Solar Energy

Inexpensive battery charges rapidly for electric vehicles

Published

4 years ago

February 8, 2021

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Inexpensive battery charges rapidly for electric vehicles

Range anxiety, the fear of running out of power before being able to recharge an electric vehicle, may be a thing of the past, according to a team of Penn State engineers who are looking at lithium iron phosphate batteries that have a range of 250 miles with the ability to charge in 10 minutes.

“We developed a pretty clever battery for mass-market electric vehicles with cost parity with combustion engine vehicles,” said Chao-Yang Wang, William E. Diefenderfer Chair of mechanical engineering, professor of chemical engineering and professor of materials science and engineering, and director of the Electrochemical Engine Center at Penn State. “There is no more range anxiety and this battery is affordable.”

The researchers also say that the battery should be good for 2 million miles in its lifetime.

They report Jan. 18 in Nature Energy that the key to long-life and rapid recharging is the battery’s ability to quickly heat up to 140 degrees Fahrenheit, for charge and discharge, and then cool down when the battery is not working.

“The very fast charge allows us to downsize the battery without incurring range anxiety,” said Wang.

The battery uses a self-heating approach previously developed in Wang’s center. The self-heating battery uses a thin nickel foil with one end attached to the negative terminal and the other extending outside the cell to create a third terminal. Once electrons flow it rapidly heats up the nickel foil through resistance heating and warm the inside of the battery. Once the battery’s internal temperature is 140 degrees F, the switch opens and the battery is ready for rapid charge or discharge.

Wang’s team modeled this battery using existing technologies and innovative approaches. They suggest that using this self-heating method, they can use low-cost materials for the battery’s cathode and anode and a safe, low-voltage electrolyte. The cathode is thermally stable, lithium iron phosphate, which does not contain any of the expensive and critical materials like cobalt. The anode is made of very large particle graphite, a safe, light and inexpensive material.

Because of the self-heating, the researchers said they do not have to worry about uneven deposition of lithium on the anode, which can cause lithium spikes that are dangerous.

“This battery has reduced weight, volume and cost,” said Wang. “I am very happy that we finally found a battery that will benefit the mainstream consumer mass market.”

According to Wang, these smaller batteries can produce a large amount of power upon heating – 40 kilowatt hours and 300 kilowatts of power. An electric vehicle with this battery could go from zero to 60 miles per hour in 3 seconds and would drive like a Porsche, he said.

“This is how we are going to change the environment and not contribute to just the luxury cars,” said Wang. “Let everyone afford electric vehicles.”

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Solar Energy

HZB sets new efficiency record for CIGS perovskite tandem solar cells

Published

46 minutes ago

February 5, 2025

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HZB sets new efficiency record for CIGS perovskite tandem solar cells

by Robert Schreiber

Berlin, Germany (SPX) Feb 05, 2025

Researchers at Helmholtz Center Berlin for Materials and Energy (HZB) and Humboldt University Berlin have developed a CIGS-perovskite tandem solar cell that has set a new world record for efficiency, achieving 24.6%. The performance of the cell has been officially certified by the Fraunhofer Institute for Solar Energy Systems.

Thin-film solar cells, such as those based on copper, indium, gallium, and selenium (CIGS), require minimal material and energy to manufacture, making them an environmentally friendly alternative to conventional silicon-based solar cells. CIGS thin films can also be applied to flexible substrates, expanding their potential applications.

The new tandem solar cell developed by HZB and Humboldt University combines a CIGS bottom cell with a perovskite top cell. By optimizing the contact layers between these two components, the research team successfully increased efficiency to a record-breaking 24.6%. This milestone was confirmed by the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany.

This achievement was made possible through a collaborative effort among researchers. The top cell was developed by Thede Mehlhop, a master’s student at TU Berlin, under the supervision of Stefan Gall. The perovskite absorber layer was created in the joint laboratory of HZB and Humboldt University Berlin, while the CIGS sub-cell and contact layers were fabricated by HZB researcher Guillermo Farias Basulto. Additionally, the KOALA high-performance cluster system at HZB was used to deposit the perovskite and contact layers in a vacuum.

