- Solid-state battery technologies offer major performance and safety improvements over lithium-ion, positioning them as an attractive candidate for the next generation of battery technologies.
- Large manufacturers and startups are both racing to deliver cell chemistries that are both performant and inexpensive to produce.
- While the technology is promising, the challenge of working with solid-state materials has made finding an economically viable path to mass production incredibly difficult.
Solid-state Batteries Today
With the advent of electric vehicles (EVs) and grid energy storage, demand for longer-lasting batteries with higher energy densities continues to grow immensely. Unfortunately, battery technology has not enjoyed the same compounding performance improvements as technologies like computational processing, and despite the ongoing innovation in lithium-ion batteries, there remain a number of barriers to higher capacities and lowered charge times.
While the theoretical power-density to weight ratio of conventional lithium-ion batteries has yet to reach its limits, research scientists and major corporations are continuously looking beyond the barriers of lithium-ion chemistry. As the name suggests, solid-state batteries replace the flammable liquid electrolyte in lithium-ion batteries with a solid material, generally a polymer or ceramic compound. While solid-state batteries have had limited success thus far, one of the most cited themes among battery researchers in recent years has been the promising introduction of lithium-metal anodes as a replacement to conventional graphite or silicon. This race to deliver solid-state lithium-metal batteries as the next generation of energy storage chemistries could theoretically double energy density while significantly reducing charge time .
While solid-state batteries are positioned as a novel technology, the chemistry was first pioneered in the 1950s (Sphere) and is now being reconsidered as a potentially safer alternative to lithium-ion batteries. A number of startups and large companies working on these chemistries, like Toyota and Dyson, have come out with bold promises of batteries that will push EV range over 500 km and charge from 0–100% in 10 minutes (Nikkei Asia), all while remaining fire-retardant. While these batteries are already produced for small-scale specialty applications, the question remains whether they will be able to achieve commercial viability for mass production.
R&D in Solid-State Batteries
R&D in the field of solid-state batteries has taken off in recent years, demonstrating the immense potential for performance enhancements in both EVs and portable devices. The Faraday institution projects by 2040, solid-state battery demand will reach nearly 2000 GWh, and while these batteries will find a place in specialty applications such as small electronics and aircraft, the vast majority of their market share will be derived from EV growth.
A recurring theme in the solid-state battery space has been ongoing partnerships between large car manufacturers and R&D startups. In 2018, Hyundai partnered with US-based startup, Ionic Materials, a company working to advance EV batteries using solid-state polymer electrolytes and low-cobalt cathodes which are capable of conducting ions at room temperature (Hyundai). Alongside BMW and Ford, Hyundai also invested in Solid-Power (Elektrek), a US-based startup that began shipping prototype solid-state batteries and looks to be one of the most formidable contenders in the space (Solid Power).
While 2020 has been turbulent, the year has been a highlight for opportunities in the solid-state battery field. Earlier in the year, Volkswagen was reported to have invested another $200 million into QuantumScape, the Silicon Valley company recently listed on the NYSE that has been quietly developing these batteries for the past 10 years. Perhaps the industry’s most noteworthy brand, QuantumScape’s recently published anode-free cell design has reportedly overcome the complications of lithium-metal solid-state batteries while remaining cost-friendly.
On top of the hype surrounding QuantumScape’s developments, Toyota had planned to unveil a solid-state battery-powered vehicle at the (now cancelled) 2020 Olympics, stating that the company was on track to produce these batteries by 2025 (Autoblog). The once largest car manufacturer has since come out to announce that these ‘game-changing’ batteries will be debuted in 2021.
The future for solid-state batteries certainly looks promising, however it remains largely uncertain whether these projects and partnerships will amount to more than public relations pieces. Although the prototypes now being pushed out may be viable for specialty applications, if the technology is expected to compete with lithium-ion, the viability of mass production will be the deciding factor in their success.
The Challenges of Commercialization
As these companies race to be the first to market with a cell that can outperform everything currently available, raw material and production costs appear to be a more substantial challenge than the chemistry of developing a high-performing cell. One of the strongest points of solid-state battery critics are the huge investments that have been spent trying to develop them with little success to show.
Companies like Apple, Bosch, and Dyson, have poured billions of dollars into R&D on solid-state batteries, each failing to find a viable path to commercial production. In 2017, Dyson announced that it would spend $2.6 billion to produce a car powered by solid-state batteries in three years, eclipsing the $2.5 billion that Tesla Motors had spent in R&D between 2012 and 2016 (BNEF). In 2019, Dyson killed the project after failing to make a commercially viable car (Tech Crunch).
Cell Architecture Challenges
While solid-state batteries offer a range of performance improvements over lithium-ion batteries, they come with their own challenges that will need to be overcome through collaboration between research labs and advanced manufacturers. Because the electrolyte connecting the anode and cathode is a solid material, ensuring consistent adherence in the electrode-electrolyte interface becomes an incredibly difficult task, especially when paired with the demand for fast-charging batteries. If contact at the interface is weakened or broken, the performance of the battery may suffer or worst-case, short-circuit, rendering it useless.
