ENERGY
Fund for battery research
The UK’s Industrial Strategy Challenge Fund (ISCF) to stimulate battery research was launched in summer 2017. The research element will be coordinated by the Engineering and Physical Sciences Research Council, which will oversee the setup of the Faraday Institution, a virtual research institute with a small HQ to support fundamental science. The translation of fundamental
science to industry is to be handled by the government’s innovation agency, Innovate UK, and will include matched investment by industry. The industry scale-up is being assigned to the Automotive Propulsion Centre, which will create an open access facility with technology scale-up capabilities. In July 2017, the fund invited
proposals in four areas: battery degradation; the all-solid battery with lithium and sodium metal anodes; multi-scale modeling; and circular economy/recycling. More funding is to follow and will be administered by the Research Institute for the lifetime of this ISCF Faraday Challenge. The first four ‘fast start’ research
projects will receive up to £28m and projects will run for up to three years. This can help the UK build on strengths in battery research and in business too. In recent months, FTSE 100 chemicals group Johnson Matthey announced plans to invest £200m in batteries for electric vehicles. It first entered the lithium ion battery market in 2012 and has since spent >£100m on acquiring new battery technologies. Currently, South Korea and
Japan are leading the way in terms of battery technology. Building an ecosystem of battery-focused companies and innovative research groups should give UK industry a helpful push. ‘We want to create a culture where potentially a [company like] LG Chem might invest inwards in the UK,’ says Wu. ‘At the end of the day, we want to create economic value for the UK.’
consumer electronics and most experts believe they will likely power electric vehicles for the next decade. Costs have fallen dramatically, from around $1000 per kilowatt-hour of storage capacity in 2010 to around $200 today. However, ‘cost is still a challenge,’ says Billy Wu, a battery researcher at Imperial College London, UK. ‘People often quote a target number as roughly $100/kWh.’ Battery gains are a slow,
steady creep forward, Wu notes. Experts predict that incremental improvements will lodge annual gains in energy density of between 5 and 8%. Car-maker Tesla recently began improving the energy density of its Li ion batteries, by doping the graphite anode with around 5% silicon. The viability of silicon as an anode material for Li ion batteries was first reported in 1999, illustrating the time gap between basic research and commercial applications. Consumer goods tend to run on cathodes of lithium cobalt oxide, which offers high energy density, while electric cars tend to run on cathodes of lithium nickel manganese cobalt oxide (LiNiMnCo2
,
or NMC) chemistries, preferred for their stability. The industry NMC standard is one-third cobalt, nickel and manganese apiece, 1-1-1, but is gradually upping the nickel content of the cathode to improve voltage and reduce expensive cobalt. Batteries with ratios of 60% nickel, 20% cobalt and 20% manganese have been launched commercially, cutting down on cobalt, which is about six times the price of nickel. ‘LG Chem announced it is going to release its 8-1-1 chemistry next year,’ says Wu, further reducing the cobalt levels. But it’s not all about materials.
Offer’s team at Imperial takes market-ready or prototype battery devices into their lab to model the physics and chemistry going on inside, and then figures out how to improve them. The big opportunity for technology disruption lies in extending battery lifetime, he believes. Lithium batteries are built from layers, each connected to a current connector and theoretically generating equivalent power, which flows out through the terminals. However, improvements in design of packs can lead to better performance and slower degradation. For many electric vehicles, cooling
plates are placed on each side of the battery cell, but the middle layers get hotter and fatigue faster. Offer’s group cooled the cell terminals instead, because they are connected to every layer. ‘You want the battery operating warmish, not too hot and not too cold,’ he says. ‘Keeping the temperature like that, we could get more energy out and extend the lifetime threefold.’ If the expensive Li ion batteries in electric cars can outlive the car, he says their resale value will go up and dramatically alter the economic calculation when purchasing the car. ‘If we can get costs down, we will see more electric vehicles, and reduced emissions and improved air quality,’ Offer says.
Alternatives to lithium ion Battery systems management and thermal regulation will allow current lithium batteries to be continually improved, but there are fundamental limits to this technology. ‘Lithium ion has a good ten years of improvements ahead,’ Offer predicts. ‘At that point we will hit a plateau and we are going to need technologies like lithium sulfur.’ Li sulfur has a theoretical energy
density five times higher than Li ion. In September 2017, US space agency NASA said it will work with Oxis Energy in Oxford, UK, to evaluate its Li sulfur cells for applications where weight is crucial, such as drones, high-altitude aircraft and planetary missions. However, Li sulfur is not the only
challenger to Li ion. Toyota is working to develop solid-state batteries, which use solids like ceramics as the electrolyte. ‘They are based around a class of material that can conduct ions at room temperature as a solid,’ Offer explains. ‘The advantage is that you can then use metallic lithium as the anode. This means there is less parasitic mass, increasing energy
24 10 | 2017
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