Table of Contents
- 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”.
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.
Charge Process: Positive electrode (cathode) is oxidized (loses electrons) and Li+ ions pass across the electrolyte and are intercalated (insert between layers) in negative electrode (anode – graphite).
Discharge Process (opposite of charge process): An oxidation reaction occurs at the anode (-ve), Li+ ions are de-intercalated and migrate across the electrolyte to be re-intercalated into the cathode material.
- 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.
- 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
Iron ion battery by IIT
Lithium salt (Lithium hexafluorophosphate)
Inverters, automobile batteries, solar batteries
Mobile, laptop, electric vehicle batteries
Energy Density (Wh/kg)
30 to 40
Weight and Space
Heavy and occupies more space
Comparatively lighter and occupies less space
Low (2-4 years)
High (6-8 years)
Low (full discharge damages battery)
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.
World’s Lithium Reserves in Million Tons
World’s Lithium Production in Thousand Tons
- 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.
Reserves in MT
Region with reserves
Kendujhar and Jajpur districts
Presently, there is no production of cobalt from cobalt resources.
- 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%).
World’s Reserves of Cobalt Content (in TT)
World’s Production of Cobalt Content in 2017 (in TT)
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
Internal Combustion Engine Vehicles (ICEV)
Electric Vehicles (EV)
IC engine, Transmission System.
DC/AC motor, digital controller, battery pack.
Heavy due to large and heavy metallic engines with complicated design.
Motor engines are relatively lighter as they have fewer components and simplistic design.
Space occupied by components
Comparatively more because of large engines.
Comparatively less ==> more space for seating ==> good for congested countries like India
Less efficient because of loss of energy in the form of heat in IC engines and due to friction between transmission systems (rotatory motion has to be transmitted using a complex set of bearings and shafts).
More efficient as the loss of energy in the form of heat is very low (not many moving parts in motors) and transmission losses are minimum (the motor engine shaft transmits rotatory motion either directly to the wheels or with the help of fewer bearings and shafts).
More maintenance (frequent, oil change, components replacement) is required as there are many moving parts.
Less maintenance as the battery is the only major component to be replaced. (low recurring cost)
The initial cost of development and ownership
Comparatively low as the technology is in place for a century now.
High as the technology is still evolving.
Total lifecycle economic cost
Low (electricity cost associated with operating an EV over a distance of 1 km is significantly lower than the petrol/diesel cost required to operate a comparable IC vehicle)
Acceleration and speed control
Comparatively less as there many states like ignition, four stages of IC engine, transmission, etc.
EVs are much faster as the transmission of power and rotatory motion are almost instantaneous.
Comparatively low (EV are more efficient)
Once the tank is full ICEVs can travel non-stop for hundreds of km
The range of EVs at present is only a few hundred km.
Done in a few minutes.
Charging batteries take a few hours
Filling stations and other infrastructure is in place.
Charging stations are slowly popping up.
Resale value is falling as EVs are the future
Heavy dependence on imported fuels.
Clean electricity can replace fossil fuels.
India now generates 22% (79 GW) of its electricity from renewable sources alone.
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.
- 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.