How does a silicon-carbon battery for mobile phones work?

Earlier this week, Chinese smartphone maker Honor surprised audiences at the Mobile World Congress (MWC) 2023 auditorium in Barcelona by announcing the first silicon-carbon battery for use in mobile devices. The new component promises an energy density 12.8% higher than conventional lithium batteries.

The new technology has already passed the lab testing phase and may have become reality, at least in China, where the new Magic5 Pro is listed by Honor with a 5,450mAh battery. This represents around 6.8% more capacity than the 5,100mAh of the device’s global announcement.

Replacing the anode (positive electrode) of lithium batteries with similar ones made of silicon and carbon could be the “holy grail” that major industries, including electric cars, seek to increase the autonomy of their batteries. For example, German Porsche invests multimillion dollars in this technology.

Why is the silicon-carbon battery more powerful than current batteries?

Current lithium-ion batteries operate with two metal electrodes immersed in a conductive liquid (electrolyte) that uses lithium salts with the necessary ions to create a reversible chemical reaction between cathode and anode. These electrodes, negative and positive, are electrical conductors in contact with a non-metallic element of the circuit.

Big take from the new smartphone batteries announced by Honor It is the replacement of the graphite anode found only in lithium-ion batteries with a silicon and carbon anode. The main element of the new composition is silicon, because although graphite manages to store large amounts of lithium ions in a relatively small space, each silicon atom can bind to four lithium ions.

This chemical reaction reflects the performance of batteries with silicon and carbon anodes, up to ten times superior to the charges of batteries with graphite anodes. While this is not very noticeable when both batteries are charged, it becomes critical when the voltage drops to 3.5 volts. Under these conditions, silicon-carbon has 240% more capacity than the current standard battery, as Honor CEO George Zhao explained.