BYD has also conducted a crushing test on the blade battery. The blade battery on the chassis of the BYD Han was removed, and then a BYD heavy truck with a counterweight of 46 tons was used to crush the battery. However, because the blade batteries of all BYD's blade batteries, such as the Han, are packaged vertically with gaps, they have the structural advantages of physical combination in terms of resistance to crushing, bottoming support and acupuncture. In the end, the 46-ton heavy truck crushed the Han's blade battery three times without any battery leakage or deformation. Finally, it was put back on a YuAD Han electric car. If it was deformed, the battery could not be put back.

Is the BYD blade battery that does not burn when pierced by a needle, does not deform when crushed, and does not leak liquid really that magical? What if you squeeze it hard? Squeezing it in the vertical direction will only cause smoke, but no explosion. What if you squeeze it in the horizontal direction, after squeezing the entire blade battery into a pile, will the smoke be greater or even cause an explosion? It is unknown. However, such extreme situations are unlikely to occur. After all, car accidents are front-to-back collisions, and the probability of side collisions is very low.

Final Thoughts

BYD's announcement that it will "completely erase spontaneous combustion from the dictionary of new energy vehicles" still needs to be watched. After all, the spontaneous combustion of electric vehicles is not only related to the battery, but it is also possible that if the circuit is short-circuited and burns the line, spontaneous combustion may occur. However, the use of blade batteries will certainly reduce the risk of battery spontaneous combustion. It has to be admitted that blade batteries use lithium iron phosphate materials with higher thermal stability, and their comprehensive performance is better than the mainstream ternary lithium materials at this stage. Through the flattened long battery cell design, it can effectively increase the energy density. Coupled with the external protective cover, it forms a structure with strong rigidity, so it is not afraid of crushing, and the lithium iron phosphate material has high voltage power generation capabilities.