Solid state batteries are a revolutionary step forward in the field of EV’s, with its promise of making an EV having a similar fuelling pattern as an internal combustion engine vehicle. Despite this promise, solid state batteries are still not widely incorporated in EV’s. This article explains about the solid state battery, its advantages and limitations along with the companies that are indulging in its research.

What are solid state batteries?

To understand a solid state battery is, it is very important to understand how a conventional battery works. A battery usually consists of an anode and a cathode (the positive and negative sides) with an electrolyte in between. The main aim of a battery is to generate electricity which narrows down a fundamental process: generating a flow of electrons.

Once a conductive path is set up using a wire, a chemical reaction occurs in the battery that builds up electrons at the anode side. Due to this, an electrical difference is obtained between the two ends and because of this, the electrons want to rearrange themselves and get rid of this electrical difference. The only way the electrons can do that is by travelling to the cathode side, but the electrolyte acts as a hindrance. Therefore, the electrolytes are forced to travel through the wires to get to the cathode.

Now, the difference between different types of batteries is the electrolyte that is used in between the cathode and the anode. In lithium ion battery, liquid electrolytes are used as separators whereas a solid state battery uses thin layers of solid electrolytes.

Advantages of solid state batteries

The main problem with liquid lithium ion batteries is that they contain a liquid electrolyte that is flammable in nature. Therefore, for applications in EVs, these batteries pose quite a risk of catching flames during critical situations that would endanger driver and passenger life. This does not happen in case of solid state batteries.

Due to this stability, solid state batteries have a faster charging period and need less safety accompanying it. This also means that they are able to hold more energy which is very beneficial for the EV industry as a robust alternative to gasoline vehicles.

Companies indulging in solid state battery research

Due to the host of benefits solid state batteries offer, automotive have already started focusing their research in developing them. Toyota Motor Corp from Japan has already charted out its plans for developing solid state batteries by the year 2030, with the company pumping in over $13.5 billion into its battery research department.

Panasonic Corporation through its collaboration with Toyota has already pipelined the development of Powerpacks for non EV related applications.

Volkswagen, with its partnership with QuantumScape Corp has already started developing batteries having 30 percent more range than the liquid state batteries and has the ability to charge itself to 80 percent capacity in mere 12 minutes.

Some major automotive companies are also collaborating together through potential small startups for solid state battery development. Ford Motor Co and BMW AG have invested in Solid Power which claims to have developed its solid state technology to deliver 50 per cent more energy density than the current lithium ion batteries in the market.

Hyundai has also invested in a start-up called SolidEnergy Systems and is planning to develop solid-state batteries by the year 2030.

Limitations of solid state batteries

Despite the host of advantages solid state batteries offer, they are still not being mass manufactured. One of the hindrance is that due to the technology is relatively new, the complexity of scaling up the process from a lab setting has not yet been simplified.

According to a paper published in Nature nanotechnology by University of California San Diego, there are three challenges that need to be kept in mind if any company needs to scale up its solid state battery development process. These three challenges are namely:

•  Developing stable chemical interface between the electrolyte and the electrode,
•  Developing sustainable manufacturing practices for development, and
•   Placing in effective recycling practices for the residue generated while manufacturing.

Besides the development process, the other key factor is that the solid state battery needs to perform optimally at room temperature.

There’s another challenge in the form of getting the solid electrolyte material right. Several materials, ranging from ceramics such as sulphides, phosphates and oxides, to solid polymers have been solid contenders for electrolytes over the past couple of years. According to the latest research, the garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolyte has emerged to be a stable electrolyte, courtesy to its good stability and high ionic conductivity against Li.

The road ahead

Electric vehicles are going to be the future of the transportation industry. It is estimated that by the year 2030, electric vehicles on roads are expected to increase to 145 million. Due to this acceptance of electric vehicles by the public because of the host of benefits it offers, it of utmost importance for the automotive companies to develop safe and stable batteries with longer charge cycles to power them. With solid state batteries showing promise in achieving this, it is expected that majority of the electric vehicles would be powered by solid state batteries in the future.