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14 aoû 18

Race for the perfect EV battery

Vehicle manufacturers are involved in a headlong race to develop the next generation of batteries for electric vehicles.

Their urgency stems from their quest for a competitive advantage. The performance of current batteries is too similar for OEMs to stand out significantly in terms of either range or recharging time.

But new battery technologies hold out the prospect of dramatically increased range, the holy grail of zero-emission travel, as well as quicker recharges. The result is a series of new partnerships and alliances between manufacturers and third parties, raising the prospect of new players, such as vacuum specialist Dyson, entering the OEM arena, by capitalising on their battery expertise from other industries to challenge established automotive players.

Eventually the playing field will level again as all manufacturers gravitate towards the winning technology, but over the next few years there is the prospect of battery performance being a clear differentiator between vehicles. This will enable the OEMs that are first to bring game-changing batteries to market to build brand reputations that might last well beyond the point where they have lost their technological lead.

The perfect battery

Electric vehicle engineers face unavoidable compromises when designing batteries, forced to choose between a high power performance, a high energy storage capability, a low weight, a small volume, a long lifetime and a low price.

A step-change in price is likely to follow on from the economies of scale arising from greater demand for battery-powered vehicles, although some analysts warn that limited supplies of cobalt (the unstable Democratic Reupublic of Congo holds 60% of the world’s resources) required for lithium-ion batteries may drive up prices. At the beginning of 2017, one tonne of cobalt cost €28,000 ($32,500), but the price had risen to €60,000 ($69,750) by July 2018.

Current batteries

In current model ranges from the major electric vehicle manufacturers, almost all vehicles rely on versions of either nickel-metal hydride or lithium-ion batteries to store charge and power a motor when required. Nickel-metal hydride holds the advantage at lower temperatures, where battery performance can otherwise suffer, and is typically more common in hybrid vehicles (used by the likes of Toyota and Lexus). However, experts consider them to be an interim solution, due to their heavier weight, lower energy density (the amount of energy that can be stored per unit of weight or volume), and lower deep-cycling capability than lithium-ion batteries. Nickel-metal hydride has survived this far largely because it is a significantly cheaper option than lithium-ion.

In every other respect, however, lithium-ion has the upper hand, which is why it is almost universally the battery of choice in pure electric vehicles.

Batteries of tomorrow

Looking to the future, though, OEMs are investigating and investing heavily in so-called solid-state batteries. These replace the liquid or gel-form electrolyte in a lithium-ion battery with a solid, conductive material. The result is a battery with higher energy density, better safety and enhanced fast-charging capabilities. They could also potentially occupy less than half the size of lithium-ion batteries.

Earlier this year Volkswagen signed a joint venture with California-based QuantumScape to develop solid-state battery technology, which it said could extend the range of the e-Golf to 750km, compared to the car’s 300km with its current lithium-ion batteries.

Dr Axel Heinrich, head of VW Group Research, said: “The solid-state battery will mark a turning point for e-mobility.”

BMW, meanwhile, has formed a partnership with Solid Power, a developer of solid-state battery technology, while Toyota is collaborating with external research organisations as it starts research on next-generation batteries whose energy density greatly exceeds that of the lithium-ion batteries currently used for electric-powered vehicles.

Solid-state battery

At the moment, the front runner to be the next generation of battery, the so-called solid-state battery, faces two barriers; firstly, the development of the technology; and secondly, the ability to manufacture at commercially viable prices. More on this later.

As for the next step beyond… at the Detroit Motor Show, Samsung SDI exhibited graphene balls battery technology, which it claimed will enable a a 45% increase in capacity and five times faster charging speeds than standard lithium-ion batteries.

Graphene is 100 times more effective than copper in conducting electricity and displays remarkable electron mobility – 140 times faster than silicon – which makes it an ideal material for fast charge.

Authored by: Jonathan Manning