“At HZB, we have highly specialized laboratories and experts who are top performers in their fields. With this world record tandem cell, they have once again shown how fruitfully they work together,” said Prof. Rutger Schlatmann, spokesman for the Solar Energy Department at HZB.

HZB has a strong track record in achieving world records in solar cell efficiency, including past accomplishments in silicon-perovskite tandem cells and now in CIGS-perovskite tandem technology.

“We are confident that CIGS-perovskite tandem cells can achieve much higher efficiencies, probably more than 30%,” said Prof. Rutger Schlatmann.

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Solar Energy

Advancing safer lithium energy storage

Published

1 day ago

February 4, 2025

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Advancing safer lithium energy storage

by Erica Marchand

Paris, France (SPX) Feb 04, 2025

Charging our phones has become so routine that we rarely reflect on the breakthrough that made it possible. Rechargeable lithium-ion batteries, introduced commercially in the 1990s, propelled a technological revolution that earned their creators the 2019 Nobel Prize in Chemistry. This key innovation underpins the functionality of today’s smartphones, wireless headphones, and electric vehicles, making them both financially and environmentally practical.

As our devices grow more advanced, the demand for batteries that pack more power while remaining safe continues to rise. Yet engineering such power sources is far from simple. One promising design is the lithium metal battery, which could deliver more stored energy than standard battery types. Unfortunately, its potential is curtailed by a persistent issue: the emergence of tiny threads, or dendrites, that accumulate with each charge. When dendrites build up, they can form metallic connections that degrade battery functionality and pose a serious fire hazard. Until recently, researchers had limited approaches to probe and understand dendrite formation. In a new study led by Dr. Ayan Maity in the lab of Prof. Michal Leskes at the Weizmann Institute of Science’s Molecular Chemistry and Materials Science Department, scientists developed a novel method to identify the factors that spark dendrite growth, as well as to rapidly evaluate various battery components for improved safety and performance.

Rechargeable batteries function by allowing positively charged ions to migrate between the anode (negative electrode) and the cathode (positive electrode) through an electrolyte. Charging forces the ions back into the anode, counter to the usual flow in a typical chemical reaction, thus preparing the battery for another cycle of use. Lithium metal batteries take a different approach by employing a pure lithium metal anode, enabling higher energy storage. However, lithium metal is chemically reactive and quickly forms dendrites when it interacts with the electrolyte. Over time, enough dendrites can short-circuit the battery and raise the likelihood of combustion.

One way to avoid fire risks is to replace the volatile liquid electrolyte with a solid, nonflammable one, often comprising a polymer-ceramic composite. While altering the ratio of polymer to ceramic can influence dendrite growth, finding the ideal formulation remains a challenge for extending battery life.

To investigate, the team employed nuclear magnetic resonance (NMR) spectroscopy, a standard tool for pinpointing chemical structures, and tracked both dendrite formation and the chemical interplay within the electrolyte. “When we examined the dendrites in batteries with differing ratios of polymer and ceramic, we found a kind of ‘golden ratio’: Electrolytes that are composed of 40 percent ceramic had the longest lives,” Leskes explains. “When we went above 40 percent ceramic, we encountered structural and functional problems that impeded battery performance, while less than 40 percent led to reduced battery life.” Intriguingly, batteries with that optimal ratio displayed more dendrites overall, but those dendrites were effectively confined in a way that prevented destructive bridging.

These insights prompted a larger question: what halts the extension of the dendrites? The team hypothesized that a thin covering on the surface of dendrites, called the solid electrolyte interphase (SEI), might be crucial. This layer, formed when dendrites interact with the electrolyte, can affect how lithium ions travel through the battery, and it can also either prevent or accelerate the movement of harmful substances between electrodes. Both of these factors, in turn, can stifle or foster further dendrite development.

