Ally Winning, European Editor, PSD
When modern EVs were introduced, the main reason for their initial slow sales was the range. However, battery technology has progressed and now some of the latest vehicles can get almost 600 miles on a full charge. As always in engineering, when one problem is solved another crops up, or in the case of electric vehicles, three more and they all concern the batteries.
The lithium-ion batteries we use at the moment are expensive, they take too much time to charge and they can be dangerous. The majority of these batteries are manufactured using nickel, cobalt, manganese (MCM) or nickel, cobalt, aluminium (MCA). These chemistries were chosen as they are the most energy dense, and therefore give the vehicle the greatest range. The downside is that those batteries are expensive – for example, a full battery pack replacement for a Tesla Model S is reckoned to cost around $15,000. The battery pack is the single most expensive item in the vehicle, and bringing that cost down would take the vehicles into far more consumer budgets. Much of the nickel used in those batteries comes from Russia, and the price of the metal has risen considerably since the war in Ukraine started. The price of cobalt has also doubled in the last 18 months, meaning that MCM/MCA batteries are likely to get even more expensive.
MCM/MCA chemistry lithium-ion batteries also have a tenancy to burst into flames. Spontaneous combustion or combustion from mishandling is infrequent, but it happens often enough to be a big concern for the potential purchasers of electric vehicles. And when it does happen, the fires are often difficult to extinguish.
However, there are other types of lithium-ion batteries that are not so dangerous, but they don’t offer the same energy density. Lithium iron phosphate (LFP) is the one technology possibly offers the greatest potential to be practical. It has a significantly lower cost because it is manufactured from common materials, without nickel or cobalt. LFP batteries have already been used in electric vehicles, initially in the far east, and aimed at the cheapest section of the market. Now Tesla has announced that it would adopt it for all of its standard range vehicles and this year, over half the Tesla vehicles built so far are powered by LFP batteries. In making the change, Tesla has cut costs, and also made its cars safer, as the thermal runaway temperatures of LFP chemistry are higher that other lithium-ion chemistries, meaning that it is much more difficult for them to reach the point of combustion. So LFP batteries are both safer and cheaper. The downside is that LFP batteries tend not to have the same range as other chemistries.
But things may be changing, and LFP batteries may be able to come close to reaching the levels of energy density of MCM/MCA batteries. Advanced Cell Engineering (ACE) has recently filed a patent application for its very large format (VLF) cell. The patent is for the company’s cell design and chemistry for a 1-meter cell-to-pack prismatic cell. The 1-meter long cells would be stacked in the vehicles battery pack directly. Currently, the most popular way of filling the battery pack is stacking scores of cylindrical 18650 format cells into modules, and those modules are used to fill the battery pack. Between 80 and 100 of ACE’s 1-meter prismatic cells would be installed directly into the battery pack.
ACE has also worked to improve the LFP battery chemistry, predominantly the anode and cathode. When the VLF cell is coupled with the advanced LFP chemistry it will offer significantly higher energy density than existing LFP offerings on the market today. "Today's LFP technology has an energy density of about 160 Wh/kg, while our patented Advanced LFP chemistry has an energy density of up to 200 Wh/kg. The unique architecture of a new 1-meter VLF cell will increase energy density even further - to around 250 Wh/kg," said Tim Poor, president of Advanced Cell Engineering.
The new VLF battery cell will reduce the size, weight, and complexity of an EV's battery system. ACE expects the cell design to be available for licensing in early 2023. “We are not a cell manufacturer and we're not going to be a cell manufacturer. So we will develop the technology and then license it to companies that are already making cells or to the automotive OEM,” concludes Poor.