Originally published on Apricum Group.
By Florian Haacke and Dr. Hendrik Kienert
Driven by an increasing share of renewable energy and e-mobility, the energy storage market is exhibiting substantial growth, which Apricum expects will continue for the foreseeable future. This not only presents new opportunities for energy storage system suppliers, but also for material and polymer players who can add substantial value to these emerging markets by providing tailored components to achieve performance, cost and safety improvements.
The integration of intermittent renewable energy sources in the power mix for a growing number of countries is driving demand for stationary storage solutions that can accommodate specific local market and infrastructure conditions, e.g., to stabilize the grid, to bridge different points in time of electricity generation versus consumption and to compensate for insufficient grid expansion.
A rapidly growing market
While the global annual market size of stationary storage amounted to 700 MWh in 2015, Apricum expects this figure to grow to 14 GWh by 2020. Within the same time frame, battery demand for e-mobility is projected to reach 35 GWh per year.
These high growth applications create a significant increase in demand for lithium-ion batteries with high energy density that allow for deeper discharging than the incumbent lead-acid batteries.
Polymer materials in batteries crucial for performance and safety
Lithium-ion batteries are composed of multiple functional components. So far, industry focus has mostly been on cathodes and anodes, which determine the principle cell chemistry. Much research has been directed into optimizing electrodes and customizing them for specific requirements. Now, we are seeing the remaining cell components – often polymer-based – shift more into the industry’s spotlight. Improved materials offer potential for increased technical performance, enhanced durability and safety standards. Collectively, the following polymer-based Li-ion components should be considered.
Separators: Separators are placed between the electrodes and provide electrical insulation, preventing the cell from short-circuits and allowing for transmission of electrolyte ions. Their key material properties are related to chemical/physical stability and ease of ion transport. Improvement of their performance parameters contributes to the safety of the batteries (especially the prevention of thermal runaway) and may yield higher power and energy densities.
Binders: Binders are mixed into the electrode materials to ensure good cohesion of the electrode particles and good adhesion to the current collector. Key material properties are adhesion/cohesion strength, stability and ease of processing. The quality and share of binder materials have a significant impact on energy and power density of the battery.
Electrolytes: Electrolytes of lithium-ion batteries fill the space between the electrodes and contain the ions for the intercalation process. Electrolytes usually consist of conducting salts, organic aprotic solvents and additives. In some cell concepts, a polymer electrolyte can replace the traditional electrolyte and the separator. Such lithium polymer cells have the advantage of an improved safety level, e.g., with respect to the formation of dendrites and thus the risk of inflammation.
The cost share for separators, binders and electrolytes alone amounts to about a third of the total value of lithium-ion battery materials. Thus, the overall revenue potential for these components is substantial.
The market for energy storage in stationary applications and in the field of e-mobility is on the verge of “taking off” and has different requirements compared to those of the traditional battery industry. While established polymer solutions are on the market, Apricum expects significant new developments geared towards improved performance/cost ratios. Parallels can be drawn with the dynamics in PV industry films and components over the past five years. Moreover, customized components for specific cell chemistries provide attractive growth opportunities for new entrants in the energy storage space.
Energy storage materials: polyolefin films, nonwovens and fluoropolymer binders
Separators for lithium-ion batteries are traditionally made out of polyolefin films, either polyethylene (PE) or polypropylene (PP). The most prominent safety challenge of thermal runaway leading to inflammation is addressed by a triple-layer concept of PE layered between PP where the inner layer melts at a lower temperature and “shuts down” the battery discharging process as a safety feature. Further improvements of separator safety have been achieved with inorganic additives or coatings to reach higher stability.
A very different approach relies on micro and nanofiber nonwovens that target higher stability levels and are in most cases based on polyester (PET). Other base materials include cellulose and acrylic copolymers. The fine tuning of material properties is possible via coating or impregnation with inorganic materials. This potentially offers synergies with other end-products for nonwoven specialist players.
PVDF is the main basis for binders in different lithium-based cathodes while styrene butadiene copolymer (SBR) is the preferred solution for graphite anodes. Remaining challenges related to PVDF are the use of organic solvents, usually NMP, and other associated risks. Materials players are actively working to mitigate these risks and prepare a pipeline of innovative binder products.
For polymer electrolytes, the most common material choices are based on polyethylene oxide (PEO) that is typically mixed with suitable conducting salts, e.g., LiTFSI or LiFSI.
Tailored materials offer differentiation potential
When entering the battery material space, polymer producers, film extruders and coating specialists have the opportunity to differentiate by offering solutions for existing and future technical challenges.
Current developments in energy storage thus provide significant opportunities for raw material suppliers, film extruders and coating specialists. In order to structure an effective market entry and development strategy, a solid understanding of the market dynamics and trends is required, as well as robust projections of technology roadmaps. This includes the emergence of new types of batteries and of supercapacitors, the latter allowing for high power charging or discharging for a short period of time, especially in the area of mobility.
Apricum’s materials practice supports its clients at each relevant step in evaluating and implementing activities that provide innovative materials for energy storage applications. Specific focus areas include:
- Quantification of future global market size and dynamics, segmented along cell chemistries and applications (market segmentation)
- Analysis of the global competitive landscape
- Assessment of technology roadmaps, future technical requirements by market segment
- Market entry and development strategy design
- Partnering and transaction advisory (M&A) to reduce time to market
For further information, please contact Florian Haacke, partner and head of Apricum’s solar and energy storage materials practice.
Reprinted with permission.
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