Improved battery storage technologies
Power and renewables Maritime

Battery storage is expected to play a critical role in the energy transition, in the fields of electric mobility as well as a vital component offering flexibility and supporting variable renewable energy to the power grid.

Many battery chemistries remain viable, but advancements in Li-ion have led to market dominance, covering 95-99% of market deployments in recent years. Much of this can be credited to Li-ion Nickel-Manganese-Cobalt (NMC) batteries, which have a good balance of energy density and power and comprise much of the present growth in battery electric vehicles in the automotive sector. Brands such as LG and Samsung are predominantly NMC batteries. Tesla advertises their battery as a Nickel Cobalt Aluminum (NCA) battery. As these batteries get cheaper in cost (reducing tenfold over the last decade), they become more viable for long duration applications by simply stacking them in larger quantities, such that demands for power versus energy becomes covered entirely by the NCM battery compared to other energy storage technologies.  Energy density in Li-ion Iron Phosphate (LiFePO4) batteries has also been increasing over time with similar cost declines, making LiFePO4 also a viable candidate for both short and long duration functions.

Changing the battery chemistry type to Li-S, Li-O or Mg-Ion has the potential to improve energy density by a factor of 2-31. In addition, we can expect faster and increased number of charging cycles. Such improvements are especially important for mobility applications. Changing the liquid electrolyte to solid as some of the solutions suggest would increase the energy density and reduce risk of thermal runaway and fires that current batteries face as a risk.

However, new types and chemistries are all challenged with competing with the ever-decreasing cost of now-conventional, now-incumbent Li-ion batteries based on NCM/A chemistries. Today, these batteries have achieved low cost and increasing energy density not by leap-frogging their competition with technological breakthroughs, but with simple and persistent engineering optimization of their production methods, tooling, speeds, and efficiency.

Opportunities and market impacts

At the present rate, NCM/NCA Li-ion batteries will achieve $100/kWh at the DC level before 2030 and will likely achieve 300 Wh/kg. These rates appear linear, however if greater growth occurs, these metrics will be met much earlier.  For reference, within 10 years if the energy density of batteries is doubled, a vehicle such as the Tesla Model S won’t have 300 miles of range, but 600. Conversely, if the battery pack volume is cut in half, a Tesla Model S cost may be reduced as much as 50% because less battery is needed for the same performance, and the battery is the bulk of the vehicle cost.  For a smaller vehicle like a Tesla Model 3 or Hyundai Kona EV, range could be doubled or prices could be reduced 25-50%, indicating that a practical EV with long range will be had for a price in the $20,000’s. Thus, in our Energy Transition Outlook we outline a future where 50% of all new passenger vehicle sales in 2032 will be electric2.

Because of the strength of this incumbent technology, which is surrounded by a large, integrated supply chain that is already consolidating around general manufacturing practices, semi-standard racking solutions, contract manufacturing practices, basic electronic modularity, and containerized solutions, it is very likely that future innovation in energy storage will be forced to fit within these commercial and market constraints, i.e. new battery chemistries may look and feel like existing battery chemistries, except better.

Present day Li-ion batteries use an electrolyte in which the main ingredient, by volume, is ethylene carbonate and variations thereof. The electrolyte is designed to lend stability to both the anode and cathode. Because ethylene carbonate is flammable, it contributes to concerns for battery fires. A solid state electrolyte can be developed from ceramics, polymers, or glass and is presumed to be inflammable or at least resistant to self-ignition. The challenges in development are converting the insertion or deposition of these electrolytes to a process that is compatible with today’s manufacturing practices, all without affecting the durability or cost of the final product while adding benefits such as better energy and power density, increased safety, and higher throughput.  It is expected that early generation solid state Li-ion batteries, which are claimed to be in low-volume today, will have 400 Wh/kg. Assuming they can be advanced in the same incremental way that Li-ion is today, it may be possible to envision 400-500 Wh/kg commercial batteries by 2030, instead of 300 Wh/kg.

Soteria Battery Innovation Group (Soteria), of which DNV GL is a member, has patented a combined separator and current collector combination which can be inserted into today’s production tooling for Li-ion batteries while benefiting energy and power density3. The current collector and separator show significantly higher performance than conventional separators. Soteria has shown that a nail-punctured cell can continue operating.  The current collector is based on a metalized polymer film, and during a puncture, it retracts from the damage site rather than deforming and penetrating the separator and causing a short. Thus, the Soteria technology offers both safety and performance benefits. In addition, it can be incorporated into roll-coating processes that are used in today’s Li-ion battery manufacturing plants.

The current incremental advancement plan alone nearly guarantees substantial cost reductions and performance gains in the future. Advancements in materials compatible with today’s manufacturing processes such as substitution of liquid electrolytes with solid chemistries, or new separators and current collectors, will assure Li-ion’s dominance in battery storage.

In addition to the transition towards new electrolytes and materials, we expect improvement in charge rates through asymmetric temperature modulation4. With limited degradation of charge cycles existing batteries can add 300km range in 10 minutes which would further improve the adoption of EVs. Reference cells produced today could power an EV over 1.6 million km and last at least two decades in a grid energy storage.5

All of the above advancements will improve the value of Li-ion batteries. Even with no changes in materials at all, the next 10 years will show us electric vehicles with better performance than any conventional gasoline or diesel powered vehicle today, and energy storage systems with costs at 30-75% less than what they are today with improved safety. We’re set to experience some very rapid upsets in the energy and transportation sectors.

Risk and uncertainties

Depending on the success of battery chemistry development combined with mining/market constraints the transition will be sooner rather than later. If growth is hampered by access to feedstock materials and rampant price increases, the change will happen slower. If funding for battery research is curbed the switch will happen later, however we do not see any developments or technologies that could challenge current progress.

A challenge for EVs will be access to charging infrastructure. Rural areas without access to reliable electricity will remain areas where EVs struggle. However, overall electrification trends in combination with the expected increase in charging speed will alleviate this challenge.

Contributors

Main author: Mats Rinaldo

Contributors: Marcel Eijgelaar; Davion Hill

Editor: Peter Lovegrove

  1. RVO battery technology report
  2. DNV GL Energy Transition Outlook
  3. https://www.soteriabig.com/soteria-cell-architecture.html
  4. Asymmetric Temperature Modulation for Extreme Fast Charging of Lithium-Ion Batteries Published:October 30, 2019 DOI
  5. A Wide Range of Testing Results on an Excellent Lithium-Ion Cell Chemistry to be used as Benchmarks for New Battery Technologies. Journal of The Electrochemical Society, 166 (13) A3031-A3044 (2019). DOI: 10.1149/2.0981913jes
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