What are Solid State Batteries?

With the advancement in technology day by day the electric batteries are also getting more and more advanced today. We have developed Li-ion batteries from older technologies batteries. And now the world is moving towards solid state battery which is far more batter than the li-ion battery in terms of safety, life span, and energy density.

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So what are basically solid state batteries? How is it different than the older generation batteries and the li-ion batteries? The history behind solid state battery, electrolyte used in it, benefits of these batteries over li-ion battery and which companies at present are manufacturing it. We are going to discuss everything related to solid state batteries in this post.

History of Solid State Batteries

Michael Faraday, the father of electricity and famous for his discovery of electromagnetic induction, discovered solid electrolytes silver sulfide and lead(II) fluoride for the first time. His discovery made a foundation for the development of solid state batteries.

In the early 20th century, researchers started to experiment using solid electrolytes in batteries. In 1970 researchers started developing solid state batteries which replaced the traditional liquid electrolyte batteries. However these solid state batteries does not come into use because it had a lot of issues related to energy density and life spans. These solid electrolytes had limited energy density and shorter life span thus can not be used commercially.

Since all these issues can not be solved at that time the existence solid state batteries get lost. And now we are using the liquid li-ion batteries. But with the great research and better development in technology the concept of solid state batteries is back again. Researchers have successfully developed solid state battery with different manufacturing techniques.

In 2011, the first solid electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) was demonstrated by Kamaya et al. which is a great achievement in field of electric automobiles.

It has solved all the issues that were present in the older solid state batteries. The new manufacturing technique, roll-to-roll processing, speed up its production on larger scale at lower cost.

What is solid State Batteries?

Solid state battery is not a new concept. It started in early 20s and now getting popular due to several advantages. A type of rechargeable battery which uses solid electrolyte instead of liquid is known as solid state battery. The traditional batteries uses liquid electrolytes based on application and performance such as:

Type of BatteryElectrolytes Used
Lithium-ion batterymixture of lithium salts dissolved in organic solvent (ethylene carbonate or propylene carbonate)
Lithium-polymer batterypolymer material such as a polyethylene oxide
Sodium-ion batterysodium salt dissolved in organic solvent
Lead-acid batterysulfuric acid (H2SO4)
Zinc-carbon batterymixture of zinc chloride and ammonium chloride
Electrolytes used in different types of batteries

Normally, li-ion batteries have a negative side anode, positive side cathode, liquid electrolyte and a separator. The flow of ions in between the cathode and anode through electrolyte during charging and discharging produces electricity. The electricity thus produced powers the battery.

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The electrolyte used in such batteries is liquid. But in case of solid state batteries solid electrolytes are used. This a great revolution in the field of science and technology. Solid state batteries have more energy density in comparison of liquid electrolytes batteries.

Like in li-ion battery, solid electrolytes conduct ions between anode and cathode to generate electricity. Such electrolytes includes ceramics, polymers, glass. The use of electrolytes depends on the use and performance required. For instance, ceramics lithium super ionic conductors (LISICONs) can tolerate high temperature thus used in such conditions. Unlike ceramics, polymers are used in lower temperature applications.

The cathode and anode materials is plays a crucial role in the performance of the battery. High-capacity lithium metal anodes are used along with solid electrolytes. Manufacturing process of the battery also determines its quality. Several technologies such as roll-to-roll technology as mentioned earlier helps to produce batteries in larger scale in less time.

How is solid state batteries made?

Manufacturing of solid state batteries go through a series of steps as described in the table below:

  • First of all the materials for the electrolyte is prepared. It is prepared using various methods. The method to be used depend on the type of solid electrolyte to be produced.
  • After the preparation of electrolyte the process goes for the preparation of electrodes. The materials of cathode and anode is prepared. Lithium is used for the manufacturing of electrode. Thus produced electrode is characterized on the basis of their capacity and conductivity.
  • Thus produced solid electrolyte and the electrodes(cathode and anode) are assembled in a cell. The cathode and anode is placed in layer. In between the cathode and anode solid electrolyte is placed. After everything is assembled it is sealed in order to prevent from external factors such as air and moisture.
  • Now its time to check the performance of the battery whether it is working or not. Testing help to assure the capacity of the cell and also help to redesign the cell.
  • After all the process production, assembling and testing is done successfully the company focuses on the mass production. For production in a large quantity different techniques like roll-to-roll or screen printing are used.

What are the benefits of solid state batteries ?

In the timeline of evolution of electric batteries the traditional batteries were evolved into advanced li-ion battery. And now the liquid electrolytes li-ion battery are getting changed into solid electrolytes battery. It has several advantages over the liquid electrolyte battery. Some of them are described as:

1. Higher energy density

Solid state batteries have higher density than the liquid electrolytes battery. Since solid are more compact in comparison to liquid they can store more energy in smaller space. This increases the density of the battery.

2. Provides more safety

Everyday we hear different news regarding the fire accidents in electric vehicles. Even some of the evs get fatal accidents and people have to sacrifice their life. The li-ion battery contains all the elements such as oxygen, flammable organic solvents which can self sustain fire.

While solid state batteries have non-flammable electrolytes which restricts fire accidents. There is no any partition between anode and cathode in li-ion battery so they directly get contact with each other through electrolyte. This leads to short circuit.

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