Northwestern University researchers have found a way to make a lithium battery last longer with more capacity and cheaper. The team used iron and oxygen to simultaneously drive the electrochemical reaction.

Experience suggests Christopher Wolverton’s super lithium-rich battery should not work. For one, the novel battery uses iron, an inexpensive metal that has notoriously failed in batteries. And in another difficult feat, the battery leverages oxygen to help drive the chemical reaction, which researchers previously believed would cause the battery to become unstable.

But not only does the battery work, it does so incredibly well.

The lithium iron oxide battery uses both oxygen and iron to store and release electrical energy.  Image Credit: Zhenpeng Yao, Northwestern University.   Click image for the largest view.

Teaming up with researchers at Argonne National Laboratory, Wolverton’s group at Northwestern University developed a rechargeable lithium-iron-oxide battery that can cycle more lithium ions than its common lithium-cobalt-oxide counterpart. The result is a much higher capacity battery that could enable smart phones and battery-powered automobiles to run much longer.

Wolverton, professor of materials science and engineering in Northwestern’s McCormick School of Engineering said, “Our computational prediction of this battery reaction is very exciting, but without experimental confirmation, there would be a lot of skeptics. The fact that it actually works is remarkable.”

Supported by the US Department of Energy’s Energy Frontier Research Center program, the research was recently published in Nature Energy.

Zhenpeng Yao, a PhD student in Wolverton’s laboratory, and Chun Zhan, a postdoctoral fellow at Argonne, served as the paper’s first authors. Wolverton and Yao led the computational development, and Argonne led the experimental component of the research.

Lithium-ion batteries work by shuttling lithium ions back and forth between the anode and the cathode. When the battery is charged, the ions move back to the anode, where they are stored. The cathode is made from a compound that comprises lithium ions, a transition metal, and oxygen. The transition metal, which is typically cobalt, effectively stores and releases electrical energy when lithium ions move from the anode to the cathode and back. The capacity of the cathode is then limited by the number of electrons in the transition metal that can participate in the reaction.

“In the conventional case, the transition metal is doing the reaction,” Wolverton said. “Because there is only one lithium ion per one cobalt, that limits of how much charge can be stored. What’s worse is that current batteries in your cell phone or laptop typically only use half of the lithium in the cathode.”

Today’s typical lithium-cobalt-oxide battery has been on the market for 20 years, but researchers have long searched for a less expensive, higher capacity replacement. Wolverton’s team has improved upon the common lithium-cobalt-oxide battery by leveraging two strategies: replacing cobalt with iron, and forcing oxygen to participate in the reaction process.

If the oxygen could also store and release electrical energy, the battery would have the higher capacity to store and use more lithium. Although other research groups have attempted this strategy in the past, few have made it work.

“The problem previously was that often, if you tried to get oxygen to participate in the reaction, the compound would become unstable,” Yao said. “Oxygen would be released from the battery, making the reaction irreversible.”

Through computational calculations, Wolverton and Yao discovered a formulation that works reversibly. First, they replaced cobalt with iron, which is advantageous because it’s among the cheapest elements on the periodic table. Second, by using computation, they discovered the right balance of lithium, iron, and oxygen ions to allow the oxygen and iron to simultaneously drive a reversible reaction without allowing oxygen gas to escape.

“Not only does the battery have an interesting chemistry because we’re getting electrons from both the metal and oxygen, but we’re using iron,” Wolverton said. “That has the potential to make a better battery that is also cheap.”

Perhaps even more importantly, the fully rechargeable battery starts with four lithium ions, instead of one. The current reaction can reversibly exploit one of these lithium ions, significantly increasing the capacity beyond today’s batteries. But the potential to cycle all four back and forth by using both iron and oxygen to drive the reaction is tantalizing.

“Four lithium ions for each metal – that would change everything,” Wolverton said. “That means that your phone could last eight times longer or your car could drive eight times farther. If battery-powered cars can compete with or exceed gasoline-powered cars in terms of range and cost, that will change the world.”

Wolverton has filed a provisional patent for the battery with Northwestern’s Innovation and New Ventures Office. Next, he and his team plan to explore other compounds where this strategy could work.

