Solid-State Batteries – a revolutionary technology, or just another over-hyped product?

Solid State Batteries

You’ve probably seen news on this ‘revolutionary battery technology’ recently if you are even remotely interested in this industry. It really is hard to miss. It’s called solid-state battery technology, but you may have heard the term ‘dry electrode’ thrown about a bit with Tesla’s acquisition of Maxwell technologies.

However, dry-electrode batteries shouldn’t be confused with solid state batteries, they’re different. I’ll cover that in another article.

It really does sound convincing, with claims of up to ‘double the range’, ‘significantly better durability’ and ‘faster charge times. However, is this technology really the future? Is it feasible to implement it to the mass market? How much research needs to be done?

What are solid-state batteries?

On the surface, this looks relatively complex, but it’s core principle is quite simple. In the following few chapters, I will try to break it down as simply as I can.

At it’s core, ‘solid-state’ just means ‘no moving parts’. For example, you may have a solid-state drive (SSD) in the computer or mobile device you are watching this on. Basically, it has no moving parts, compared to the traditional hard drive which has a spinning platter and a head.

Because it has no moving parts, it is more reliable and is quicker too as everything is digital. This is important as it applies to what we are learning about batteries in just a moment.

How do they work?

Let’s start by taking a journey, through some of the earlier generations of batteries. Don’t worry, I’ll make it brief!

So we start with the alkaline battery – it’s what you will most commonly see in smoke alarms, remote controls and wireless mice and keyboards. They are popular, accounting for 80% of manufactured batteries in the US. Contrasting to the zinc-carbon batteries with acidic electrolytes (the liquid in the battery that the current flows through), alkaline batteries have an alkaline electrolyte, hence the name.

Fortunately, some of these are rechargeable. A process which involves passing an electric current through them, causing the chemical reaction which releases energy to be reversed.

Next, the lithium-ion batteries – these are most commonly found in smartphones, model aircraft or drones, and current electric cars of course! These are rechargeable and they release energy by creating a flow of lithium ions from the negative to positive electrodes. Tesla’s gigafactory currently produces more of these than the rest of the world combined, thanks partly to a collaboration with Panasonic.

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Lithium ion cell on the left and a solid-state cell on the right

Now we come to solid state batteries, as you can see in the diagram above, they are smaller. What you are seeing is one of the many advantages of this battery type, size. We can attribute this to the solid electrolyte.

At this point, you’re probably wondering how the ions are able to move through something solid. That’s because when the battery is charged or discharged, ions flow through an ion-conductive solid matrix, the solid electrolyte.

What are the advantages of solid-state batteries?

Because they have a solid electrolyte, this allows them to be smaller, whilst still packing in similar amounts of energy. This means more can be packed into a smaller space, resulting in more range for electric cars, or more battery life for smartphones.

There’s a lot of concern about electric cars catching fire, this is mainly attributed to the fact that it is new technology. Hopefully, this concern could be killed by the use of solid-state batteries. The reason for this is that solid electrolytes help to prevent dendrites forming.

What on earth are dendrites? Well, they’re threaded like projections from plated metal. Occasionally, they can grow so much that they connect the electrodes, short-circuiting the battery and getting very hot.

Unfortunately, this may cause the battery to catch fire, so it’s probably better to try to get rid of them. Solid-state electrolytes can ‘push down’ on the plated electrodes, stopping any dendrites from forming by creating a smooth surface.

Life Expectancy

Solid electrolytes help batteries to last longer too! When first charging a standard lithium-ion battery (which you were introduced to earlier), a reaction takes place between the lithium electrolyte and the carbon electrode. The purpose of this is well-intentioned, to protect the carbon electrode from disintegrating.

Consequently, the durability of the battery is determined by the very thin layer which forms on the electrode (called the solid-electrolyte interference layer). In a solid-state battery, this layer does not form so the durability of the battery does not depend on it. As a result, the batteries are more durable.

You may be convinced already, but you’ve only heard one side.

As with most new technologies, there are drawbacks and flaws. One of these is the cost. In 2012, it was estimated that a 20 Ah (ampere hour) cell would cost the US $100,000 to make.

Since electric cars need about 800-1000 of these cells, the total cost would be $80,000,000 to $100,000,000. Just for the battery pack! That’s colossal, though that was in 2012 and technology has improved lots since then.

Additionally, solid-state batteries are though to perform poorly in low temperatures. Problematic in places like Norway or Sweden where there are lots of electric vehicle owners and temperatures are far below zero in the winter.

Conclusion – are they worth it?

In conclusion, there are many advantages and drawbacks. On the other hand, there’s potential for the advantages to be made better and the drawbacks being eliminated.

It’s a great technology, and if we could leverage it’s full potential, it could be ground-breaking for the future of batteries. Not only in electric vehicles, but in energy storage, mobile phones and many more cases.

So then, are they worth spending vast amounts of research funding on?

Yes, definitely. Even if they are not suitable, we are bound to learn something new and useful from them. And if they are suitable, we could be experiencing 500-mile range vehicles within a decade. What if we could utilize this technology in Tesla powerwalls? That’s the type of thing which makes the future exciting!

Finally, if you’ve got any questions about this new technology, I welcome you to leave a comment in the section provided below this article. Alternatively, you could use my contact page for any questions or queries.

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