The blade battery is just a small step in Wang Chuanfu's layout. Turning BYD into an open platform in the field of new energy vehicles is Wang Chuanfu's ambition.
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"Blade Battery", are you looking forward to it?
Yesterday (March 29), BYD officially released the “Blade Battery” ahead of Tesla Battery Day.
As a battery that claims to have more than 300 invention patents, the biggest highlight of the blade battery is: safety, safety, safety.
Wang Chuanfu, Chairman and President of BYD Group, said confidently: "The Blade Battery embodies BYD's determination to completely end the safety pain points of new energy vehicles, and is more capable of leading the global power battery technology route back to the right path and putting the The word 'spontaneous combustion' has been completely erased from the dictionary of new energy vehicles."
BYD's "Blade Battery" uses a new structure of "super lithium iron phosphate battery" by removing the battery module. Carry out innovative packaging technology to increase battery energy density under the premise of safety.
It appears that BYD’s blade batteries flatten and elongate single cells into a “blade” shape, and then assemble multiple elongated single cells to form a battery pack.
It is reported that the length of the blade battery ranges from 435mm, 905mm, 1280mm, 2000mm to 2500mm, and the thickness is reduced to 13.5mm.
He Long, vice president of BYD Group and chairman of Fudi Battery, said, “This structural design solution can not only effectively improve the space utilization of the power battery pack, but also increase the energy density in the same unit volume; It can also ensure the thermal diffusion performance inside the battery to achieve safety."
At the scene, He Long used a ruler to demonstrate why the blade battery has the advantages. First, he placed a ruler on it. If the ruler is flat, it will be easy to break, but if you rotate the ruler 90 degrees, it will be difficult to break.
This ensures the basic strength of the blade battery.
In order to further verify the safety of the "blade battery", BYD demonstrated a one-shot battery acupuncture test at the online press conference.
At present, the acupuncture test is the most stringent safety test for vehicle power batteries. However, since most batteries currently fail to pass this test, the 2015 version of the national standard mandates acupuncture. Optional test items are optionally implemented by enterprises.
The battery acupuncture test uses a steel needle to pierce the battery plate, which instantly triggers an internal short circuit in the battery, causing thermal runaway of the battery.
According to the acupuncture test method of GB/T? 31485-2015, the battery needs to be fully charged first, and a high-temperature resistant steel needle with a diameter of 5-8mm is used at (25±5) mm/s. The speed is to penetrate from the direction perpendicular to the battery plate. The penetration position should be close to the geometric center of the stabbed surface. The steel needle stays in the battery and is observed for 1 hour. It is considered qualified if there is no fire or explosion.
In addition to BYD's latest blade batteries, this acupuncture test also selected ternary lithium-ion batteries and ordinary lithium iron phosphate batteries for comparison.
In order to more intuitively observe the temperature changes of the three batteries, BYD has added a fried egg link for the battery. If the battery thermally runs out of control, its shell temperature will rise rapidly, and the heat diffusion between batteries will The faster it is, this means that nearby batteries will heat up faster and trigger thermal runaway one after another, resulting in a decrease in the safety factor of the battery pack.
If the eggs in the experiment are fried quickly, it means that the battery has obvious thermal runaway when it is punctured by acupuncture, causing the battery temperature to rise sharply.
Under the same test conditions, the first test was a ternary lithium battery. The moment the steel needle pierced the battery, the ternary lithium battery case expanded rapidly, and then the pressure relief valve opened. Extreme thermal runaway occurred - a violent combustion phenomenon, the eggs on the surface of the battery were blown away, and the surface temperature quickly exceeded 500°C.
The next is the ordinary lithium iron phosphate battery. The steel needle penetrates the internal plate from the center of the battery. After the steel needle penetrates the battery, the battery voltage begins to drop, and the battery shell bulges to a certain extent, indicating that The internal short circuit caused the internal pressure of the battery to rise rapidly. Then the pressure relief valve opened and the high-voltage electrolyte inside the battery spurted out. The results showed that after being punctured, the block lithium iron phosphate battery had no open flames but smoke, and the surface temperature reached 200°C~400°C. ℃, the eggs on the surface of the battery are burned by the high temperature.
The reason why the thermal runaway reaction of lithium iron phosphate batteries is not as severe as that of ternary lithium-ion batteries is mainly because the decomposition temperature of the cathode material is above 500 degrees Celsius, and the thermal runaway temperature is higher than that of ternary lithium-ion batteries. The risk of thermal runaway is relatively low.
The last test was BYD's blade battery. After the steel needle penetrated the plate of the blade battery from the center, the battery voltage dropped and the surface temperature increased slightly. There were no sparks, smoke or electrolyte ejection at the puncture location. There is no bulging in the battery case either. Within one hour after puncture, there was no open flame or smoke in the battery. The temperature on the surface of the battery was only about 30-60°C. The eggs on the surface of the battery did not change and were still in a flowable liquid state.
As for the performance of BYD's blade batteries in acupuncture experiments, Ouyang Minggao, an academician of the Chinese Academy of Sciences, analyzed and pointed out that the design of the blade battery makes it produce less heat and dissipate heat quickly during short circuit, and evaluated the performance of the blade battery as "very Excellent".
According to BYD officials, the "blade battery" can skip "modules" when forming a group through structural innovation, which greatly improves the volume utilization and ultimately allows more batteries to be packed into the same space. Core design goals. ”
How to increase energy density while being safe?
BYD applied for three patents for its “blade battery” last year: CN20191054429, CN201911011713 and CN201911012284. Through a simple The query can clearly see BYD's "blade battery" structural design idea.
In order to further increase the battery capacity in the limited body space, BYD has adopted CPT (cell?to?pack) technology. /p>
The principle is to directly package the battery cells in an array with a length of lithium iron phosphate cells in a battery pack of "600mm?≤?First size?≤?2500mm?" The battery cells are arranged together in an array, thus eliminating the step of assembling the battery cells into modules. This design can eliminate the need for additional parts such as beams, longitudinal beams, and various bolts while ensuring safety, thus making The number of battery pack components is reduced by 40%, the battery pack volume utilization is increased by 15%-20%, and the production efficiency is increased by 50%.
It is reported that compared with traditional molded battery packs, "blade batteries" "The weight specific energy density can reach 180Wh/kg, which is about 9% higher than the previous model battery pack. The energy density of the battery is about 50% higher than that of traditional iron batteries in the same volume.
He Long said, “The blade battery can increase the cruising range by more than 50%, reaching the same level as high energy density ternary lithium batteries. "
According to Wang Chuanfu's on-site disclosure, "The blade battery is only used in BYD Han pure electric models, and there are no plans for other models. Its cruising range under comprehensive operating conditions reaches 605 kilometers. ”
BYD’s blade batteries will be produced in Chongqing Fudi Battery Co., Ltd. As an independent sub-brand of BYD, Fudi series includes Fudi Battery, Fudi Power, Fudi Technology, Fudi Technology, Five subsidiaries, including Di Vision and Fudi Mold, form a complete auto parts supporting system.
He Long revealed that almost all imaginable car brands are discussing 'blade batteries' with BYD. Technical cooperation plan."
It can be seen that the blade battery is only a small step in Wang Chuanfu's layout. Turning BYD into an open platform in the field of new energy vehicles is Wang Chuanfu's ambition.
This article comes from the author of Autohome Chejiahao and does not represent the views and positions of Autohome.