Probing the chemical composition of such thin SEI films is inherently difficult, since they measure only a few dozen nanometers thick. The researchers tackled this problem by enhancing the signals in their NMR data using dynamic nuclear polarization. This specialized technique leverages the strong spin of polarized lithium electrons, bolstering signals from the atomic nuclei in the SEI and exposing its chemical makeup. Through this refined lens, the researchers discovered precisely how lithium metal interacts with polymer or ceramic materials, revealing that certain SEI layers can simultaneously improve ion transport and block hazardous substances.

Their findings pave the way to design sturdier, safer, and more powerful batteries that will store greater energy for a longer duration with reduced environmental and economic costs. Such next-generation batteries could power larger devices without having to increase the physical size of the battery itself, while also extending the battery’s life cycle.

“One of the things I love most about this study is that, without a profound scientific understanding of fundamental physics, we would not have been able to understand what happens inside a battery. Our process was very typical of the work here at the Weizmann Institute. We started with a purely scientific question that had nothing to do with dendrites, and this led us to a study with practical applications that could improve everybody’s life,” Leskes says.

Research Report:Tracking dendrites and solid electrolyte interphase formation with dynamic nuclear polarization-NMR spectroscopy

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Solar Energy

Role of barrier films in maintaining the stability of perovskite solar cells

Published

2 days ago

February 3, 2025

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Role of barrier films in maintaining the stability of perovskite solar cells

by Riko Seibo

Tokyo, Japan (SPX) Jan 31, 2025

Perovskite solar cells (PSCs) offer a promising advancement in renewable energy due to their high efficiency, lightweight, and flexible properties. However, their commercial viability is challenged by their vulnerability to environmental conditions, particularly heat and humidity.

To tackle this issue, a research team led by Professor Takashi Minemoto, a Fellow at the Ritsumeikan Advanced Research Academy, alongside Dr. Abdurashid Mavlonov from Ritsumeikan University’s Research Organization of Science and Technology and Dr. Akinobu Hayakawa from Sekisui Chemical Co., Ltd., conducted an in-depth study on the durability of PSC modules under harsh environmental conditions. Their research, published in Volume 286 of *Solar Energy* on January 15, 2025, was first made available online on December 17, 2024.

Discussing the study’s motivation, Prof. Minemoto stated, “Perovskite solar cells stand out as particularly promising due to their low-temperature wet-coating process and compatibility with flexible substrates, offering unique opportunities for the solar industry. However, the stability of perovskite is weak compared with conventional material, which can be improved by fabrication processes such as encapsulation with barrier films.”

For this research, the team analyzed the durability of flexible PSC modules made from methylammonium lead iodide (MAPbI3) and encapsulated them using polyethylene terephthalate (PET) substrates with barrier films of varying water vapor transmission rates (WVTR). These modules were subjected to a damp heat test at 85 C and 85% relative humidity to replicate long-term outdoor conditions.

After 2,000 hours of exposure, researchers measured photovoltaic (PV) performance and assessed module degradation using current-voltage characteristics, spectral reflectance, and electroluminescence imaging. The findings confirmed that high humidity caused the MAPbI3 layer to break down into lead iodide, obstructing charge transport and significantly reducing the efficiency of the PSC modules.

Moreover, the study demonstrated the critical role of barrier films in maintaining module stability. Notably, the module with the lowest WVTR barrier retained 84% of its initial power conversion efficiency, whereas modules with higher WVTR deteriorated rapidly, ceasing to function after just 1,000 hours.

“Our study is the first to report the durability of encapsulated flexible MAPbI3-based PSC modules. When considering solar energy applications for walls and rooftops with weight limits or for mobile platforms, flexible PSCs are a great alternative to the traditional silicon panels. Insights from our study could help industries optimize these modules for highly stable and durable constructs,” explained Prof. Minemoto.

This research underscores the essential role of barrier films in ensuring the long-term viability of flexible PSC modules, which could reshape the photovoltaic industry. By enabling energy generation in a variety of locations, these advancements help alleviate pressure on power grids. Additionally, enhancing the durability of PSCs expands their usability across different environments, further accelerating the global transition to cleaner and more sustainable energy solutions.

Research Report:Perovskite solar cell modules: Understanding the device degradation via damp heat testing