Understanding Xiaomi’s Silicon-oxygen Anode Battery

Xiaomi's Silicon-oxygen Anode Battery

Silicon-oxygen Anode Battery

In the Xiaomi 11 Pro/Xiaomi 11 Ultra warm-up period, Xiaomi’s official publicity materials released “the two phones will use a new silicon-oxygen anode battery”.

A time to see the majority of netizens confused: now eat melon too difficult, right? Knowledge reserves can not keep up with the speed of Xiaomi light up the technology tree.

In this issue, we will come to a comprehensive analysis of the Xiaomi flagship model using the “silicon-oxygen anode battery” in the end is what kind of technology.

This technology has been used in electric vehicle power, such as the solid-state battery technology innovation released by Weilai (蔚来) some time ago, which includes the use of silicon-carbon anode technology.

There are three main ways to improve battery capacity, respectively, is to replace the cathode material that can improve energy storage density, the use of new battery diaphragm technology, and replace the cathode material that can improve energy storage density.

At present, the innovation of positive electrode material for rechargeable batteries is mainly graphene positive electrode material, the role of this material is to enhance the battery charging speed, which can not effectively improve the energy density.

The transformation of the battery diaphragm technology is mainly to make the battery diaphragm thinner and thinner, however, too thin a battery diaphragm can easily cause danger. Therefore, replacing the new cathode material is the most cost-effective way to improve battery capacity.

This is mainly because the traditional battery cathode material is carbon material, carbon material as a battery cathode is characterized by a small expansion coefficient (about 10%), low energy density (theoretical gram capacity of 372mAh/g), although it is the ideal battery cathode material, but the same volume of the battery energy density is low.

The theoretical gram capacity of silicon material is about 4200mAh/g, but the expansion coefficient is high (about 300%); while the theoretical gram capacity of silicon oxide reaches 2615mAh/g, and the expansion coefficient is about 160%.

In human terms, silicon-oxygen cathode material achieves a balance between battery energy density and expansion coefficient.

The use of silicon-oxygen anode battery, smartphone enhancements are obvious, which means that the same volume of the battery will have a larger battery capacity, or control the battery capacity will be the thin and light design of the phone.

Xiaomi 11 Pro / Xiaomi 11 Ultra choose the former, the battery to 5000mAh, to protect the life.

Xiaomi 11 Pro/Ultra Review – Suggested Reading.

Silicon oxygen negative electrode battery mass production is difficult

The previous part of our comparison of carbon, silicon, and silicon oxide as theoretical gram capacity and expansion coefficient of the battery anode material, can be found is that the carbon material expansion coefficient is the smallest, 10%.

While the silicon cathode material battery although high energy density, this type of battery is easy to charge bulge. The above three battery anode material safety ranking is, carbon material > silicon material > silicon oxide material.

And this requires a breakthrough in wrapping materials, processing technology, adhesives, etc., which will affect the final cost of the whole battery. Besides, to make the battery charging more secure, Xiaomi in the configuration of fast charging did not choose 120W fast charging, choose 67W fast charging to ensure charging safety.


Finally, we summarize the advantages and disadvantages of the silicon-oxygen anode battery. Advantages: large capacity per unit gram, which allows the phone to have a larger battery capacity in the same battery volume; disadvantages: negative material expansion coefficient, charging safety needs to be controlled.

The silicon-oxygen anode battery such as electric car technology applied to smartphones can see that Xiaomi still put thought into it, silicon-oxygen anode battery really improve the experience of using smartphone batteries.

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