Its a leap forward in lithium chemistry technology. Still, the plan doesn’t go forward to finish off using all four potential sites for lithium ions, so the huge capacity payoff isn’t being addressed.

But this surely will light off the interest of other researchers if the patent rights don’t stand in the way. A lower cost battery with as much as eight times the capacity has to be an immense incentive to manufacturers and consumers.

A research team from the International Institute for Carbon-Neutral Energy Research at Kyushu University has built a flow-type polymer electrolyte cell for power storage, a device to store energy in chemical form through continuous electrolysis.

This already competitive energy-storage device could be used to balance out the fluctuations in renewable power supplies. Storing electricity is not without its challenges. Interest in renewable energy continues to grow, but many renewables can be frustratingly intermittent, when the sun stops shining, or the wind stops blowing, the power stops. The only credible answer is a fluctuating supply that can be partly smoothed-out by energy storage during peak production times.

The new flow-type polymer electrolyte cell reduces oxalic acid (OX) to glycolic acid, which has a higher volumetric energy-storage capacity than hydrogen gas. A newly fabricated TiO2 cathode enhanced the speed and efficiency of OX reduction.

The team has described the device by publication in Scientific Reports.  The paper is open source at this writing.

A Kyushu University research team realized continuous electrochemical synthesis of an alcohol compound from a carboxylic acid using a polymer electrolyte alcohol electrosynthesis cell, which enables direct power charge into alcoholic compound. Image Credit: Masaaki Sadakiyo, International Institute for Carbon-Neutral Energy Research, Kyushu University. Click image for the largest view.

The researchers noted that glycolic acid (GC) has a much greater energy capacity than hydrogen, one of the more popular energy-storage chemicals. GC can be produced by four-electron reduction of oxalic acid (OX), a widely available carboxylic acid. The team devised an electrolytic cell based on a novel membrane-electrode assembly. Sandwiched between two electrodes are an iridium oxide-based anode and a titanium dioxide (TiO2)-coated titanium (Ti) cathode, linked by a polymer membrane.

Study lead author Masaaki Sadakiyo explained, “Flow-type systems are very important for energy storage with liquid-phase reaction. Most electrolyzers producing alcohols operate a batch process, which is not suitable for this purpose. In our device, by using a solid polymer electrolyte in direct contact with the electrodes, we can run the reaction as a continuous flow without addition of impurities (e.g. electrolytes). The OX solution can effectively be thought of as a flowable electron pool.”

Another key consideration is the cathode design. The cathodic reaction is catalyzed by anatase TiO2. To ensure a solid connection between catalyst and cathode, the team “grew” TiO2 directly on Ti in the form of a mesh or felt. Electron microscope images show the TiO2 as a wispy fuzz, clinging to the outside of the Ti rods like a coating of fresh snow. In fact, its job is to catalyze the electro-reduction of OX to GC. Meanwhile, at the anode, water is oxidized to oxygen.

The team found that the reaction accelerated at higher temperatures. However, turning the heat up too high encouraged an unwanted by-process – the conversion of water to hydrogen. The ideal balance between these two effects was at 60°C (156.2º F). At this temperature, the device could be further optimized by slowing the flow of reactants, while increasing the amount of surface area available for the reaction.

Interestingly, even the texture of the fuzzy TiO2 catalyst made a major difference. When TiO2 was prepared as a “felt,” by growing it on thinner and more densely packed Ti rods, the reaction occurred faster than on the “mesh” – probably because of the greater surface area. The felt also discouraged hydrogen production, by blanketing the Ti surface more snugly than the mesh, preventing the exposure of bare Ti.

Co-author Miho Yamauchi said, “In the right conditions, our cell converts nearly 100% of OX, which we find very encouraging. We calculate that the maximum volumetric energy capacity of the GC solution is around 50 times that of hydrogen gas. To be clear, the energy efficiency, as opposed to capacity, still lags behind other technologies. However, this is a promising first step to a new method for storing excess current.”

This is an amazing discovery or invention. However it is described, this new technology is a welcome birth. There doesn’t seem to be any dreadfully expensive ingredients, nor wildly exotic process technologies in construction. It works best at sub fresh made coffee temperatures.

