Solid-state Battery Breakthrough Could Double EV Range
Electronics giant Samsung has made an important step towards making solid-state batteries a viable tech for electric cars - meaning longer ranges for electric vehicle (EV) owners.
Samsung’s Advanced Institute of Technology (SAIT) claims the chemical breakthrough means the size of the battery is halved, so you could theoretically double the range of today's first-generation EVs, from around 200-300 miles to nearer 400-600 on one charge.
The secret to Samsung’s super battery lies in its electrolyte. In conventional EV batteries, the electrolyte is a liquid, but Samsung’s scientists and engineers have developed solid electrolyte technology, which is far denser than the liquid approach.
Master at SAIT’s Next Generation Battery Lab and the leader of the project, Dongmin Im, said: 'The product of this study could be a seed technology for safer, high-performance batteries of the future. Going forward, we will continue to develop and refine all-solid-state battery materials and manufacturing technologies to help take EV battery innovation to the next level.'
Boosting energy density by a claimed factor of three, Samsung's prototype solid-state batteries introduce a new silver-carbon coating known as Ag-C, which is just 5.0 micrometers thick. This Ag-C nanocomposite not only allows more compact packaging but resists the growth of ‘dendrites’ - the chemical formation of needle-like crystals which reduces battery capacity over many charge cycles, as well as the stability of the pack.
Samsung says they can be recharged more than 1000 times (about half a million miles of total range) for a future of more attractive and compelling electric vehicles.
Solid-state batteries for electric cars: the next big thing?
Electric cars are improving constantly in terms of mileage, performance and charging time – but there’s still a lot of room for improvement. While the number of hybrid cars is only likely to increase, fully-electric vehicles aren’t quite ready overtake the internal combustion engine.
That’s because most EVs and hybrids rely on electric motors powered by lithium-ion batteries, using the same tech that powers smartphones and laptops. Essentially an evolution on chemical batteries, lithium-ion batteries work well in EVs, but there are better solutions.
The use of a liquid electrolyte in lithium-ion batteries comes with a suite of disadvantages. Capacity and ability to deliver peak charge deteriorates over time and lithium-ion batteries also bleed a lot of heat, requiring weighty cooling systems to be integrated into their design. And thanks to the flammable liquid they contain, lithium-ion batteries can catch fire or even explode if damaged in an accident.
For the last few years, car makers have begun to mention solid state batteries as the next breakthrough EVs, usually quoting insane performance and range at the same time. So, what makes solid-state battery tech so good for EVs, how does it work – or is it just a bunch of vapourware?
What are solid-state batteries?
Simply put, solid-state batteries use a solid electrolyte as opposed to the liquid or polymer gel one found in current lithium-ion batteries, and it can take the form of ceramics, glass, sulphites or solid polymers.
olid electrolyte aside, solid-state batteries function much like those in lithium-ion batteries, in that they contain electrodes (cathodes and anodes) separated by an electrolyte that allows charged ions to pass through it.
How do solid state batteries work?
Much the same way as a normal battery, if we’re honest. The flow of ions trigger a chemical reaction between the battery’s materials called ‘Redox’ where, when discharging power, oxidation occurs at the anode to create compounds with free electrons, which deliver electric energy, and reduction at the cathode which sees compounds gain electrons and thus store power. When a battery is charged the process is reversed.
Much like lithium-ion batteries, when delivering power in solid-state batteries, aka discharging, positively charged ions travel through the electrolyte from the negative electrode (anode) to the positive one (cathode). This leads to a build up of positive charge in the cathode which attracts electrons from the anode. But as the electrons can’t travel through the electrolyte they have to travel across a circuit and thus deliver power to whatever it’s connected to, say an electric motor.
During charging, the opposite happens with ions flowing to the anode building up a charge that sees electrons pulled to it across a circuit from the cathode. When no more ions will flow to the negative electrode, the battery is considered fully charged.
Solid-state batteries have been around for a while, but are only used for small electronic devices like RFID tags and pacemakers and in their current state are non-rechargeable. As such, work is being done to allow them to power larger devices and be recharged.
What makes solid-state batteries the next big thing?
Thanks to the solid electrolyte having a smaller footprint, solid-state batteries promise some two to ten times the energy density of lithium-ion batteries of the same size. That means more powerful batteries without extra space, or more compact battery packs without compromising on power. That means powerful and longer range electric cars or more compact and lighter EVs. They are also expected to charge faster.
Better efficiency and energy density means solid-state batteries don't require the cooling and control components that lithium-ion batteries do either, and that means a smaller overall footprint along with more chassis freedom and less weight. It’s little wonder that solid state is most quoted by performance car manufacturers; Bentley sees the technology as its primary way to make electrification work for them.
Safety is another advantage solid-state batteries claim to offer. Exothermic reactions in lithium-ion batteries can cause them to get hot, expand and potentially rupture spilling flammable and hazardous liquid electrolyte; in some cases this has caused minor explosions. Having a solid electrolyte effectively bypasses this problem.
Finally, the use of the solid-state electrolyte means the batteries can withstand more discharge and charge cycles than lithium-ion batteries, as they don’t have to suffer electrode corrosion caused by chemicals in the liquid electrolyte or the build up of solid layers in the electrolyte that deteriorates battery life. Solid-state batteries could be re-charged up to seven times more, giving them a potential lifespan of ten years as opposed to the couple of years a lithium-ion battery is expected to effectively last for.