The heart of e-mobility

There are numerous factors that effect the efficiency of an electric vehicle, but none is more important that the efficiency of its battery, according to Prof Dr Maximilian Fichtner, a chemist engaged in battery technology research.

As Managing Director of the Helmholtz Institute Ulm Electrochemical Energy Storage (HIU), his focus is on the research and development of electrochemical battery concepts for the next generation and beyond, the institute employing 150 scientists to research and further develop the fundamentals of future-proof energy storage systems for both stationary and mobile use. Imminently qualified on the subject of energy storage, Fichtner is not only Director of HIU, but also group leader of the Solid State Chemistry research group. In addition, he is also the Director of CELEST, Centre for Electrochemical Energy Storage Ulm & Karlsruhe, a research platform that combines application-oriented basic research with practical development and innovative production technologies. He is also the spokesperson for the POLiS Excellence Cluster, which conducts battery research on batteries of the future that are more powerful, more reliable, more sustainable and more environmentally friendly than current lithium-ion batteries.

Of course when it comes to batteries, size is one of the important factors – specifically maximising storage in the smallest possible battery.

“Some manufacturers are working with the so-called ‘cell-to-pack design’, or ‘cell-to-body design’, [which means] battery packs are no longer made up of chocolate bar-sized cells but are instead plank-sized. Such larger units require less packaging material, thus providing more space for the actual storage material. They achieve an integration density of more than 70 percent, while normal batteries only achieve about 50 percent,” says Professor Fichtner.

“EV manufacturers aiming to develop their own batteries can take these technological leaps into account right from the outset. After all, it’s not about the individual battery cell, but rather about building cells that are as space-saving and yet as large as possible.”

But while maximum battery capacity is important, just as important is its charging power says Professor Fichtner.

“It's important for large batteries to be able to recharge quickly,” he says. “At the end of the day, that is what it really is all about. When you can charge your EV battery from 10 to 80 percent in just 10 minutes, it’s game over for the combustion engine.”

“There are materials that allow batteries to be charged more quickly, while others will take longer. Technically speaking, lithium ions move from the cathode to the anode when charging, and the anode stores lithium ions when the battery is charged.

“Currently, a graphite layer is added to the anode. There are battery manufacturers who want to use silicon-carbon composites instead, as they can be charged much faster, even at low temperatures. There is a lot of development potential as far as materials are concerned. By changing the material of the anode alone, the cell as a whole will gain 30 percent more storage capacity. So there are still incredible breakthroughs ahead of us.

“But apart from that, if you want to charge a 60-kWh battery in 10 minutes, you will need an EV charger with a charging power of 360 kW. So right now, it’s not the battery power that is limited, but rather the EV charging infrastructure.”

Longevity too is a factor and something potential EV owner often question when looking to purchase an electric vehicle, but battery degradation the we see in the likes of mobile phone batteries is not something that afflicts EVS according to Dr Fichtner.

“Such batteries are very different, and smartphones are actually designed to be replaced after three years. In an electric vehicle, the battery control system is much more intelligent, and the battery is protected from overheating and other harmful influences in many ways, such as intelligent charge management.”

“Studies with newer vehicles show that after five years, 95 percent of the battery's residual capacity is usually still available. The traction battery in an electric vehicle is designed to complete 2000 full cycles. For example, 2000 times a range of 500 kilometres makes a million kilometres of capacity.”

Once a battery ceases to be efficient enough for use in an EV, it still has many years of viable work ahead of it as a stationary storage unit according to Dr Fichtner. Ultimately though, its core ingredients will be recycled and reused, with around half of the raw materials needed for battery production coming from recycling by 2034.

This will be important for future battery production and also to keep costs to a minimum, given that batteries account for a large part of the cost of an electric vehicle. In order to bring that cost down in the future, Professor Fichtner says it will be necessary to use less expensive materials – raw materials that are common, occur worldwide, and can be mined uncritically. In addition, manufacturers must develop new energy- and time-saving processes.

Apart from the shift to more sustainable materials, cost reduction he says is the megatrend in battery production. 

“This applies everywhere – less space, less energy, less time. There's a lot going on in development, and it's happening faster than you may sometimes think. Battery development is incredibly exciting right now.”