In recent years, more and more smartphones have been released using silicon-carbon batteries. This technology gained popularity after being adopted by Chinese manufacturers such as Honor, Oppo, and Xiaomi. Samsung has now joined this group, utilizing silicon-carbon in the batteries of its Galaxy Z Fold 8 and Z Fold 8 Ultra models.
According to Engadget, such batteries can possess significantly greater capacity compared to traditional lithium-ion ones. Some devices equipped with this technology are capable of operating for up to two days on a single charge.
How does the battery work?
The battery consists of three main components: an anode, a cathode, and an electrolyte located between them. When the battery is fully charged, all electrons remain in the anode, which slowly releases them toward the cathode. The flow of electrons through the electrolyte causes a series of electrical and chemical reactions that release energy. In standard smartphones, multiple additions of electrons can be made to the anode. However, over time, the stored energy decreases because the electrolyte loses materials necessary for the reaction.
Lithium-ion batteries
Lithium-ion batteries are popular due to their lightness, high energy density, and ability to withstand many charge and discharge cycles before degradation begins. Typically, a lithium-ion battery includes graphite powder as the anode, lithium phosphate powder as the cathode, and ethylene carbonate as the electrolyte.
What are silicon-carbon batteries?
Calling these cells silicon-carbon batteries is somewhat inaccurate: they still use lithium material in the cathode. Furthermore, current physics does not allow for the creation of an anode entirely from silicon-carbon. In fact, only a small percentage of silicon-carbon is mixed with existing graphite in these cells.
Samsung positions itself as the largest smartphone manufacturer to implement silicon-carbon cells. The company stated that it does not aim to produce cells with very high capacity, as seen in some Chinese devices. The new Z Fold line of phones uses a small amount of silicon to reduce battery size and, consequently, the entire hardware. In regulatory documents submitted to the European Union, Samsung reported that the lifespan of these cells will be only 1200 charge cycles, which is a noticeable reduction compared to the 2000 cycles claimed for the previous generation.
Advantages of silicon-carbon batteries
The advantages include:
- Superior storage capacity: Silicon has the ability to store up to ten times more energy per gram compared to traditional graphite.
- Higher energy density (smaller volume): This allows for the creation of batteries with significantly greater capacity while maintaining a thin and compact device form factor without increasing thickness.
- Faster charging: The silicon reaction ensures a faster process of lithium ion integration compared to slow penetration into graphite layers, thereby accelerating recharge speed.
- Availability and low cost: Silicon is cheap, widely available, and easily sourced raw material.
- Reduction of geopolitical risks: Using an abundant and widespread resource reduces dependence on supply chains and materials subject to international tension and conflict.
Disadvantages of silicon-carbon batteries
The disadvantages include:
- Shorter cell life: Batteries demonstrate slightly less durability and lifecycle compared to traditional technologies.
- Large volumetric expansion (physical deformation): Silicon expands by approximately 400% during the charge cycle (compared to only 10% for graphite), creating mechanical stress in the component and preventing the use of pure silicon.
- Need to balance capacity and longevity: There is a technical challenge in determining the proportion between silicon and graphite to achieve higher energy density without excessive compromise to service life.
