Battery Technology used in Electric Vehicles

With rise in environmental concerns and search for reducing the dependency on natural resources, the energy sector is revolutionising from non-renewable energy to renewable energy. Increased spending on R&D for renewable energy has evolved the generation of electricity from mechanical generation to chemical generated electricity. In mechanical transformation, the electricity was generated by rotating the turbine and converting the electromagnetic energy, for example a hydroelectric plant. In chemical conversion, certain chemicals are used in a mixture to derive electric energy from the reaction, for example lead acid batteries. 

Batteries can be classified on their properties of

• Energy density
• Charge retention
• Safety standards
• Charging time
• Cost

Batteries are small chemical reactors which generate electricity from the chemicals present in it. Alessandro Volta in 1800 was the one who put together the first battery called Voltaic pile. The voltaic pile was a stack of zinc and copper disc on one another which were separated by cloth soaked in brine (electrolyte). The current was generated with a chemical reaction. This breakthrough led to extensive research in battery technology and development of dry cell batteries, however the research was limited as the cells had one time life and couldn’t be rechargeable.

 Domestic companies manufacturing dry cell batteries are Eveready industries limited, Panasonic energy india limited, Indo national limited and others.The usage of dry cell batteries are into daily application of small electrical appliances with AA and AAA sizes. The product is in commodity business and the price maker in industry will have the highest market. 

Eveready batteries dominate the dry cell market with 50% market share followed by indo national and panasonic industries. The companies are least likely to enter into lithium battery chemistry but may provide the lithium pellets to battery manufacturers. 

Research on rechargeable batteries gave rise to the lead acid batteries in 1859 made by Gaston plante. By the end of 1880’s, lead acid batteries were extensively used in IC engine cars. The lead acid battery has high energy density with high charge retention and is cheaper compared to lithium batteries, however due to longer charging hours they could not be used in electric vehicles. Domestic companies which are manufacturing lead acid batteries are Exide industries limited, Amara raja batteries limited. The company is further leveraging their position into the lithium battery segments. The industry is highly driven by growth in the automotive industry as lead acid batteries have the highest application in the auto OEM industry.

With the introduction of lithium ion batteries in 1991 by Sony, the industry experienced a sudden surge in shift from lead acid batteries to lithium batteries. Lithium acid batteries were highly accepted because of high retention of charge, high energy density, shorter period of charge time and free of maintenance. However, lithium ion batteries are expensive to manufacture because of low availability of raw materials like lithium salts, cobalt and nickel.

Lithium deposits are largely found in Argentina, Bolivia, Chile, Australia, China and the USA.

Lithium is a highly reactive element and being the lightest metal. The high electro positivity of the element makes it most suitable for use in battery chemistry. Multiple lithium-ion cells connect internally to make up a lithium-ion battery. Think of lithium-ion cells as the building blocks that make up a full battery. These cells are connected in series or parallel and are monitored by the battery management systems. Lithium ion cell have 4 basic components 

• Body/container
• Cathode and anode
• Electrolyte solution
• Separator film

Body/ container is the outer structure of the battery which holds the cells in position and avoids its interaction with the environment. The casing has to be strong enough to withstand shocks and impacts because if it breaks and the cell gets exposed,  the solution inside the cell will react with atmospheric oxygen leading to an explosion.

Anode is the negative electrode in a cell. The most popular material used for the anode is graphite. The positive side is called the cathode. Common materials for the cathode are lithium cobalt oxide, lithium iron phosphate, and lithium manganese oxide. 

Electrolyte solution is where the actual chemistry lies,Electrolyte is a media that conducts ions between the electrodes in the cell and every composition is different for different geographies. The electrolyte solution is what determines the overall performance of the batteries. The electrolyte solution is made of salts and solvents, salts carry the charge and solvent provides the medium for the charge to travel from positive to negative terminals. Additives are added in the solution to  enhance the performance of the battery and reduce the corrosion of cathode/anode materials. Electrolyte is responsible for change in temperature and thus every geography has a different solution of electrolyte in the battery to avoid exponential change in temperatures. Some of these solvents turn solid at low temperatures thus they are only used in batteries with high voltage. LiPF6 is the most common electrolyte found in lithium ion batteries. 

Separator films are placed between the anode and cathode to avoid direct contact with each other. Films act as a connecting agent between two or more electrode species while slowly adhering them to the electricity based collectors. The electron passes through the pores of separator film without colliding with one another and smooth flow of charge is maintained.

The lithium ion cell works on the basic principle of chemical reaction getting converted to electrical energy. The graphite reacts with lithium cathode in the presence of electrolyte solution to generate charge in electrons. These electrons then travel from positive terminal to negative terminal without colliding with each other through the separator films resulting in power generation. 

The Indian chemical industry has large size opportunities in developing the battery components like cathode/anode, electrolyte solutions and separator films. 

Neogen chemicals have been extensively working on the lithium chemistry and has set up 2400MT capacity to manufacture lithium salts and derivatives. This facility will help in backward integrating the raw material requirements for electrolyte manufacturing. The company is further undergoing a capex of 35 Cr for manufacturing 250 MT of battery electrolyte at Vadodara facility. Advanced chemistry cell initiatives by the Government of India will enable the companies to use the PLI scheme offered by the authorities. The demand for lithium salts is expected to reach 70,000 MT by 2030 according to company estimates.

Tatva Chintan pharmachem limited is one of the manufacturers of electrolyte salts which are used in supercapacitor Super-Capacitors or ultra-capacitors are energy storage devices that store electrical energy via electrochemical and electrostatic processes. These capacitors are used in electrical grids and electric vehicles alongside the battery to give out a large amount of current in a short span of time, for eg: Starting an electric car requires high power discharge at stationary position, this charge is given by a supercapacitor. The electrolyte segment was negligible in the previous quarter but in Q3FY22, the contribution has gone up.

Gujarat Fluorochemicals are a manufacturer of PVDF films which are used as separator films and cathode binders in battery chemistry. The company is still under trials and has sent the samples for quality check from battery manufacturers. The company is undergoing a capex of 100 Cr for PVDF films. GFL is also in process of setting up India’s first PVDF solar film project which will be commissioned in the next financial year. The company is also setting up an integrated battery chemical complex to have a phased program on development of LiPF6 electrolyte and other lithium chlorides for battery chemistry. The company is evaluating opportunities of solar films and other renewable energy.

Polyplex Films manufacture PET films which are used along with separators resulting in composite PET/PVDF films. This combination results in high di-electric constant, High electrochemical stability and high tensile strength.

Tata Chemicals is having the battery recycling unit to source the metal salts required in the battery chemistry. The company is further leveraging in the battery chemistry space by signing a MoU for cell manufacturing. Company is planning to develop state of the art technology for manufacturers of cathode materials and the recovery and purification of cathode and anode active ingredients and developing a platform for electrochemistry solutions.  The company is also under development of the sodium ion battery technology. The abundance of sodium makes them a good alternative for lithium, however it does not possess the similar properties. Sodium ion batteries could not retain charge as much as lithium ion and take longer duration to charge which makes them inconvenient for commercial use. Technological development is under process to derive the appropriate cell chemistry in sodium ion batteries.