Calcium-ion batteries in smartphones? What's the verdict?

If I have to point to one technology that has been hampering our development over the past decades, that would be batteries. The lithium-ion battery dates back to the 1960s, and the main principle has stayed the same ever since.

However, we're on the verge of a big shift in battery tech, as the wide adoption of electric vehicles, along with new advances in material science, is finally promising to remove this bottleneck from our battery-powered gadgets.

I'm following closely the new and quite hyped solid-state battery from Donut, but there are other approaches that can offer an alternative to our old lithium-ion batteries. And just mere hours ago one such alternative reached a crucial milestone. Calcium-ion batteries.

What is a battery, and how does it operate?

Without getting too technical (there's a separate article for that), let's quickly go through what a battery is and how it operates. Put simply, a battery is a device that stores energy through electrochemistry. There are three main components involved — an anode, a cathode, and an electrolyte.

It's all about moving charged particles (electrons and ions) from the anode to the cathode and vice versa. When you charge a battery, you connect an external source to the anode and cathode and make charge particles flow from the cathode, through the electrolyte, and to the anode, bunching up there waiting to power your gadget.

When you connect an external load to the battery, let's say your smartphone, stored charged particles start flowing from the anode through your smartphone and back to the cathode of the battery. This electron flow effectively powers your device.

What's the problem with lithium anyway?

We've been using lithium as a main component in the cathode and electrolyte parts of batteries for decades. There are certain pros and cons to this element. Lithium-ion batteries offer good energy density, relatively fast charging, and decent longevity.

However, lithium reacts violently with air, making lithium-ion batteries unsafe when damaged. If you puncture a lithium ion battery, it can combust and even explode, and these fires are notoriously hard to put out.

Lithium-ion batteries also require a narrow temperature and voltage range to operate properly, and finally, we're close to reaching the theoretical limit of the energy density of the lithium-ion battery.

Today we're using tricks such as imbuing the anode with silicon to increase the energy storage capacity, but this approach can only delay reaching the inevitable ceiling of this technology. Lithium is also kind of rare, and mining it creates political rivalry and other geopolitical issues.

Enter the calcium-ion battery.

Calcium-ion batteries

I've covered briefly sodium-ion batteries in a separate article, but the star of today's article is calcium. The same material that makes up your bones and the one found in milk, among other places. Calcium is the fifth-most abundant mineral in the Earth's crust. It's abundant!

There are other benefits to using calcium in batteries. Calcium metal has high conductivity, and its high melting point (1547.6 F) makes calcium metal a safer choice for batteries. Calcium is also non-toxic and generally environmentally safer.

Furthermore, it has a higher theoretical energy density ceiling than lithium-ion batteries — 3202 Wh/L versus 2800 Wh/L for silicon-carbon lithium-ion batteries that currently sit at the top of the battery food chain.

Okay, so calcium is good, lithium — not so much. Why haven't we moved to calcium batteries already? What's the problem?

Calium-based electrolytes face electrode dissolution, basically degrading the capacity of the battery with every charge-discharge cycle. Here's where the new milestone comes into play.