We are most concerned about batteries when our smartphone is about to shut down. But across the world, people have been anxiously waiting for high-energy packs to hit the market that can drive you around. More so, because little progress have been made since the 1930s in the field of battery-powered Electric Vehicles or EVs. This is important given the positive impact such a shift, from traditional fossil fuels to greener electric drive technology, can have on our critical environment thats degrading everyday. This is a revolution in waiting, but what stops us from making this shift are the two most challenging problems scientists have been facing all this while i.e. prices & charging time w.r.t battery capacity.
With the advent of Li-ion batteries, we could produce a lot of handheld gadgets like tablets, mobiles, cameras etc, but they haven't made a very big impact as far as EVs are concerned. The reason predominantly is the first challenge i.e. Pricing. Because Lithium is a rare metal & that too found mostly in South America(bringing politics into the scenario), add to that the complex purification processes that have to be followed, the costing has been very high @ $350 per kilowatt-hour average in the US market. For industry watchers, the holy grail for widespread EV revolution is the pricing of $100 per kilowatt-hour.
We will come back to pricing again but before that lets discuss our second problem a bit - Charging Time. Normally, our home inverter battery will take 7-8 hours to get fully charged (150Ah, Lead Acid type). Now, imagine waiting for that much time at a fuelling station for getting a full tank. Horrific to say the least. Let me tell you that a 150Ah battery if fully charged, can only take you 60 kms ahead. Thats it. While it takes just 5 mins for filling petrol/diesel & 10 minutes in case of CNG and they offer much higher travel range from 150 kms to more 600 kms. This problem however, has been half solved & I guess thats the farthest we can go right now. Most of the electric cars/bikes manufacturers offer 70-80% charging in 30-40 minutes. Thats a considerable improvement given the inherent nature of the charging process. Take for example, a bucket say 1 litre, in order to fill it we will open the tap & will let the water flow with full force, to fill it quickly. But, as the bucket becomes 80% full you will observe that the water starts spilling out due the high force of tap water, as a result you need to slow down as you reach the top limit. Same is true with Batteries, & you definitely don't want current spilling out of them. As of now, the development of quick charge batteries is at a very nascent stage with only Toyota doing the major work, it has tested a couple of prototype cathode chemistries of Lithium only but both these experimental compounds are unstable at room temperature. So we have miles to go in this regard.
I would still want to discuss two more issues of EVs i.e. speed & range, before we get back to Pricing part. Early electric cars were pretty slow & could cover only small distances on single full charge e.g. a golf cart. Improvements in high torque sustaining motors & batteries ofcourse, have taken care of both these issues to a large extent. The biggest name in EVs today is Tesla Motors run by the iconic tech entrepreneur Elon Musk, which produces by far the best performing all-electric cars namely Model-3, X & S, with a range of 300 kms to 500 kms & top-speed of more 150 km/hr. Hybrid EVs like Chevy Volt(best performing & my personal favorite), Toyota Prius & Nissan Leaf use a petrol generator coupled with an electric drive to sustain the charge of batteries for extended range over an electric car upto 600 kms & a combined mileage of around 40 kmpl, and 150 km/hr top speed. Its worth noting that these hybrids are lower priced than Tesla's electric only models. Its simply because to provide for this kind of speed & range, more powerful & hence bigger battery pack had to be used by Tesla. So that brings us back to our main concern that is Pricing of Li-ion batteries. Lets also spare a thought on why such advanced & expensive battery technologies were needed. The answer is for a laymen - weight & for a technical person - energy density. Lithium ion batteries are one-third in weight as compared to Lead-acid battery of same rating. This is crucial for cars/vehicles and Li-ion has effectively solved it. In addition to lighter weight, Li-ion batteries also have double life. That propels Li-ion as the foremost battery choice among automobile manufacturers.
Now, let us consider the fact that Indian Govt recently announced an Electric Bus scheme for public transport in major cities, cost of each of these buses is INR 3 Crores & the cost of this Bus without battery is INR 1 Crore. Now, Tesla founder Elon Musk with his another venture i.e. a gigawatt factory( annual production capacity of 1 GWh or 1000 MWh) in Nevada, California is planning to bring the prices below the $100 per KWh mark, often referred to as the "Holy Grail of Electric car revolution". This sort of production capacity is what the world possesses at the moment, combined. And guess what the production is deemed to start in early 2017. So, the revolution may be fast approaching. BUT hold on, despite the given fact that such a pricing will cut the Indian Govt's expenditure on these Electric buses by a staggering 50%, its still not the best offer yet. The best offer proposes to cut the prices by 40% over the so-called "$ 100 per KWh Holy grail"
This is to be achieved by the advent of Sodium-ion batteries which is also slated to hit the market in 2017 and the important thing is that the existing Li-ion battery manufacturing setup can be used for producing them too, with minor modifications. Let us understand a battery first :-
A battery consists of three main parts, an anode(positive terminal), a cathode(negative terminal) & an electrolytic solution that can help in ions exchange(flow of current). Anode is usually Graphite, Cathode is a Metal oxide and electrolyte is a salt of the same metal. While discharging(supplying power to load), the Metal-ion (Li or Na) moves from Cathode through the external circuit into Anode, a process known as intercalation. Now, the inherent problem with Sodium ion is that it is 25% bigger than the Lithium ion. This can very well undo the weight advantage gained with Li-ion batteries but the scientific community seems to have managed to keep the weight within targets. Faradion Energy 0f UK has been particularly upbeat about their new Na-ion battery chemistry which they plan to bring to the market. In an email response, Deanna Holmes, Technical Administrator said the weight of their Na-ion battery will be comparable to an Li-ion battery. The website of Faradion clearly claims that their prototype will have an energy density higher than that of Li-ion.
Sodium is the 6th most abundant element on the planet, and its salt costs less than 10% of the equivalent Li salt. This makes Sodium obvious choice of battery enthusiasts across the world. These batteries will be dirt cheap and will completely change the game. For a country like India, its impact is going to be both economical & ecological given our high import bill of crude oil. It will importantly reduce the dependency on Gulf states & usher in an era of energy self-reliance. This to me is the new & real "Holy Grail of EV revolution".
