Tech Talk
How it works, explained in a way that everyone can understand. Your weekly look into what makes your gadgets tick.
Welcome to Tech Talk, a weekly column about the things we use and how they work. We try to keep it simple here so everyone can understand how and why the gadget in your hand does what it does.
Things may become a little technical at times, as that’s the nature of technology — it can be complex and intricate. Together we can break it all down and make it accessible, though!
You might not care how any of this stuff happens, and that’s OK, too. Your tech gadgets are personal and should be fun. You never know though, you might just learn something …
What is a solid-state battery and what makes them better?
The answer here is simple, but it leaves a lot of questions, especially if you’re interested in how things work even a little bit.
A solid-state battery is a rechargeable battery that uses a solid material electrolyte instead of the flammable liquid found in most Li-ion batteries today. That’s it, the whole enchilada. Energy still transfers the same way, and it functions just like the batteries you’re used to, only it’s a whole lot better. Why?
Changing the material the electrolyte is made of and changing its role make a handful of big differences. Mostly good ones. A “regular” battery is built like this:
You have two electrodes — a cathode (the positive pole) made of what’s called a cathodic material like lithium-iron phosphate, and an anode (the negative pole) made of an anodic material like graphite or carbon.
Between the two sits a central separator and insulator made of polyethylene that prevents them from ever coming into direct contact.
The entire cell is filled with an electrolyte containing lithium salt. Both electrodes are submerged in this, and it allows lithium ions to move through between the positive and negative poles.
The internals of a solid-state cell are completely different. No flammable liquids are involved because everything inside is solid. What changes are in bold below:
You still have a cathode, and it is still made from a “standard” cathodic material like LFP, the same as a traditional cell.
The separator is made of ceramic or a solid polymer that conducts. It also acts as the electrolyte.
The anode is made of pure lithium.
Imagine filling a cardboard box with concrete, and before it dries, you stick two metal rods in it. It’s sort of like that.
These changes make a big difference. A solid-state battery is safer than a traditional Li-ion cell because there is no flammable liquid that can leak or explode under pressure. This is reason enough alone to use them, but they’re also battery batteries all-around.
They have a higher density. This means they can store more energy using the same footprint as a traditional cell. I have a 10,000 mAh portable battery pack that is actually smaller than a “regular” 5,000 mAh battery pack here on my desk. That means more life between charges without any increase in the size of your phone.
They have a longer lifespan. As lithium ions are transferred and attracted inside the electrolyte, some are deposited as solid lithium on the negative electrode. Once this happens, these particles no longer work to charge the cell. This doesn’t happen the same way in a solid-state battery, and it’s theoretically possible to get up to 45,000 charging cycles from one. That’s under the most perfect conditions, but in normal use, we can expect about double the lifespan compared to a “regular” battery.
They safely charge faster. The negative electrode is what determines the maximum safe charging time of a lithium cell. With a solid electrolyte, higher charging and discharging rates are possible without overheating or volatility, since there is no liquid electrolyte.
They work in the cold. Solid-state batteries remain efficient at low temperatures compared to standard lithium-ion cells. There is still a point where they cease to be efficient enough to operate, but you can use and charge a solid-state battery at colder temperatures.
Sounds good. Will it be in my next phone?
Probably, but not just yet. Bummer, I know.
There are a few disadvantages to solid-state batteries: they’re harder to manufacture because the anode “breathes” and slightly expands and contracts, making it harder to compress the entire package. They also still lose efficiency when the separator/electrolyte gets too cold, even if it’s not as bad as a traditional cell. Mostly, though, it’s the cost factor.
It costs more to design and build a solid-state battery, so companies making them have to charge more; changing what an electrode is made of is pretty easy, but retooling equipment to build batteries using a solid electrolyte isn’t.
We’ve reached a point where the extra cost is justified enough, but just barely. If you want your next phone to automatically cost more, the company making it can cram a solid-state battery inside, but most people don’t like that idea. Phone makers have to juggle the cost of building a device and the selling price to stay profitable.
You can already find solid-state battery packs from companies like Better Mobile Xperience. I’ve been using both their 5,000mAh and 10,000mAh batteries for a while, and they live up to the hype, but they’re not cheap.
Of course, you can expect to see them in electric vehicles and industrial applications too, but we need to give it a little more time. Once the production issues are figured out, the price will drop, and manufacturers will be inclined to use them – especially in foldables.
Just know it’s coming, and it’s better!
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