Robust demand for energy storage in electric vehicles, grid-tied installations, smart phones and laptop computers continues to fuel the fortunes of companies producing lithium ion, or Li-ion, batteries, and has sparked a boom in battery production capacity and lithium exploration. As a result, the Solactive Global Lithium Index, a composite of the world's largest publicly traded lithium miners and battery producers, was up roughly 57% over the past year, as of Dec. 15, and has more than doubled in the past two years.
Backed by BASF, ESS Inc. has big plans for its flow batteries.
Source: ESS Inc.
Nevertheless, many developers and investors focused on alternative battery technologies believe that, as the need for longer-lasting, faster-charging and safer approaches grows, Li-ion's days as the dominant battery chemistry are numbered. Among the most promising electrochemical insurgents are flow batteries, which store energy in external tanks, using either vanadium, zinc or iron as their active ingredient, and solid-state batteries that use a different material for the anode, such as lithium metal.
"We all know that lithium ion is the king right now," Susan Babinec, senior commercialization adviser at the U.S. Department of Energy's Advanced Research Projects Agency-Energy, or ARPA-E, said in a panel discussion Dec. 13 at an energy storage conference in San Francisco. "Lithium ion has been around for 30 years and is produced at a multi-GWh scale all around the world, and so its price is coming way down ... [but] it's approaching a plateau."
ARPA-E has invested roughly $250 million in energy storage research and development to date, a pittance compared to the around $25.6 billion pumped into energy storage worldwide between 2004 and the second quarter of 2017, according to Bloomberg New Energy Finance data. ARPA-E's niche, targeting early stage R&D of potentially disruptive technologies, however, could help to jump start competing chemistries "to address some of the shortcomings of lithium ion batteries" for both stationary energy storage and electric transportation, Babinec added in an interview.
Renewables integration imperative
Lithium ion batteries "are not fundamentally stable and safe," Babinec said, because of their flammable electrolyte. The materials and technology used to make Li-ion batteries safe for many different applications also impair their performance, reduce their energy density, can affect cycle life, and add to their cost. Moreover, while sufficient for short-term applications, requiring storage for four hours or less, they are insufficient to meet the need for long-term, utility-scale storage as the mix of intermittent solar and wind energy grows from 10% to 20% of grid power in many locations today to surpass 50%. "When that happens, the need for long-duration storage is going to be very evident and the [technologies] that go beyond five hours," such as flow batteries, will become increasingly important, Babinec said.
"Between five and eight hours is really our sweet spot," Craig Evans, CEO and founder of storage start-up ESS Inc., said in an interview. The developer of iron flow batteries on Dec. 12 said it had raised $13 million in an ongoing Series B round led by German chemicals giant BASF SE. The investment, which comes on top of a $3.2 million Series A round in 2015 and a $2.3 million grant from ARPA-E in 2012, will help expand the capacity of the company's plant near Portland, Ore., to 900 MWh per year.
ESS batteries, Evans claimed, are "probably the lowest cost, particularly if you look at levelized cost." Lazard Ltd.'s latest analysis of levelized cost of storage estimates flow batteries based on vanadium as low as $184/MWh for grid-scale storage, lower than lithium ion. Iron flow batteries will beat that, Evans asserted. "We are shipping at 6 cents per kWh [or $60/MWh] now, and we expect to be down to 4 cents per kWh in 2018, 2019 for renewables integration."
Iron flow technology, which relies on iron as the active material along with a salt water-based solution, also avoids the environmental and ethical issues associated with other battery chemistry, Evans said. Li-ion batteries, for instance, use cobalt — a "conflict metal" concentrated in the war-torn Democratic Republic of the Congo, extracted by mining companies that have come under increasing scrutiny.
Walk away from lithium ion?
To be sure, exotic battery ambitions often do not pan out, as the failures of several highly touted startups within the past year attest. To avoid more flameouts, ARPA-E is funding numerous teams of research scientists and companies vying to boost the energy density of batteries, and the range of electric vehicles, beyond what is possible with lithium ion. The agency has funded 10 groups currently working on lithium metal as an alternative anode material. Today's lithium ion batteries that use lithium only in cathodes reach energy densities below 300 Wh/kg, Babinec explained, with a practical limit at around 320 Wh/kg. Batteries with lithium metal anodes could go much higher.
One recent ARPA-E alum, Colorado-based Solid Power Inc., is working with automaker Bayerische Motoren Werke Aktiengesellschaft, or BMW, to develop a liquid-free version of the lithium metal battery, the company revealed on Dec. 18.
Despite their progress, whether developers of lithium metal, flow batteries and other advanced energy storage technologies can seriously compete for market share with lithium ion remains to be seen. In the meantime, commercial suppliers of Li-ion batteries will continue to get the most out of their current technology platforms. In November the Samsung Advanced Institute of Technology, working with battery supplier Samsung SDI Co. Ltd., unveiled a new "graphene ball" material that could enable charging of lithium ion batteries at five times the current speed.
The main challenge for alternative approaches is that lithium ion has "proven to be so commercially viable," Linh Tran, a sales manager at Li-ion battery developer LG Chem Ltd., said at the conference in San Francisco. "The automotive [industry] is so aggressive with technology improvements, cost improvement ... and so you know the technology is going to continue to be driven at a rapid pace."