Solid State Batteries

Back in 1991, Sony introduced us all to the first commercial lithium-ion battery when they used it to provide power for one of their new-fangled camcorders. The technology caught on rather well, as I’m sure you know, and nowadays lithium-ion batteries are in just about every conceivable electronic device, from calculators to electric vehicles. They’ve even carved out a niche in very large grid-scale energy storage.

But according to most industry commentators, lithium-ion batteries are not the final answer to the energy storage question. Next-generation batteries will need to find a way of improving energy density, reducing charging time, and lengthening battery life while also eliminating the slightly inconvenient potential hazard of spontaneous combustion that existing lithium-ion batteries can suffer from.

The answer to that conundrum, according to most industry experts, will be solid-state batteries. But it’s a technology that’s not generally expected to come to market until the latter part of this decade at the very earliest.

At least that was the accepted wisdom until recently. Now though, a large and very well-established Japanese battery and supercapacitor maker called Murata has announced it will begin mass-producing a market-ready all-solid-state battery by the Autumn of 2021.

So have they really stolen a march on the competition, or will this be yet another empty battery promise? There’s an awful lot of industry and media excitement around solid-state batteries at the moment.

Well, to be more accurate, there’s been an awful lot of industry and media excitement around solid-state batteries for about the last decade or so.

But it seems that every time a major manufacturer announces they’re on the cusp of a breakthrough, with promises of real-world production runs within months, their optimism turns out to have been unfounded, and their plans for solid-state technology are quietly put on a back burner.

It happened with Fisker, who originally promised a supercar powered by a solid-state battery by 2020 then said it would be delayed until 2022, and now they’ve dropped the idea altogether.

It happened with Dyson, who bought a Michigan-based solid-state battery company called Satki 3 in 2015 and spent billions developing its own electric vehicle before canning the project altogether, writing off all that investment capital, and parting ways with Satki 3’s founder, Marie Sastry, in 2017.

The list of companies vying to be the first to market with a workable solid-state battery is lengthy, but none of them look like getting anything into real-world production until 2025 at the very earliest.

So why is that? Well, it turns out that solid-state batteries are proving to be devilishly difficult things to develop. However, the basic principle seems straightforward enough and looks very attractive when compared directly to a traditional lithium-ion battery.

Lithium-ion technology makes use of an electrochemical reaction. Inside each battery, there are two electrodes – a negatively charged anode, typically made of graphite, and a positively charged cathode made of some combination of lithium and other elements.

The two electrodes are separated by a liquid electrolyte solution with a semi-permeable membrane in the center, acting as a separator between negative and positive. Electrons flow from the cathode out across the external power source and back to the anode as the battery charges up.

That causes the cathode to release its lithium ions, which move to the anode by flowing across the electrolyte and passing through the semi-permeable membrane. When a fully charged lithium-ion battery is connected up to a device, electrons flow out from the anode through the connected device and back to the cathode, causing the lithium ions to flow back across the electrolyte.

Once all the ions have made that journey, electrons stop flowing and you’ve got a flat battery. Lithium-ion batteries are an attractive option because lithium is the most electropositive element, which means it very easily gives up its negative electrons to produce positive ions lithium.

It’s also the lightest of all the metals, so lithium-ion batteries are much lighter than lead-acid batteries and have a much higher energy density. Those are extremely useful qualities whether you’re making a mobile phone or an electric vehicle, but the useful reactivity of lithium also has its downside.

No doubt you’ve heard of the dreaded dendrite issue for example. Over time, deposits of lithium ions can build upon the face of the anode forming spikes that can eventually puncture the separator.

Suppose they manage to get all the way across to the cathode. In that case, you get a short circuit – an instant discharge of a very reactive material into a volatile and highly flammable liquid electrolyte, which is something you definitely don’t want.

The result could be a nasty swollen battery pouch that has to be replaced, or if you’re really unlucky, you could find yourself with a small incendiary device going off in your trouser pocket.

Solid-state batteries remove that problem by using a solid electrolyte instead of liquid, hence the name. That makes the whole battery much safer. It also makes it much more compact with a much higher energy density – perhaps as much as three times that of a standard lithium-ion battery.

Solid-state batteries can work at very high rates of power as well. Research suggests that they may be capable of recharging up to six times faster than current technologies and achieve far more charging cycles during their useful working life – something that electric vehicle makers are particularly interested in for obvious reasons.

And because they don’t have that volatile and highly flammable liquid electrolyte, they no longer need the cumbersome battery management systems that add weight and cost to existing lithium-ion batteries.

They’ve actually been in existence for longer than you might think. They first got used in pacemakers for heart patients way back in the 1970s. A sheet of lithium metal is placed in direct contact with solid iodine.

That effectively causes a short circuit and forms a new layer of lithium iodide between them. Once that layer is formed a tiny, but constant current can still flow from the lithium anode to the iodine cathode for several years, making it ideal for keeping a dodgy ticker beating reliably.

