In the U.S., researchers in the Cockrell School of Engineering at the University of Texas at Austin have discovered a family of anode materials that can double the charge capacity of lithium-ion battery anodes. This means that the batteries that we use in everything from cellphones to large-scale energy storage systems could be more efficient in the future.
The new family of anode materials, which the researchers dubbed the Interdigitated Eutectic Alloy (IdEA) anode, saves time and materials by producing an anode using only two simple steps instead of the multiple steps traditionally required to mass-produce lithium-ion battery anodes.
The researchers created a foil material that is one-quarter of the thickness and half of the weight of the graphite and copper anodes used in virtually all lithium-ion batteries today. As a result, a smaller, lighter rechargeable battery could be made with the new anode in the future.
University of Texas researchers have developed a new tin-aluminum anode (right), dubbed the Interdigitated Eutectic Alloy (IdEA) anode, that provides twice the charge storage capacity of the typical copper-graphite anode (left). (Cockrell School of Engineering)
“It is exciting to have developed an inexpensive, scalable process for making electrode nanomaterials,” says Arumugam Manthiram, a professor and the director of the Texas Materials Institute, who led the team. “Our results show that the material succeeds very well on the performance metrics needed to make a commercially viable advance in lithium-ion batteries.”
Recent efforts to improve lithium-ion battery electrodes have focused on building new nanomaterials atom by atom. Manthiram and his team, which includes postdoctoral fellow Karl Kreder and materials science and engineering graduate student Brian Heligman, developed a new class of anode materials in which eutectic metal alloys are mechanically rolled into nanostructured metal foils.
Since the 1990s, the primary anode for mass-produced rechargeable lithium-ion batteries has been a graphite powder coated on a copper foil. The copper adds bulk to an electrode without improving the battery’s power and the anode requires a laborious, fastidious manufacturing process. By omitting the complicated slurry coating process, the manufacturing of the IdEA anode is drastically simplified.
Kreder, who is the lead author on the study, realized that a micrometer-scale alloy anode could be transformed into a nanomaterial using traditional metallurgical alloying processes.
“Eutectic microstructure forms naturally because of thermodynamics,” Kreder says. “Then, you can reduce the microstructure by rolling it, which is an extraordinarily cheap step to convert a microstructure into a nanostructure.” (Eutectic refers to an alloy or mixture whose melting point is lower than that of any other alloy or mixture of the same ingredients.)
The team’s resulting anodes occupy significantly less space, overcoming a critical barrier to commercializing better batteries for use in portable electronic devices like cellphones and medical devices, as well as larger applications like electric cars.
This research was published in the journal ACS Energy Letters. It was funded by a grant from the U.S. Department of Energy’s Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.
Among the other U.S. universities active in battery research are:
- Penn State University
- University of California, Irvine
- University of California, Berkeley
- Clemson University
- University of Colorado
- University of Washington
- University of Maryland
Also in the U.S., ARPA-E has picked 11 organizations for its BEEST (Batteries for Electrical Energy Storage in Transportation) program whose primary focus is development of advanced battery chemistries, architectures, and manufacturing processes with the potential to provide EV battery system level energy densities exceeding 200 Wh/kg (mass density) and 300 Wh/liter (volumetric density) at system-level costs of $250/kWh or below. The ability for proposed battery technologies to achieve system-level target metrics on a number of other key performance parameters is of significant, but secondary, importance.
It is ARPA-E’s belief that the required ambitious energy density and cost metrics for widespread adoption of EVs represent the most significant challenges and emerging technology opportunities facing battery technology development for EV applications today. The table below lists the participants in the BEEST program and their assigned projects.
The U.S. Department of Energy’s Vehicle Technologies Office focuses on reducing the cost, volume, and weight of batteries, while simultaneously improving the vehicle batteries' performance (power, energy, and durability) and ability to tolerate abuse conditions. Reaching the Office's goals in these areas and commercializing advanced energy storage technologies will allow more people to purchase and use electric drive vehicles. The Vehicle Technologies Office pursues three major areas of research in batteries:
- Exploratory battery materials research
- Applied battery research
- Advanced battery development, system analysis, and testing
In 2012, Toyota described a solid-state battery for an EV that would extend the range and reduce recharge times. Solid-state batteries have the advantages of no fire hazard, the ability to store more power in a given volume, and they can be molded into many shapes. The company is working on R&D, including the production engineering of solid-state batteries, hoping to commercialize them by the early 2020s.
In June 2017, Toyota applied for a patent on a solid-state lithium battery with improved thermal stability. This solid-state lithium battery comprises a cathode active material layer containing a cathode active material, an anode active material layer containing an anode active material, and a solid electrolyte layer formed between the cathode active material layer and the anode active material layer. The cathode active material is an oxide active material, at least one of the cathode active material layers and the solid electrolyte layers contains a sulfide solid electrolyte material. The sulfide solid electrolyte material comprises a Li element, a P element, an S element, and an I element, and the cathode active material layer contains a specific phosphate ester.
Schematic cross-sectional view illustrating an example of a solid-state lithium battery.
The figure above is the Toyota patent’s cross-sectional view of a solid-state lithium battery that consists of:
1. Cathode active material layer.
2. Anode active material layer.
3. Solid electrolyte layer.
4. Cathode current collector of the cathode active material layer.
5. Anode current collector of the anode active material layer.
6. Battery case that accommodates these members.
The cathode active material layer (1) contains an oxide active material as a cathode active material. Also, at least one of the cathode active material layer (1) and the solid electrolyte layer (3) contains a sulfide solid electrolyte material. Further, this sulfide solid electrolyte material is usually in contact with the oxide active material contained in the cathode active material layer (1). This sulfide solid electrolyte material comprises a Li element, a P element, an S element and an I element. The cathode active material layer (1) contains a phosphate ester.
