Porsche provides overview of EV battery state of play

Battery performance is still a limiting factor to the widespread adoption of EVs by the buying public, with range anxiety rightly or wrongly an issue. This applies whether one is building an EV Super Mini or a sportscar such as the Porsche Taycan. The manufacturer of the latter has recently released a summary of its view of the current battery market, drawing on input from both its engineers and experts from third party institutions.

According to Porsche, the reality is that currently, batteries are still a compromise. “For Porsche in particular, high charging performance plays a major role,” says Dr Stefanie Edelberg, engineer at Porsche Engineering. “Sporty driving drains the battery faster, and the customer doesn’t want to have to wait an hour to fully recharge it.”

Unfortunately, as Dirk Uwe Sauer, professor of Electrochemical Energy Conversion and Storage System Technology at RWTH Aachen University, notes, “Battery technology for cars works well in practice, including in terms of performance, charging and service life. However, several extreme properties cannot be combined. You can’t have everything at once.” Ultra-fast charging combined with a high energy density? That’s not possible because the service life would suffer from this combination.

Sauer is therefore skeptical about media reports regarding supposed miracle batteries, because usually a single parameter is optimized at the expense of others. “There will be no universal all-rounder battery,” he says.

Though other high-energy density, energy storage systems for electric vehicles are under development, lithium-ion cells will remain the technology of choice for the foreseeable future. They have acceptable energy and power density, while also boasting good robustness, which enables them to withstand around 2,000 charging cycles in an all-electric vehicle, at a high depth of discharge, before losing their utility. A figure which could be further improved upon in the future. The consensus at both Porsche and other OEMs being that lithium-ion technology still offers a wealth of development opportunities in terms of cell chemistry and cell design.

For example, according to researchers at the Fraunhofer Institute for Systems and Innovation Research (ISI), energy density has almost doubled over the past 10 years in large-format lithium-ion battery cells for electric cars – to an average specific energy of 250Wh/kg (or 500Wh/l energy density). By 2030, Porsche predicts energy density could increase by a factor of two while other properties of lithium-ion cells can also be improved...

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Article originally published on Engine + Powertrain Technology International.