Sodium batteries might speed up the shift to electric vehicles

A reliable and high-performing sodium battery has for decades been the greatest dream of the energy storage industry.  Lithium prices have skyrocketed to euro 12,000 per ton and might rise even higher in the future.  The production of lithium is energy-intensive and most lithium ores contain only tiny concentrations of the element.  If the world would have, in the future, one billion or possibly even three billion electric vehicles using lithium batteries, vast acreages should be mined and devastated to produce all the lithium required for them.  Such huge mining operations would produce significant amounts of heavy metal pollution and radioactive emissions (uranium and thorium and their decay products).

Sodium, on the other hand, is a waste matter that can be acquired with a negative cost.   For instance every desalination plant in the world making freshwater also produces large quantities of sodium chloride, every day.  Actually, the sodium chloride is a growing problem to the desalination plants, especially the ones situated on the shores of shallow seas or bays.  The activities of such desalination plants have already started to increase the salinity of the sea and hurt all kinds of sea creatures accustomed to normal levels of salt in the water.  Therefore, using the sodium for something – instead of just dumping all the brine back to the sea – would be beneficial for the environment.

Sodium batteries would be one obvious way of utilising this element in the sea salt.  However, for a long time nobody was able to make a sodium battery that could be re-charged more than 50 times.  It was, above all, very difficult to find suitable materials for the cathodes (for the negatively charged electrodes) of the batteries.

This inadequate durability has been the main obstacle on the way of sodium batteries, but it now seems that a Finnish company called Broadbit Batteries may have been able to solve the problem.  According to David Brown, the CEO of the company, Broadbit Batteries had already in October 2018 been able to re-charge its sodium battery 250 times.

According to Brown Broadbit Batteries is very like to reach the level of thousands of recharging cycles within a couple of years.   Even though the people in Broadbit Batteries seem to be confident that they can reach such a goal, it is of course impossible to say for sure whether this will happen or not.

However, Broadbit Batteries has already surpassed the old record in a rather significant way and may have made the decisive breakthrough.  After lithium batteries had reached 200 reloads, it did not take long before they were around 10,000 plus recharging cycles.   Besides, Broadbit Batteries announced, in April 2019, that it has developed a new way of producing cathodes.  The company has not given out any details, but the announcement concerning a new kind of cathode coming from a company developing sodium batteries sounds rather interesting, because it has been the cathodes which have been the most important bottle-neck on the way of developing sodium batteries that can be recharged thousands of times.

Even with 250 recharging cycles, sodium batteries should be able to compete with lithium for the electric vehicle market, for a number of different reasons.

The sodium batteries of Broadbit can already store 300 Wh per kilogram, while the typical figure of lithium batteries is 100 – 150 Wh per kilogram and the maximum achieved by the highest-performing mixtures of lithium and other substances has been around 250 Wh/kg.  The official goal of Broadbit is 400 Wh/kg, which they may or may not be able to achieve.  In any case Broadbit Batteries has already been able to reduce the recharging time of their experimental car batteries to 0.5 hours, which is a major achievement and a big improvement compared to the current lead or lithium batteries.

The price of lithium batteries is currently around USD 400 per kWh when small purchases are made but can go down to USD 250 per kWh in connection to very large, massive deals.  The goal of Tesla’s Gigafactories is to push the price down to USD 125 per kWh.  Broadbit Batteries has already achieved the price level of USD 70 per kWh.

These are very major benefits compared to current lithium batteries.  The prices are of course not directly comparable because best lithium batteries can already be recharged 10,000 – 20,000 times.  This means that in 2016 it cost about 7 eurocents to store one kilowatt-hour of electricity for example to Tesla’s  PowerWall batteries and the use it, during the life-span of the battery.  When a sodium battery costs USD 70 per kWh and the number of reloading cycles is 250, the cost of storing and using one kilowatt-hour of electricity is 24 eurocents, during the lifetime of the battery.

Even the level Broadbit Batteries has already reached might be enough to make a difference in the field of electric cars, but sodium batteries will not be useful in connection of solar power plants before the number of recharging cycles rises from the low hundreds to several thousands.  However, when we have sodium batteries that can be recharged thousands of times, the price of storing solar power will collapse.  

With sodium batteries there would also be a virtually unlimited scalability. In other words, the new technology might soon make the storing of extra solar and wind power into sodium batteries a genuinely economical option.