In 2011, Toyota made a breakthrough with a solid sulfide based material that had the same ionic conductivity as a liquid electrolyte, and ever since then, the race has been on to perfect the technology.

It’s proven to be a technically very difficult challenge. Studies on sulfides for electric vehicle batteries have suggested that if the battery packs were breached in some way and the sulfide escaped, it’d produce a very unhealthy gas when exposed to air.

Getting them wet is apparently another problem too, as one Toyota engineer recently pointed out, “materials for all-solid-state batteries don’t go well with water”. He said, “it’s difficult to maintain a dry state in a plant and other facilities”.

Murata’s battery doesn’t use sulfides in its chemistry, and it’s not aimed at the electric vehicle market. Instead, it’ll sit in the space somewhere between tiny devices like pacemakers and mobile devices like smartphones.

That space is currently occupied by wearable technology like earphones and another internet of things or IoT devices that are rapidly being developed. In 2017 the company acquired Sony’s battery division, and since then, they’ve managed to combine Sony’s sophisticated lithium-ion battery technology with laminating techniques they’d already developed to make their own multi-layered ceramic capacitors.

The result is a battery with a non-combustible and highly heat resistant solid oxide ceramic electrolyte, which Murata claim has a substantially larger capacity than any previously developed technology.

The Japanese firm will establish a production line for the batteries at its Yasu division in Shiga prefecture in Japan and commence production in the autumn of 2021, starting with relatively small batches and eventually building to a capacity of a hundred thousand batteries a month.

This is a pretty bold move for Murata. They’re sinking a huge amount of upfront capital into the project and will almost certainly make no profit on the product for some time, but they see it as an essential step forward to try and stay ahead of the pack in what is rapidly becoming an extremely competitive playing field, with huge industry players in China, South Korea, the United States and Europe all desperately trying to gain market supremacy.

The real holy grail, though, the tantalizingly elusive megabucks goal that keeps all major R&D departments furiously working away all over the world, is of course, a truly affordable, mass-produced, solid-state battery for electric vehicles.

Suppose such a thing ever comes to market. In that case, it’ll be so disruptive to the auto industry that it’ll most likely accelerate the demise of internal combustion engines and really kick-start the revolution of fossil-free global transport.

Not difficult to see why it’s such an enticing prize, but putting the corporate head above a well-targeted public parapet has so far proven to be a dangerous and costly gamble, and not just for Fisker and Dyson either.

The US battery maker Quantumscape has also fallen foul of its own ambition recently. The company has been widely touted as the most likely contender in the pioneering world of solid-state batteries.

In November 2020, the business was floated on the New York stock exchange to great acclaim. They announced that they created fire-resistant test batteries that were good for 80% capacity even after 1100 cycles.

That translates to a 300-mile battery pack with an operational lifetime of 300,000 miles, or a 500-mile battery pack that’s good for half a million miles. It all sounded absolutely splendid, and the stock price lept up by 256% in just one month.

Bill Gates invested, and the word on the street was that Quantumscape was poised to become one of the most valuable stocks in the auto industry, even rivaling Tesla. But then, an independent report was published on a crowd-sourced financial information platform called Seeking Alpha.

It suggested that Quantumscape’s batteries were actually smaller than an iWatch battery and had never been tested outside a lab. The report concluded that the batteries were unlikely to ever achieve the performance the company claimed.

That news didn’t sit well with investors, and the stock price promptly dropped off a cliff. However, despite insisting that the Seeking Alpha story had no merit, Quantumscape did have to concede that their batteries are still in the development stage, with results so far coming only from tests on small prototypes, not full packs.

They’re now facing a class-action lawsuit from a New York law firm on behalf of very disgruntled investors who’ve watched their shares drop 70% in value in recent months.

Toyota has been at the forefront of solid-state battery development ever since that 2011 sulfide breakthrough I mentioned earlier.

They’ve got over a thousand patents involving solid-state batteries, and right now, they’re looking like they might just be the first to market in the EV sector. The Japanese government has been encouraging the domestic development of solid-state batteries as part of a 19 billion dollar state fund designed to fast-track decarbonization technologies.

Toyota is planning to launch a prototype solid-state battery-powered electric vehicle before the end of 2021 and a full production model with a 10-minute charge time and 500-mile range just a couple of years later.

The likes of Nissan, VW, and Hyundai are all fairly close behind as well, and even behemoths like Ford and GM are now diving into the technology, partnering with existing battery tech companies in a desperate attempt to catch up.

There’s an old cliche, used somewhat cynically about another potentially world-changing technology, nuclear fusion. They say it’s only 30 years away from reality and always will be!

Let’s hope the same satire won’t be directed at solid-state batteries because if someone does actually nail it, then the road to global decarbonization will suddenly look a lot less long and winding.

So what’s your view? Do you think solid-state batteries are a realistic prospect or just more media hype from the big automakers?