EuroWire November 2018

Transatlantic cable

Results from a college lab hold promise for freeing lithium-ion batteries from the trade-off between fast charging and long life The fast charging of cold lithium-ion batteries (LiBs) entails the risk of lithium plating. When metallic lithium is formed in a battery, it can severely reduce the battery’s lifespan and increase its instability. Now, researchers at Penn State University believe they have found a way to achieve both 15-minute charging and a 12-year battery lifespan in temperatures as low as -50ºC. As reported in ChargedEVs , the Penn State team used a self-heating LiB structure with embedded nickel foils that rapidly heat the cells before charging. The foils also function as an internal temperature sensor while adding only 0.5 per cent in weight and 0.04 per cent in cost. Improving one property without sacrificing another is, according to the study’s author Xiao-Guang Yang, “always nontrivial.” For example, electrolyte with superior performance at low temperatures is quite often unstable at high temperatures. It is extremely difficult – if even possible – to develop materials with a high rate for charging while preserving durability and safety over a wide range of temperatures. The research team apparently met with success in its effort to free battery science from such trade-offs. Specifically, Prof Xiao-Guang told ChargedEVs : “[We] present a cell structure that can be actively controlled to achieve lithium plating-free (LPF) fast charging in any ambient temperatures.” (“Penn State Researchers Develop Cold-Weather Fast Charging Method for Li-ion batteries,” 22 nd August) † † LiBs have always presented what ChargedEVs calls “a complex Goldilocks problem” – either too cold or too hot. If the Penn State research proves out, it could mean an end to the long recharge times of today’s EVs at low temperatures. † † Noting that Germany’s Mercedes-Benz and other high-end brands are pushing aggressively into electric cars in a challenge to Tesla Inc of the USA, Bloomberg News on 4 th September reported that Mercedes has fired a shot across Tesla’s bows. The world’s largest maker of luxury cars said it is rolling out the first in its projected series of battery-powered models, leading a growing array of elite brands targeting the California-based market leader. Parent company Daimler’s plan to develop its EQ electric line calls for the Mercedes EQC crossover to start production in the first half of 2019. Daimler, which intended to invest $12 billion in its electric-vehicle push, has ended up spending more, the company’s CEO Dieter Zetsche told reporters in Stockholm at the model’s world premiere. “There is no alternative to betting on electric cars, and we’re going all in,” said Dr Zetsche. “It is starting right now.” According to Bloomberg , the EQC will be assembled at the Mercedes factory in Bremen, where the automaker also makes its best-selling C-Class sedan. Daimler will build the car in China for the local market. Elsewhere in automotive . . .

He added that the automaker did not see “significant risk” for its other two imports to North America: the EcoSport crossover from India and the Transit Connect van from Spain. The Focus Active is sold in Europe, and Ford said it would continue with plans to build it in China for that market. † † Automotive News reported that General Motors asked for an exemption from the tariff on its China-made Buick Envision, an application which is currently under review by the Commerce Department. Executives have warned that, if it does not receive that exemption, GM could drop that vehicle from its US line-up. Ford said an exemption would not have applied to the Focus Active because of its production timing and thus did not seek one. Having made its name for cyclonic separation technology in vacuum cleaners, Britain’s Dyson turns its attention to EVs Reuters reported on 30 th August that, in another step by Dyson to show that it is serious about building an electric car, the British vacuum-cleaner maker has announced that it will build a vehicle test track at a former World War II airfield in Wiltshire, England. Plans announced previously called for an office building to accommodate 2,000 employees to work on the company’s electric vehicle (EV) project. Three EVs are to be produced. The first, a “proof-of-concept” model – to iron out the production processes and establish the brand – is scheduled to roll out in 2020. James Dyson, the inventor of the ball vacuum cleaner and founder of the company, told the Financial Times in a March interview that the first model will be made only “in the low, single-digit thousands.” According to Eric C Evarts of Green Car Reports , Dyson is developing solid-state lithium batteries for its cars. Since these batteries may not be ready in time, the prototype car may instead make do with conventional lithium-ion (li-ion) batteries with liquid electrolyte. (“Dyson Plans to Build Electric-Car Test Track in Britain,” 31 st August) Mr Evarts noted that Dyson bought, then sold, Sakti3, a Michigan-based start-up set up to develop solid-state batteries, and has kept most of its patents. Dyson has said it plans to use these solid-state batteries in later models of its new EVs. James Dyson has suggested that Dyson cars will look “quite different” from other vehicles, and this may be so. The company is known to have developed expertise in lightweight materials, which could allow flexibility to produce different car-body designs. Green Car Reports cited the example of the BMW i3, with its carbon-fibre reinforced plastic panels, † † Mr Evarts observed that several other companies are also working on developing various solid-state lithium battery technologies, which could lead to lighter-weight, cheaper and safer batteries for electric cars. However, mainstream automakers such as Volkswagen do not expect to have such batteries on the market until at least 2025.

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November 2018