A few days ago, BYD held a technical conference online. The protagonist of the conference was called "Blade Battery". According to Wang Chuanfu, it will completely solve the pain point of "spontaneous combustion" of lithium batteries and change the industry.
I happened to be reading some papers about batteries recently. Before I forget, I want to talk to you about the so-called "blade battery".
What is a "blade battery"?
According to the classification of cathode materials, lithium batteries can be roughly divided into lithium cobaltate, lithium manganate, lithium ferrous phosphate and lithium ternary.
But after years of trying, only lithium ferrous phosphate and lithium ternary are popular in the market or favored by the industry. The difference between them is that the former has low energy density and high safety, while the latter has high energy density and low safety.
The "blade battery", a seemingly second-rate name, is essentially a kind of lithium iron phosphate battery.
But it is different from the conventional lithium iron phosphate battery. BYD adopted a technology similar to that of Contemporary Ampere Technology Limited CTP, which cancelled the original battery module of traditional lithium batteries and directly integrated the batteries into a battery pack.
Among them, the cells that make up the battery pack are thin and similar to the shape of blades, so they are called "blade batteries".
What are the characteristics of "blade battery"?
The first is higher security.
There are three main reasons for this. On the one hand, during the charging process of lithium iron phosphate battery, lithium ions constantly escape from the positive electrode and move to the negative electrode. When the power is about to reach saturation, lithium ions can be completely embedded in the negative electrode, thus forming "overcharge protection";
On the other hand, the P-O bond of lithium iron phosphate battery is stable and difficult to decompose, and it will not cause the structure to collapse and heat or form strong oxidizing substances even at high temperature (above 390℃);
Moreover, the combustion of lithium iron phosphate battery needs the supply of external oxygen. Once spontaneous combustion occurs, the fire can be controlled by cutting off external oxygen. Moreover, because of the battery material, the burning speed of "blade battery" is slow and the burning degree is not intense.
But the above are only the most basic characteristics of lithium iron phosphate battery, and BYD's "blade battery" is based on this, adding two protective measures-
One is the vertical discharge of "blade battery" to change the bending section of the battery and improve the strength of the battery pack;
Second, two high-strength plates are attached to the upper and lower sides of the battery to form a honeycomb aluminum plate structure to strengthen the strength of the battery pack.
Therefore, compared with the ternary lithium battery, the "blade battery" will not explode or burn due to excessive temperature, overcharge, short circuit, impact and other reasons. Even if it spontaneously ignites, a pure electric vehicle equipped with a "blade battery" will have more time for the owner to escape.
BYD also said at the press conference that "Blade Battery" passed the four tests of acupuncture, oven temperature, extrusion and overcharge, and also released a full version of acupuncture video.
I have to admit that BYD is quite bold and has real materials. After all, few car companies dare to release this test, and they must be very confident in their products.
But I'm still skeptical about it. After all, the test of a single "blade battery" cannot represent the whole battery pack, which depends on the subsequent market inspection. Of course, this is another story.
Secondly, the space utilization rate is good.
As mentioned above, BYD's "blade battery" adopts a technology similar to CTP of Contemporary Ampere Technology Co., Ltd.
Generally speaking, the traditional battery assembly is "cell-module-battery pack" mode, that is, the cells are assembled into modules first, and then the modules are put into the battery pack.
And the so-called CTP, its full name is Cell? Where to? Pack, as its name implies, cancels the intermediate module assembly link and directly integrates the battery cells into the battery pack.
The battery pack without the module reduces many parts for assembling the module, thus reducing the manufacturing process of the battery pack, saving the labor cost of materials and improving the volume utilization rate of the battery pack in one fell swoop.
At the same time, it also means that BYD's "blade battery" can further improve the energy density of the battery by increasing the capacity of the single battery and optimizing the battery structure.
This makes up for the problem of low energy density caused by low tap density and compaction density of lithium iron phosphate battery to some extent.
However, "blade battery" is not perfect. For example, the lithium iron phosphate battery has poor low-temperature performance due to factors such as particle size and electrolyte raw materials, especially in the north where winter is basically below zero degrees Celsius, which limits the application scope of "blade battery" to some extent.
BYD didn't explain the low-temperature performance of the battery at the press conference, which deepened my doubts about the low-temperature performance of the "blade battery". But it is reasonable to say that battery research and development will definitely do low temperature testing, so I hope BYD can give a statement in the future.
For example, battery cell consistency and thermal management are challenges that "blade batteries" have to face.
Lithium Ternary and Lithium Ferrophosphate
In fact, when Wang Chuanfu talked about solving spontaneous combustion and changing industries, I couldn't help thinking of Tesla. After all, Tesla uses a ternary lithium battery that is easy to spontaneously ignite, and it was deeply troubled by spontaneous combustion earlier.
Frankly speaking, the struggle between ternary lithium battery and lithium phosphate battery has always existed.
In the early years, due to the increasing requirement of policy subsidies for cruising range, everyone rushed to get ternary lithium batteries, including BYD itself, which gave up the previously developed lithium iron phosphate battery and switched to ternary lithium batteries.
However, in the past two years, with the continuous decline in subsidies for new energy vehicles, the blessing of new technologies for power batteries and the emergence of CTP technology, lithium iron phosphate batteries have begun to emerge again.
According to the first batch of passenger cars recommended by the Ministry of Industry and Information Technology in 2020, the proportion of passenger cars equipped with lithium ferrous phosphate has reached18% (7.8% in 2019).
Therefore, according to the current trend, the future battery pattern will probably be divided into two parts: lithium ternary and lithium ferrous phosphate. As for which is stronger and which is weaker, it still depends on the efforts of subsequent car companies.
But what is certain is that BYD, which has mass-produced "blade battery", has created its own new era on the road of battery, and has also seen the dawn of the dream of overtaking in corners.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.