Emerging Materials for Next-Generation Energy Storage Devices

Published on 27 February 2024 at 22:44

Emerging Materials for Next-Generation Energy Storage Devices

As the world transitions to sustainable energy, advanced storage solutions are critical to provide 24/7 electricity without interruption. Examination of promising emerging materials for energy storage applications will including batteries, capacitors, and thermal storage systems. Key materials evaluated include silicon, lithium metal, and lithium-sulfur for battery electrodes, novel electrolytes, phase change materials, firebrick, concrete, sand, rock, graphite, and more.

Each material is assessed in terms of its advantages, challenges, current technology readiness levels, and projected future performance. Key findings show that while no single material has yet dominated, ongoing research across many fronts brings optimism that cost-effective, high-performance energy storage is within reach. Realizing next-generation storage capabilities will require a collaborative ecosystem across academia, industry, and policymakers. With sustained effort, emerging materials can enable affordable, reliable, and sustainable energy storage critical to a clean energy future.

 

Introduction 

As renewable energy grows as a fraction of electricity generation, energy storage becomes increasingly vital. Solar and wind power are intermittent, so stored energy helps smooth out supply and demand mismatches. Energy storage is also crucial for electric vehicle adoption and grid stability as traditional synchronous generators decline. According to projections by the International Renewable Energy Agency, global energy storage capacity needs to grow from under 10 GW today to over 600 GW by 2030 to support decarbonization goals. This enormous growth depends on continued technology innovation to deliver cost-effective storage solutions.

 

This Informative Solar report focuses on emerging material advances that can enable next-generation energy storage capabilities. The materials are segmented into categories based on the storage principles: electrochemical like advanced batteries, electrical like capacitors, and thermal like phase change materials. Each section provides technical background on the storage mechanisms and assesses the benefits and limitations of various new material approaches. This Report aims to synthesize cutting-edge research in academia and industry to highlight promising directions and guide future work for both researchers and policymakers.

 

Advanced Battery Materials

Rechargeable lithium-ion batteries are the dominant battery technology for electric vehicles and grid-scale storage due to their high energy density compared to other commercial chemistries. But lithium-ion technology has almost reached its theoretical limits, so new materials are needed to significantly improve performance and cost.

 

Silicon anodes can provide 10x higher capacity than typical graphite anodes. However, silicon suffers from fracturing and large volume changes during cycling, causing rapid capacity fading. Strategies like silicon-graphite composites, nanoscale silicon, and advanced binders and electrolytes help mitigate these issues. Amprius and Enovix have developed high-silicon anodes nearing commercialization. Further development is focused on scaling up fabrication while maintaining consistency and cycle life.

 

Lithium metal anodes can enable very high energy density batteries. But dendritic lithium growth and low Coulombic efficiency currently hinder viability. Approaches like highly concentrated electrolytes, nanoscale scaffolding, and hybrid designs show promise to stabilize these anodes. Solid-state batteries with lithium metal anodes and solid electrolytes could also boost safety and energy density, although manufacturability challenges remain. QuantumScape and Solid Power have prototype solid-state batteries with lithium anodes expected to reach market in the mid-2020s.

 

Lithium-sulfur cathodes offer 5-10x higher capacity than typical lithium cobalt oxide cathodes. However, the sulfur cathode dissolves polysulfide intermediates that shuttle and react on the anode, decreasing life. Carbon nanotubes, graphene oxide, and polymer binding materials help contain the polysulfides. Oxis Energy has demonstrated 500 cycles with 85% capacity retention, and Sion Power achieved 400 cycles at 60% retention, showing significant progress for this technology.

 

In general, tradeoffs exist between high energy density designs like lithium metal anodes and high cycle life designs like lithium iron phosphate cathodes. Grid storage may favor cycle life, while electric vehicles demand maximal energy density. Continued materials innovation is critical to enable specialized designs optimized for each application.

 

Capacitor Materials  

Electrochemical capacitors, also known as supercapacitors, offer an alternative energy storage solution complementary to batteries. They store charge directly on the electrode surfaces rather than in bulk chemical phases, so charge rapidly but hold less total energy than batteries. Their high power density suits applications like regenerative braking.

 

Graphene has enormous surface area and high conductivity, making it promising as a capacitor electrode material. However, restacking limits accessible surface area. Integrating graphene into porous scaffolds or 3D architectures helps realize its potential. Laser-induced graphene offers a scalable synthesis approach. Companies like Skeleton Technologies have developed graphene materials targeting a 5-10x increase in energy density compared to activated carbon supercapacitors.

 

MXenes are a family of 2D transition metal carbides and nitrides with metallic conductivity and hydrophilic surfaces enabling high ion mobility between layers. Early results demonstrate excellent charge storage capacity in MXene electrodes. Further work is focused on understanding charge storage mechanisms and synthesizing new compositions.

 

Most supercapacitors use electrolytes like acetonitrile or propylene carbonate. Ionic liquids are molten salts composed entirely of ions that can offer 3-4x wider stable electrochemical windows, enabling increased energy density. Challenges include high viscosity and cost, but new designs like supported ionic liquid layers help address these issues.

 

Thermal Storage Materials

Thermal energy storage is an often overlooked but promising electricity storage pathway. Heat or cold can be stored in materials and then discharged on demand to meet electricity, heating, or process needs. Phase change materials (PCMs) are particularly attractive thermal storage media due to their high latent heat capacity at useful temperatures.

 

Organic PCMs like paraffin waxes and fatty acids are inexpensive but have low thermal conductivity and flammability concerns. Inorganic PCMs, such as salts and eutectic mixtures, have higher conductivity and are nonflammable, but often contain corrosive hydrated salts. Novel composites like paraffin/expanded graphite combine the benefits of both categories. Iron nitrate ammonia complexes show excellent stability and energy storage density with tunable melting points by varying ammonia ligands.

 

Firebrick made of refractory ceramic has been studied as an inexpensive and durable solid media thermal storage option. Firebrick can withstand repeated high temperature heat storage cycles. It could be used to store excess renewable electricity as heat in concentrated solar power plants or industrial processes. Recovered heat could generate steam or electricity on demand. 

 

Concrete containing PCMs can also provide solid media thermal storage. The concrete stabilizes the PCM while allowing good heat transfer. This also enables structural storage elements like walls or foundations to passively store energy. Smart material design will be needed to account for PCM volume expansion.

 

Future Outlook

This Informative Solar report highlights the tremendous ongoing materials innovation pushing energy storage capabilities forward. Silicon, lithium metal, lithium-sulfur, and beyond are enabling dramatic leaps in battery performance and cost over the next 5-10 years. Capacitors and thermal storage solutions also show promise in suitable niches.

 

However, significant work remains to scale up and optimize these technologies. Collaboration between researchers, industry, and policymakers is vital to accelerate development and commercialization. Affordable and reliable energy storage is crucial to enabling the global energy transition. The materials described in this report provide realistic and exciting paths to make this vision a reality. With continued effort, innovation, and investment, a cleaner energy future awaits.

 

- INFORMATIVE SOLAR

 

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