Yes it is the first step, newly born. But the potential here is fantastic, a word seldom used here, so lets hope the innovators, developers and engineers get enthused. Up to 50 times the energy capacity of hydrogen in an unpressurized container of glycolic acid, an ingredient in skin care. Its a tremendous incentive!

Ulsan National Institute of Science and Technology (UNIST) scientists have introduced the highest reported electrochemical performance in hydrogen production. The joint research team’s Hybrid-Solid Electrolysis Cell (Hybrid-SOEC) system has attracted much attention as a new promising option for the cost-effective and highly efficient hydrogen production as it shows excellent performance compared with other water-electrolysis systems.

The breakthrough has been led by Professor Guntae Kim in the School of Energy and Chemical Engineering at UNIST in collaboration with Professor Tak-Hyoung Lim of Korea Institute of Energy Research (KIER) and Professor Jeeyoung Shin of Sookmyung Women’s University.

The team’s study paper has been published in the journal Nano Energy.

Hybrid-Solid Electrolysis Cell Process Graphic. Image Credit: UNIST. Click image for the largest view.

A solid oxide electrolyzer cell (SOEC) consists of two electrodes and an electrolyte that are all in a solid-state. These are strongly desired as new candidates for hydrogen production because they require no need to replenish lost electrolytes and eliminate the corrosion problems. Additionally the SOECs also operate at relatively high temperatures (700-1000 °C), which helps to offer reduced electrical energy consumption.

Professor Kim and his research team have been seeking ways to improve energy efficiency of hydrogen production, using a SOEC. In the study, the research team has demonstrated the novel concept of Hybrid-SOEC based on the mixed ionic conducting electrolyte, allowing water electrolysis to occur at both the hydrogen and air electrodes.

Existing SOEC electrolytes allow the transport of either only one of the hydrogen or oxygen ions to the other electrode. For the cases like the SOEC electrolytes that transport oxygen ions, water electrolysis occurs at the anode and this results in the production of hydrogen. In contrast, the SOEC electrolytes that transport hydrogen ions cause water electrolysis to occur at the cathode and this results in the production of oxygen. Here, hydrogen travels through the electrolyte to the anode.

Theoretically, using electrolytes that transport both hydrogen and oxygen ions, allows the production of two electrolysis products, hydrogen and oxygen, on both sides of the cell. This could improve the hydrogen production rate greatly. In the study, the research team paid attention to the control of properties of electrolyte.

In this study, Professor Kim and his research team reported their new findings in exploring a SOEC based on a mixed-ion conductor that can transport both oxygen ion and proton at the same time, which is denoted as a ‘Hybrid-SOEC’.

In comparison to other SOECs and representative water-electrolysis devices reported in the literature, the proposed system demands less electricity for hydrogen production, while exhibiting outstanding electrochemical performance with stability. Moreover, the Hybrid SOEC exhibits no observable degradation in performance for more than 60 hours of continuous operation, implying a robust system for hydrogen production.

Junyoung Kim who is in the doctoral program of Energy and Chemical Engineering and the first author of the study said, “By controlling the driving environment of the hydrogen ion conductive electrolyte, a ‘mixed ion conductive electrolyte’ in which two ions pass can be realized. In a Hybrid-SOEC where this electrolyte was first introduced, water electrolysis occurred at both electrodes, which results in significant increase in total hydrogen production.”

A layered perovskite with excellent electrochemical properties was used as the electrode of the Hybrid-SOEC. By adding an excellent electrode material on mixed ionic conducting electrolyte resulted in enhanced electrochemical performance. As a result, the corresponding yields of hydrogen produced were 1.9 L per hour at a cell voltage of 1.5 V at 700 °C. This is four times higher hydrogen production efficiency than the existing high-efficient water electrolytic cells.

A four fold increase in production is a very impressive result. That gain might be enough to compensate for the energy used to get the process system and water input up to an operating temperature of over 700º C.

The hydrogen production race is still on, but this is a breakout breakthrough that really raises the stakes.

An Osaka University research team has created a thermoelectric material with promising performance at room temperature. The non-toxic, room-temperature thermoelectric material is competitive with conventional bismuth telluride, and could be used for power generation or refrigeration.

Thermoelectric (TE) materials could play a key role in future technologies. Although the applications of these remarkable compounds have long been explored, they are mostly limited to high-temperature devices.

