The mobile gadget market is developing rapidly every year. Cameras are improving, more powerful processors are being offered, artificial intelligence functions are being introduced, and so on. However, reliable batteries with fast charging cycles and high capacity remain one of the main requirements from users.
And while most smartphones still use lithium-ion and lithium-polymer batteries with a maximum capacity of about 5000 mAh, this usually has to be achieved by increasing the battery’s size, sacrificing either some individual functional modules or increasing the size and weight of the mobile device itself.
However, this year, significant changes are expected in this regard, as Li-Ion and Li-Pol batteries will gradually be replaced by silicon-carbon batteries (Si-C). What is their advantage, and what hinders their massive and rapid implementation? Let’s have a closer look.
Design differences
To begin with, lithium-ion batteries themselves consist of an aluminum cathode and a copper anode. The cathode is usually coated with cobalt and lithium oxide, and the anode is covered with a thin layer of graphite. Between the cathode and anode is an electrolyte that allows lithium ions to move freely between them during the charging and discharging process.
The fundamental difference between Li-Ion and Li-Pol batteries is the electrolyte. While in lithium-ion batteries it is a porous separator impregnated with electrolyte, in lithium-polymer batteries it is a special polymer-based electrolyte.
Structurally, the only difference between Si-C batteries and traditional Li-Ion and Li-Pol batteries is the anode covered with a layer of nanostructured silicon-carbon composite material.
For many decades, graphite-coated anodes have been something of a standard, but not because they were so perfect, it was just that for a long time, it was not possible to find a worthy alternative that would work consistently and be as versatile.
However, silicon can hold 10 times more lithium ions than graphite. The energy density of such a battery can reach up to 4200 mAh/g versus 372 mAh/g for a graphite battery. This makes it possible to significantly increase the battery capacity without increasing its size, or to develop a compact battery without reducing its capacity.
The technology of silicon-carbon batteries was first proposed by developers from Stanford University back in 2008. However, there was one significant problem. The silicon coating on the anode, when absorbing lithium ions during charging, increased in volume by up to 400% and then shrank during discharging, which led to rapid destruction of the structure and prevented the creation of a reliable battery.
This problem was solved by adding fracture-resistant carbon nanostructures to silicon.
Pioneers of new technology
However, it was only in 2020 that developers from the Chinese company Honor managed to come close to commercializing such batteries.
Following Honor, Xiaomi, another Chinese company, began to install Si-C batteries in its smartphone models. Thus, the new Redmi Turbo 4 received a 6550 mAh battery.
What to expect next
According to insiders, Apple and Samsung are also considering switching to Si-C batteries. In particular, there are rumors that Samsung is already actively working on the development of batteries of this type, although the timing of their appearance in new models of the brand remains unknown.
Carbon nanostructures also help to maintain stable battery performance, preventing degradation even at extreme temperatures from —20 C° to 45 C°, which theoretically extends the battery’s service life to at least 4-5 years. Not only do these batteries tolerate low temperatures better, but they also provide increased safety due to less heat during active use, and especially during charging.
Another important advantage of silicon-carbon batteries is that they support ultra-fast charging with a capacity of up to 60 W per cell.
Currently, the main disadvantage of Si-C batteries is likely to be the price of smartphones equipped with them, as they will appear mainly in flagship gadgets in the coming years. Honor and other companies that have patented silicon-carbon batteries for smartphones have set high license fees for the use of this technology. So, we will probably have to be patient until these batteries appear in more budget gadgets.