How Solid-State Batteries Work and Why We Need Them

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We use batteries all the time. They power daily necessities like our phones, laptops, and cars. Batteries are such a fundamental part of our life that losing one or running out of charge can be catastrophic.

Everyone has experienced some frustration connected to batteries: phone batteries that die too quickly, range anxiety on electric vehicles (EVs), or even waking up late because of a dead alarm clock battery. 

Imagine phone and EV batteries that could charge in minutes and hold that charge for much longer. That’s the dream, right? Well, it might be closer to reality than you think, thanks to the technology behind a newer type of battery known as the solid-state battery. To understand what makes these so special, let’s look at how batteries work in general and how solid-state batteries work specifically.

How Do Batteries Work Anyway?

The current standard is based on a 200-year-old design featuring a positive and negative terminal, known as the cathode and anode respectively. If you’ve installed a AA battery in a TV remote, you’ve seen those + and – symbols on either end of the battery. Those mark the anode and the cathode.

If you were to open the battery up, you’d find a separator, usually made from a microporous material. In older designs, that material was usually paper, cardboard, or cloth. Today’s batteries typically use synthetic membranes like polyethylene (also known as the most used plastic in the world) and other synthetic materials.

To put it all together, the battery is filled with an electrolyte. Electrolytes commonly come in liquid form, but there are gel and paste forms that are used on smaller and more portable batteries like the AA batteries we all know. There are also solid electrolytes made out of ceramics, glass, or semi-conductors which are typically found in solid-state batteries. 

Now, how do all those parts work?

The anode (the negative terminal) produces electrons. When the battery is in use, those electrons will flow from the anode and make their way to the cathode (the positive terminal).

When we put something in between the anode and cathode, like a lightbulb, we take advantage of all those traveling ions and let them do the work.

So really, that flashlight or phone of yours is purely powered by charged particles moving from one place to another.

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It’s similar to generating electricity from hydroelectric and wind turbines but done on a microscopic scale.

What Are Lithium-Ion and Solid-State Batteries?

Our battery of choice for our gadgets and most rechargeable devices is the lithium-ion battery. The main benefit that they bring to the table is that they don’t self-discharge as much compared to other battery types.

Self-discharge is when a battery leaks some of its charge, even when it’s not in use. This is usually caused by a chemical reaction inside the battery. Most of the time, it’s just wasted energy but a high self-discharge rate can be dangerous. If it happens fast, it can lead to overheating or leaking battery acid.

Another key benefit: rechargeability. In older designs, once a battery had moved all of its electrons from one terminal to the other, it was spent. Lithium-ion batteries, on the other hand, can be charged by applying a voltage stronger than the battery itself to force the current to flow backward from the cathode to the anode.

However, early rechargeable batteries required a process called priming when you first used them. About 10 years ago, if you got a brand new phone, you might remember having to charge it for anywhere from eight to 24 hours before you could use it. That was needed to prepare the battery to operate at peak capacity.

Lithium-ion batteries eliminated the need for priming so, today, we can use our phones right out of the box.

For all its advantages, lithium-ion batteries are just not that safe. The biggest threat is fire hazard. The electrolyte used is highly flammable and if the battery overheats, is damaged, or is charged too quickly, it’s prone to exploding or bursting into flames. As the battery ages, that risk increases.

A solid-state battery essentially shares the same structure as a lithium-ion battery, with the big exception that it no longer uses a liquid-state electrolyte. It swaps that out for a solid electrolyte made from glass, ceramics, or semi-conductors.

It’s theoretically simpler in structure as you can see on the photo below, but the real challenge of solid-state batteries is for researchers to find a stable chemical composition that will bring all the benefits that solid-state batteries are promised to have.

Benefits of Solid-State Batteries

Solid-State Batteries Are Safer

The main reason lithium-ion batteries are so prone to fire is that they use a liquid electrolyte. That liquid or gel electrolyte soaks all of the components inside the battery. Because those components hold a charge and can produce sparks, submerging them in a flammable liquid is a recipe for disaster. 

You might think that as long as someone isn’t poking or stabbing the battery, everything should be fine. Well, that isn’t the case with batteries because they degrade over time. One of the things that make the degradation possible is the growth of dendrites inside the battery. Dendrites are microstructures that look a bit like trees or stalactites and form when the lithium ages and degrades. 

While dendrites are microscopic, they still produce tiny spikes that are capable of penetrating through the separator and causing a short circuit. That short-circuiting can ignite a fire. So, if you have an aging device with an aging battery, your device might just be one dendrite growth away from self-destructing.

Dendrite growth is still a problem with the solid-state batteries currently in development, but the threat is lower and the future with solid-state batteries will still be a future without batteries spontaneously combusting. 

Another bad thing about lithium-ion batteries is that they need a lot of care when it comes to designing and manufacturing them. Lithium-ion batteries need a dedicated built-in circuit for voltage and current protection to ensure proper use.