Also in Japan, Toshiba announced the development of its next-generation SCiB battery that uses a new material to double the capacity of its anode. The new battery offers high-energy density and the ultra-rapid recharging required for automotive applications, and will give a compact EV with a drive range of 320km after only six minutes of ultra-rapid recharging three times the distance possible with current lithium-ion batteries. That’s for a compact EV with a 32kWh next generation SciB with a JC08 test cycle. Toshiba aims to commercialize the next-generation SciB in fiscal year 2019. Figure 3 compares Toshiba’s EV drive range with various battery charge times.
Toshiba launched the SCiB as a safe, long-life, fast-charging lithium-ion battery in 2008. Since then, the company has constantly refined the technology and improved real-world performance. For its next-generation SCiB, Toshiba has developed a titanium niobium oxide anode material that has double the lithium storage capacity by volume of the graphite-based anodes generally used in lithium-ion batteries.
The new battery also offers high energy density and ultra-rapid recharging characteristics, and its titanium niobium oxide anode is much less likely to experience lithium metal deposition during ultra-rapid recharging or recharging in cold conditions—a cause of battery degradation and internal short circuiting.
Toshiba’s current SCiB employs a lithium titanium oxide anode, and is known for excellent operating characteristics in respect of safety, long life, and rapid charging. It has found wide use in vehicles and industrial and infrastructure applications, including automobiles, buses, railroad cars, elevators, and power plants. The high energy density of the battery and its rapid recharging have made important contributions to enhancing the convenience and promoting the spread of EVs.
Toshiba has developed a proprietary method for synthesizing and disarranging crystals of titanium niobium oxide and storing lithium ions more efficiently in the crystal structure. The anode of the next-generation SciB produced by this approach has twice the capacity of the anode of current lithium-ion batteries.
“We are very excited by the potential of the new titanium niobium oxide anode and the next-generation SCiB,” says Dr. Osamu Hori, director of corporate research & development center at Toshiba Corp. “Rather than an incremental improvement, this is a game-changing advance that will make a significant difference to the range and performance of EV. We will continue to improve the battery’s performance and aim to put the next-generation SCiB into practical application in fiscal year 2019.”
Rigorous testing of a 50Ah prototype of the new battery has confirmed that it retains the long life cycle, low-temperature operation, excellent safety, and rapid recharging characteristics of the current SCiB. The energy density by volume of battery is twice that of the current SCiB. The next-generation SCiB maintains over 90% of its initial capacity after being put through 5,000 charge/discharge cycles, and ultra-rapid recharging can be done in cold conditions, with temperatures as low as minus 10°C, in only 10 minutes.
Part of the research work on the next-generation SCiB was subsidized by Japan’s New Energy and Industrial Technology Development Organization (NEDO).
EV driving ranges (km) for various charging times of Toshiba’s SCiB battery.
At the initiative of European Commission Vice-President Maroš Šefčovič, in charge of Energy Union, a high-level meeting on Battery development and production in Europe took place recently in Brussels. This meeting regrouped the leading actors from the EU industry and member states to discuss the establishment of a full-value chain of batteries in Europe, importantly including large-scale lithium-ion battery cell production. It was recognized that the large-scale manufacturing of lithium-ion cells with highest possible control of IP is crucial for EU economy and job creation for the future. There was a clear sense of urgency by all parties, which included industrial leaders from automotive OEMs, chemical companies, energy companies, and cell-manufacturing companies.
Leclanché SA, one of the world’s leading energy storage solution companies, welcomed the European Union’s plans to make battery storage central to Europe’s energy infrastructure. Anil Srivastava, CEO of Leclanché, and Pierre Blanc, the company’s CTIO, were among the invited participants at the meeting in Brussels yesterday. With its industrial scale manufacturing site in Germany, and its development centers in Switzerland and Belgium, Leclanché is one of the largest manufacturers of lithium-ion cells in Europe, and has one of the strongest industrial basis.
Leclanché Vice-President Šefčovič said this process that should enable Europe to regain a strong position in the battery industry, which will be key in the ongoing transition to clean mobility and clean energy systems. Lithium-ion cell production is central to the achievement of these goals and Leclanché is one of the very few players in Europe with industrial-scale lithium-ion cell-manufacturing experience.
EU funding will be made available, possibly through IPCEI (Important Projects of Common European Interest), and the group will develop an EU-wide action roadmap over the coming months. Work on this is to start immediately, with industrial participants to take the lead.
Anil Srivastava, CEO of Leclanché, says, “Battery technology is vital to the future security of Europe’s energy supply, and the initiative of Vice-President Šefčovič will help create the right momentum and sends a clear signal as to its importance. Leclanché has been investing heavily over the past few years in building the required industrial foundations to be in a position to play an important role in this ambitious plan, and we are delighted to see such a strong and clear position taken by the European Commission. Leclanché, as one of the oldest battery companies in Europe, and with its strong industrial experience, aims to play a key role in this process, as it continues to build its presence in North America, Asia, and further reinforces its existing European activities.”
A clear conclusion of the meeting was to form work strands in order to prepare a concrete roadmap by February 2018 that could set the path to a strong European-based consortium, in many ways inspired by what was achieved 50 years ago in the aerospace sector.