For quite a few years now, electric vehicles have revolutionized the automobile sector, with the hope of taking the world to a greener future. While many companies have tried out different techniques and designs, one thing that has remained common is the heart of these EVs – the lithium-ion batteries. Despite many advancements in battery technology, reliability and safety are still some of the major concerns of electric automakers. With a limited optimum working range, lithium-ion cells tend to become hazardous at a higher temperature, causing thermal runaway which can damage critical components of the vehicle.
Solid-State Batteries: Future Scope Or False Hope?
One of the alternatives for this has been Solid-State Batteries, which is an area that many major battery manufacturers are working on. While many experts claim that SSBs are just around the corner, Sila Nanotechnologies CEO Gene Berdichevsky claims that there are lots of changes that the current SSB technology needs to go through before becoming viable.
One of the major reasons for the harmful tendency of lithium-ion cells is a liquid electrolyte. It tends to react faster at high temperatures and can lead to unavoidable changes in the battery, that can be hazardous. Due to this, most lithium-ion battery packs need to have extra thermal monitoring and management systems, which lead to an increase in the cost and weight of the battery. Both of these parameters are currently holding electric mobility back in its battle against internal combustion engines. Solid-State Batteries aim to eliminate this problem through the use of a solid electrolyte.
Using sulfides (inorganic) or polymers (organic) as a base material for the electrolyte eradicates this problem at its very root. These solid electrolytes are not flammable like those in lithium-ion cells are, and this could solve the problem of short useful life of cells. SSBs also display other performance facets such as a higher charging rate, increased energy density and lower tendency of current leakage. Solid Power is one of the companies deeply invested in SSB technology. They claim that SSBs could be introduced at a basic level of usage as early as 2021, while further developments in the current technology could help integrate them in automobiles by 2026.
But Is It Actually Feasible?
According to a paper written by Gene Berdichevsky and Gleb Yushin (co-founder of Sila Nanotechnologies), solid-state batteries will face several technical difficulties that will be very challenging to overcome. Dendrite formation is one of the major issues, with lithium dendrites getting formed in the solid electrolyte as well, causing short circuit. While lots of research is going on regarding this dendrite growth, very few scientists have managed to successfully review its mechanism.
In some cases, due to the uneven charge distribution in a solid electrolyte, dendrite formation causes more problems than in liquid electrolytes. Apart from this, micro-cracking of the solid electrolyte can take place due to anode expansion in SSBs, which can reduce the battery life. These are problems that are located at some of the most fundamental regions of the SSB technology, and so, Berdichevsky claims that it will be hard to tackle them. While the future may hold the practical use of solid electrolytes, it makes no sense to rush this technology into the market without further study, as they are supposed to improve reliability, not decrease it.
Are Li-ion Batteries Safe Until SSBs Come?
Berdichevsky went on to describe his vision of the future in electric vehicles and mentioned that in 5 to 10 years, Li-ion cells will cost $50 per kWh, which is much lesser than the current cost of $150-200. Apart from the cost, these batteries will also improve in performance, with figures such as 10,000 cycles, 1 million+ miles, and a 30-year life very much feasible.
Of course, today’s Li-ion cell technology will also have to change to adhere to future requirements. The American company has predicted that battery technology will see the biggest innovation growth in the coming 10 years, and the period from 2030 to 2050 will see huge scaling of this innovation to stay in line with the ever-growing demand for reliable batteries. In their words, ‘The first linchpin for Advanced Li-ion will be the Silicon Anode’. The silicon anode is projected to replace graphite entirely and will be designed to overcome swelling challenges. It can also be scaled to millions of tons at a low cost and will bring in a number of key changes to the current battery design as well. Using iron and copper cathodes, ceramic separators and advanced liquid electrolytes will all help in creating safe Li-ion technology.
What Solid Power Aims To Bring To The Market
Solid Power is creating a solid electrolyte that is based on sulfides and has high conductivity combined with excellent compatibility between anode and cathode. They are pretty sure that SSBs will have up to 50% more energy density than Li-ion cells, and this number could go up in the future. The product that Solid Power is bringing to the market is a glass-ceramic electrolyte based on a sulfide material. They also claim that the electrolyte micro-cracking problem can be solved by introducing some amount of compliance and pressure inside the cell, which will allow the anode some space during heavy operation. With a much higher range of optimal working temperatures, cell-level thermal management will not be required, thus reducing cost and weight.
While a basic battery management system will be required initially for battery pre-heating for fast charging, even this can be eliminated in the future. Solid Power is currently hoping to manufacture the all-solid-state batteries to test them for reliability first, and longevity next. Once they reach an automative level of battery performance, they are hoping to integrate these batteries in electric vehicles in partnership with industrial automakers. They are already working with BMW and Ford on the current SSB technology.
Whether the electric mobility sector sticks to Li-ion cells with its advancements in silicon anodes or does it turn to Solid-State Batteries, remains to be seen. One thing is for sure though. Be it solid electrolyte or advanced liquid, better-performing batteries are coming, which will be long-lasting, reliable, safe, and above all, inexpensive.