Do you remember when Samsung Note 7 phones started to explode back in 2016? Those cases were all caused by a tiny manufacturing defect that made the battery vulnerable to exploding.

The manufacturing process of the battery left a defect that bends or deflects the negative electrodes near the edges of the battery which then causes a short circuit. And with the flammable liquid electrolytes inside the battery, you know what comes next. 

While the bulk of the blame is definitely on Samsung and its manufacturing partners, I think the lithium-ion battery design is also part of the problem. If it wasn’t so prone to fire, such a minor defect might not have resulted in so many explosions.

The solid-state battery will be much safer than this because every component is made from solid materials which should be more resilient and less prone to short circuits. Most importantly, there won’t be any flammable electrolytes to catch fire in the event of a short circuit. 

Solid-State Batteries Hold More Charge and Charge Faster

The biggest reason electric cars are just not viable for a lot of people is that they take a long time to charge for very little range. The fastest-charging Tesla available today charges from 0-80% in around an hour. Meanwhile, filling up your gas tank to 80% takes about five minutes at its slowest.

Electric vehicles using solid-state batteries will be much more practical. The goal is to design an EV-sized battery that can charge from 0-80% in around 10 minutes. While I doubt those fast charging times will be a reality before 2030, even achieving charging times of under 20 minutes would be enough to make EVs a more viable option for most people.

Phones and Laptops are also getting held back by our current battery tech. Phones in our day are already extremely advanced as it is, and with that, they use a lot more energy than before. With existing lithium-ion technology, that means building bigger batteries to power that advanced performance. Not only is that harmful for the environment, but there’s a limit on how big you can make a battery and still offer the compact, portable designs we expect. I mean, take a look at the battery size of this iPhone 12 Pro Max:

With all the high-end tech lodged into phones these days, you can’t expect a large battery anymore. For those companies that put a large battery in their phones, that’s also just making the threat of a fire hazard even worse.

With solid-state batteries, companies will be able to make smaller batteries while still getting the same or better performance. And the best part? Since the battery will be smaller, phones will have more space to put more cutting-edge components like bigger and better cameras, larger motherboards, and more!

Solid-State Batteries Are Greener

Most of the world agreed to become greener by 2030 or 2050. To do that, we will have to ditch lithium-ion and disposable batteries on our mass-produced devices.

Why? Well, lithium-ion batteries need metals like lithium and cobalt. Lithium and cobalt mining does a lot of damage to the environment by blowing up mountains and contaminating water.

Not to mention, lithium and cobalt mining are known hotspots for modern slavery and child labor, so yeah, current EVs are not only as green as you might think, they might even also come with some blood.  

But the biggest problem with lithium-ion batteries is that they’re extremely hard to recycle. Their complex structure makes recycling them a hard and tedious task. As a result, little to no lithium-ion and alkaline batteries are getting recycled.

When they aren’t recycled, those batteries along with their flammable electrolytes and harmful acids generally end up on landfills where they end up leaking into soil and other trash. That leakage could cause a fire and even poison the groundwater.

Of course, solid-state batteries will still need a lot of mining to be done since they’ll use a lot more semiconductors, glass, ceramics, lithium, cobalt, and other precious metals. But here’s why solid-state batteries are still better:

They will be a lot easier to recycle since everything is made of solid materials.

Plus, unlike lithium-ion batteries, SSBs can hold 90% of their total charge capacity even after 5,000 charge cycles. My six-year-old laptop has 1,200 charge cycles and it doesn’t even last two hours now. That’ll simply mean that SSBs will hold their charge even after 10-15 years!

So as time passes, less and less mining will be needed because batteries will last longer and we’ll be able to recycle materials from old SSBs rather than mine new materials. Lastly, Solid-State Batteries can also be 3D-Printed which can significantly reduce manufacturing waste.

When Can We Expect SSBs?

Solid-state batteries actually exist right now. The ones being used are small, low-powered batteries typically found in pacemakers, RFID devices, and a handful of wearable devices.

But, the real question that everyone asks is “When can we get solid-state batteries on EVs and smart devices?” The short answer is about 5-10 years. Solid Power aims to start producing 100-ampere battery cells this year that will be used to power Ford’s and BMW’s vehicles by 2027. Likewise, Toyota partnered with Panasonic to work on solid-state batteries that should power Toyota’s EVs by 2025-2030. Of course, take any prediction with a grain of salt.

As of now, most solid-state batteries in development are still growing a lot of dendrites which causes the solid-electrolytes to crack. The goal is to discover or make a stable chemical composition that enables these solid-state batteries to hold a longer charge, charge faster, be safer, and be more sustainable.

But, solid-state batteries could help us move toward a world full of truly eco-friendly EVs and better storage capacity for renewable energy. These batteries aren’t just a technological breakthrough. They contain hope for a better tomorrow.