Lithium-ion battery, Internal Combustion Engine vs. Electric Vehicles

• IIT Madras researchers have fabricated a rechargeable iron ion battery.
• With the increased focus on electric vehicles, it is essential to develop rechargeable batteries that are cheaper.
• With no lithium reserves in India, the stress is on developing rechargeable batteries of comparable performance using materials other than lithium.
• John B Goodenough, M Stanley Whittingham from the US and Akira Yoshino from Japan won the Nobel Prize in Chemistry 2019 “for the development of rechargeable lithium-ion batteries”.

Lithium-ion battery

Schematic of a rechargeable battery (Image Credits)

• Anode, cathode, electrolyte and separator are the main components of a lithium-ion (rechargeable) battery.
• The two electrodes are immersed in the electrolyte and are separated by the separator.
• The anode is usually made up of graphite (carbon).
• Carbon graphite has a layered structure that can store the lithium ions in between its layers.
• The cathode is made up of a combination of lithium-cobalt.
• Lithium is unstable in the element form; hence the combination lithium-cobalt oxide is used for the cathode.
• Cathode plays an important role in determining the energy density of a Li-ion battery.
• The higher amount of lithium, bigger the capacity.

Working of a typical lithium-ion battery

• Both electrodes in a li-ion battery can intercalate or ‘absorb’ lithium ions.
• When the battery is being charged, lithium ions are absorbed (stored) in the anode.
• During discharge, lithium ions naturally flow back to the cathode through the electrolyte.
• This creates free electrons in the anode which move along the wire generating electricity.
• The process (to and fro movement of lithium-ion) repeats with each charge and discharge cycles.
• Electrolyte (lithium salt) enables the movement of lithium ions between the electrodes.

• The separator functions as a physical barrier keeping cathode and anode apart.
• It prevents the direct flow of electrons and lets only the ions pass through.
• While the cathode determines the performance of a battery, electrolyte and separator determine its safety.
• Permeable polymer membranes such as polyethylene (PE) and polypropylene (PP) are used as separators.

Why lithium?

• Lithium is the lightest metal and a powerful reducing agent (willing to donate its electrons).
• Lithium-ion batteries capitalize on the strong reducing potential of lithium ions to power the redox reaction — reduction at the cathode, oxidation at the anode.

Iron ion battery developed by IIT Madras

• Fe2+ ions are the charge carriers in iron ion battery (in lithium-ion battery lithium ions do the job).
• The iron ion battery uses mild steel as the anode and Vanadium pentoxide as the cathode.
• The large inter-layer spacing in vanadium pentoxide makes intercalation easier (loss and gain of ions).
• In pure iron, intercalation is not possible. But, a small amount of carbon in mild steel facilitates this process.
• Ether-based electrolyte containing dissolved iron perchlorate is used as an electrolyte.
• The energy density of iron ion battery is 220 Wh/kg (350 Wh/kg in case of lithium-ion battery).
• When compared with lithium metal-based batteries, iron ion batteries would be cheaper yet safer.

Energy density is measured in watt-hours per kilogram (Wh/kg) and is the amount of energy the battery can store with respect to its mass.

How is iron better than lithium?

• The redox potential (potential to lose or gain electrons) of iron ion is higher than lithium-ion.
• The radius of the Fe2+ ion is nearly the same as that of the lithium-ion.
• Iron is more stable during the charging process and therefore prevents short-circuiting of the batteries.
• When more iron ions bind to the cathode, more energy (higher energy density) can be stored in the battery.

Comparison: Lead-acid battery, Lithium-ion battery & Iron ion battery by IIT

Lithium

Among twelve minerals identified as strategic minerals, Lithium and Cobalt are significant.

• Lithium is lightest known metal. It has a density of 0.534 g/cm³ (half as dense as water).
• It’s light and soft and has the lowest melting points of all metals and a high boiling point.
• Lithium-ion batteries are key to lightweight, rechargeable power for laptops, phones, electric vehicles.
• Lithium and another battery component, cobalt, could become scarce as demand increases.
• China controls most of the lithium supply across the world.

Cobalt

• Cobalt is an important ferromagnetic alloying metal having irreplaceable industrial applications.
• Cobalt is extracted as a by-product of copper, nickel, zinc or precious metals.
• Superalloys made of cobalt are wear & corrosion-resistant at elevated temperatures.

Role of cobalt in Lithium-ion batteries

• Lithium-cobalt-oxide is used as the cathode in rechargeable batteries.
• Lithium-cobalt-oxide is an intercalation compound with the lithium, cobalt and oxygen arranged in layers.
• Cobalt is indispensable to assure the rate performance (rate of charging & discharging occurs).
• When the lithium-ion arrives or departs from the cathode, cobalt changes its oxidation state (compensates for the gain/loss of charge) so that the lithium-cobalt-oxide stays electrically neutral.
• Cathodes are commonly oxides made from transition metals such as nickel, cobalt, copper, iron, etc.
• Replacing the costly cobalt with significantly cheaper nickel can be a fire hazard.
• Aluminium & manganese can be added to stabilize, but it lowers the capacity of the cell by a small amount.

Distribution of Cobalt Reserves across India and the World

• The demand for cobalt is usually met through imports.
• Recycling technologies for recovery of cobalt from waste Li-ion batteries have been an evolving process.
• Imports of cobalt and alloys were at 875 tonnes in 2017-18.
• Imports were mainly from USA & Canada (13% each), Belgium (12%), Norway & UK (9% each) and China (8%) & Morocco (7%).

Internal Combustion Engine Vehicles vs. Electric Vehicles

Mains Practise: “The Internal Combustion Engine Is A Dead Man walking.” Critically analyse this statement.

Mains Practise: “The age of the Internal Combustion Engine (ICE) is over. Electric cars are the future.” Critically analyse this statement.

EVs are a lot better than ICEVs

Demand for EVs is rising rapidly

Electric car battery life is increasing

• One major factor that turned into a bottleneck in adopting EVs is battery life.
• At present lithium-ion batteries in EVs have a lifecycle of 6-8 years which is decent.
• With improving technologies, this is only set to go up.

Battery capacity is increasing, and prices are falling

• Lithium-Ion batteries are increasing in energy density at a rate of 5-8% per annum.
• Battery Costs are falling: The main cost of an electric vehicle is the cost of the battery. Lithium-Ion batteries cost $1,000 per kWh in 2010. By 2017 that cost had fallen to $200 per kWh, and it won’t stop there.

Favourable policy

• China and India are aggressively pushing for electric mobility with a slew of measures.
• India reduced GST on EVs from 12% to 5%. Introduced schemes like FAME, FAME II.