BATTERY TECHNOLOGY RACE
It is the common word you come across when you talk to an EV user or if you have one, you might have experienced it too. This is because battery technology has some distance to go and lack of proper charging infrastructure make availability of topup scarce. Well then, what technology are we using now and what might be the case in future let’s have a look.
Lead-acid batteries are the cheapest batteries that are used currently in EVs. Most of the electric scooters and rickshaws use these batteries as they are commonly available and make the EV affordable. Lead acid batteries make up 25%-50% of the total mass of the vehicle in which they can store 30-50wh/kg of power. However the weight is compensated by not using a mechanical power train for the motor.
Nickel metal hydride batteries
Nickel metal hydride batteries are now considered as a mature technology and are fully commercialized. They are less efficient compared to lead-acid batteries at the same time they have a specific energy of 30-80wh/kg which is higher than lead-acid batteries. Nickel metal hydride batteries are known for their long life as seen in some Hybrid electric vehicles and first-Generation NiMH Toyota RAV4 EVs which are still operational even after 100,000 miles.
Li-ion batteries are the current buzz in the EV industry due to their high specific energy of 100-265wh/kg and low self discharge. The chemistry of a traditional li-ion battery is lithium cobalt-oxide cathode and graphite as anode. The use of highly volatile electrolyte and oxidized metal oxides makes them pose a risk of fire safety when they are punctured and charged improperly.
There are some changes made to the li-ion chemistry sacrificing specific energy and specific power to make it fire resistant, environment friendly and to have longer life spans. One among them is a li-Ferro phosphate battery with a specific energy of 90-160wh/kg which isfire resistant and has a lifespan of over 10years. Similarly, sand-based lithium batteries are under research and development and expected to have improved performance and three times more life span compared to traditional batteries.
Supercapacitors or Ultracapacitors
Supercapacitors or Ultracapacitors are capacitors with very high capacitance and they can be charged in seconds, Well this technology makes recharging just like refueling conventional petrol or diesel car. Unfortunately, they can only be used for short term energy storage as they also discharge faster than batteries. Supercapacitors are mainly used for storing the energy from regenerative braking in EVs.
Solid batteries have solid electrolyte instead of liquid or polymer gel electrolytes found in traditional li-ion batteries. As a result they can operate at supercapacitor levels which means they can be charged and discharged in minutes. As the electrolytes are solid they are more stable and safer than current batteries. The solid electrolytes still have a lot of research and development to be made to make it more durable and reduce material cost.
Aluminium-air batteries have air cathode; they produce electricity by the reaction between aluminum and oxygen from the air. These batteries have a greater specific energy density of 200wh/kg compared to lithium batteries. An electric vehicle with an aluminium battery can have eight times more range compared to lithium battery vehicles due to its lightweight construction. They are mainly used in defence and military applications because of the high anode cost which has to be replaced to recharge.
Graphene batteries have the potential to be the next big thing in the EV industry. A company called graphenano has come up with grabat batteries. These are graphene-based batteries that can be charged in just a few minutes and have a very high discharge rate compared to lithium batteries. They have aspecific energy of 1000wh/kg which is a lot compared to lithium and other batteries. Unfortunately, it comes with a cost.
It’s clear that battery technology has come a long way from the initial days. Battery technology is being improved to reduce cost, increase energy density, fast charging and safety. Looking at the development speed, the day to put a full stop for range anxiety and other major issues in EV’s are not so far.
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Photo by Mika Baumeister on unsplash
By Development channel.org
Ashley Pomeroy- Own work, CC BY-SA, Link
Yo-Co-Man-Own work, CC BY-SA, Link
Luca Bertoli-Own work, CC BY-SA, Link