In a promising news release, QuantumScape published its solid-state battery cell architecture, which interestingly makes use of a ceramic electrolyte, suggesting that the company has overcome the conformal contact issue, realized the anode-free target and produce these cells at scale.
Cell Materials Challenges
In order to maintain strong conductivity throughout cycling, solid-state batteries require various additives and binders within their layers. Adding to the complexity, the materials are also required to be kept under pressure in order to maintain contact throughout charging and discharging cycles. The challenge of maintaining a strong contact is compounded by the natural expansion and contraction of materials during charging and discharging cycles. If the expansion and contraction weakens the connection over time, the cycle life and performance of the cell can suffer (Springer Professional).
There is also the issue of these batteries achieving the same (or better) fast charging capabilities compared to lithium-ion. One of the biggest challenges of solid-state batteries is their low current conductivity and consequently slow rate of charge. Scientists have been making strides toward this goal, however, with the Jülich research lab developing a solid-state cell that can charge in under 1 hour, rather than the typical 10–12 hours they would typically require (Science Daily).
Performance vs. Production Cost
Tradeoff between performance and production-cost is a huge contention for solid-state battery manufacturers. While ceramic electrolytes generally offer higher performance metrics and require less expensive precursors, they can be more difficult and potentially more expensive to process. This has led developers to often favor polymer-based electrolytes, which tend to be simpler and less expensive to process, making them more apt for manufacturing despite lower performance metrics.
Business Transformation Challenges
A point that certainly raises some doubts about the potential of solid-state batteries is the lack of attention that Tesla Motors has paid to their development. As a leader in battery technology and advanced manufacturing, why might the company have opted to work toward increasing its lead in Lithium-ion — a space it already dominates — rather than working on solid-state batteries?
Rather than overhauling the company’s existing strategy, Tesla has sought to optimize its existing technology, one notable step being the introduction of its tabless battery system this fall (Clean Technica), as well as their decision to focus on developing silicon anodes for conventional lithium-ion batteries, which will improve energy density by 20% while reducing costs by another 5% (Barrons). To speculate on this strategy, Tesla’s limited flexibility to shift its core value chains might have pushed it to allow other companies to do the heavy lifting when it comes to new R&D. Both knowing that Tesla has a significant advantage in the lithium-ion battery market, conventional car companies working on solid-state batteries may be opting to skip a generation of technology in developing their EV’s as they can innovate while continuing to service their core business.
The Future of Solid-state Batteries
Will solid-state batteries ever be cost-competitive?
While solid-state batteries may offer improved safety and performance over lithium-ion, finding cost-effective means of processing the electrolytes and achieving economies of scale are key to securing their competitive position. At the same time, solid-state batteries need to be able to keep up with the cost reductions in lithium-ion batteries that are now targeting $100/kWh as more factories, capable of producing gigawatt hours of cells begin to ramp up over the coming years. At the current pace, it seems unlikely that we will see a solid-state battery giga-factory before 2030, however demand and innovations in advanced manufacturing may accelerate this timeline.
One of the pioneering companies in solid-state technology is the UK-based, Ilika. In a recent presentation, the company claimed that the major limiting factor to producing cost-competitive solid-state batteries are supply chain investments in new chemical facilities. Already having commercialized small-scale solid-state batteries for applications in medical devices and sensor-based technologies, Ilika is working to develop cells for the EV market and claim that these cells can be cost-competitive. In a presentation given this year, Ilika projected that solid-state battery cells could be on par with lithium-ion batteries by 2025. It should be noted, however, that this estimate does not account for the continuing cost reduction in lithium-ion cells, and considers only the raw material costs of solid-state battery cells.
What will it take for solid-state batteries to succeed?
While innovations like Tesla’s tabless design and the introduction of silicon anodes will produce marginal improvements in Lithium-ion performance, the adoption of new chemistries and cell architectures will need to be introduced to overcome the safety and energy density issues that remain.
Based on the development thus far, demonstrating high-performance solid-state battery chemistries does not appear to be nearly as challenging as producing them at scale. The success of new cells remains largely dependent on their cost of production, particularly as the cost of lithium-ion batteries continues to drop below $100/kWh by 2024.
Summary
Although there remain a number of barriers to the commercialization of solid-state batteries, research and innovation will surely find a way toward higher performance energy storage. While solid-state batteries may not be part of Tesla’s near term strategy, Elon Musk has noted that lithium-metal anodes are key to achieving substantial performance improvements over the current technology (Solid Power), especially when paired with solid electrolytes.
With the industry continuing to gain confidence in the technology, the opportunity is certainly being assessed and it seems that large chemical manufacturers will play a deciding role in the success of solid-state battery commercialization should they choose to move forward with investment in new infrastructure to support the industry. For now, while momentum and hope for the technology’s success continues to build, the question remains whether cost reductions will take place fast enough for widespread use in EV’s or whether solid-state battery technology will be limited to niche applications.
Joshua Strub is a Canadian Master’s graduate from Sciences Po Paris, specializing in global energy markets, natural resource economics, and sustainable finance. He now works as a business developer and analyst at Sphere Energy, a Paris-based company developing specialized instruments for testing solid-state batteries, flow systems, and catalysis.
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