(a) Three-dimensional crystal structure of YbSi2, (b) view along the a-axis, and (c) along the c-axis. Image Credit: Kurosaki et al, Osaka University. Click image for the largest view.

Using ytterbium silicide because it is a good electrical conductor that also has a high Seebeck coefficient thanks to Kondo resonance (fluctuation of f-electrons) increases its power factor. Its layered structure further promotes the thermoelectric effect by blocking heat conduction.

Their study, published in Physica Status Solidi RRL, could help bring these materials out of the high-temperature niche and into the mainstream.

TE materials display the thermoelectric effect: apply heat on one side, and an electric current starts to flow. Conversely, run an external current through the device, and a temperature gradient forms; i.e., one side becomes hotter than the other. By interconverting heat and electricity, TE materials can be used as either power generators (given a heat source) or refrigerators (given a power supply).

The ideal TE material combines high electrical conductivity, allowing the current to flow, with low thermal conductivity, which prevents the temperature gradient from evening out. The power generation performance mainly depends on the “power factor,” which is proportional to both electrical conductivity and a term called the Seebeck coefficient.

Study co-author Sora-at Tanusilp explained, “Unfortunately, most TE materials are often based on rare or toxic elements. To address this, we combined silicon – which is common in TE materials – with ytterbium, to create ytterbium silicide [YbSi2]. We chose ytterbium over other metals for several reasons. First, its compounds are good electrical conductors. Second, YbSi2 is non-toxic. Moreover, this compound has a specific property called valence fluctuation that make it a good TE material at low temperatures.”

The first advantage of YbSi2 is that the Yb atoms occupy a mixture of valence states, both +2 and +3. This fluctuation, also known as Kondo resonance, increases the Seebeck coefficient with keeping metal-like high electrical conductivity at low temperature, and therefore the power factor.

Second, YbSi2 has an unusual layered structure. While the Yb atoms occupy crystal planes similar to pure Yb metal, the Si atoms form hexagonal sheets between those planes, resembling the carbon sheets in graphite. This blocks the conduction of heat through the material, and therefore keeps the thermal conductivity down, preserving the temperature gradient. The researchers believe that heat conduction is further suppressed by controlling the structure in nanoscale and traces of impurities and other defects.

The result is an encouragingly high power factor of 2.2 mWm-1K-2 at room temperature. This is competitive with conventional TE materials based on bismuth telluride. As corresponding author of this study Ken Kurosaki explains, “The use of Yb shows we can reconcile the conflicting needs of TE materials through carefully selecting the right metals. Room-temperature TEs, with moderate power, can be seen as complementary to the conventional high-temperature, high-power devices. This could help unlock the benefits of TE in everyday technology.”

This is exceptionally interesting news. Thermoelectric devices could be the first real big step into salvaging energy lost as heat and returning the energy back for use. Heat loss is by far the single most energy wasting event in using energy. Working at room temperatures is huge improvement and gets the potential into the range of real markets. Congratulations are in order, lets hope this technology can scale up!

Argonne National Laboratory scientists have recently used a new and counterintuitive approach to create a better catalyst. The new catalyst has been made to support one of the reactions involved in splitting water into hydrogen and oxygen.

By first creating an alloy of two of the densest naturally occurring elements and then removing one, the scientists reshaped the remaining material’s structure so that it better balanced three important factors: activity, stability and conductivity.

In the new study, researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, Johns Hopkins University, Drexel University and several universities in South Korea used a new and counterintuitive approach to create a better catalyst that supports one of the reactions involved in splitting water into hydrogen and oxygen. The study has been published in Nature Communications. The scientists plan to use the generated hydrogen as a clean fuel.

By first creating an alloy of two of the densest naturally occurring elements and then removing one, the scientists reshaped the remaining material’s structure so that it better balanced three factors important for chemical reactions: activity, stability and conductivity.

Representative SEM images of dealloyed Ir x Os(1−x) catalysts revealing a porous architecture, with varying pore size (10–100 nm) and surface-to-volume ratio generated through the dealloying process. Image Credit: Argonne National Laboratory. Click image for the largest view.

Nenad Markovic, an Argonne materials scientist and author of the study said, “Finding a material that works well for energy conversion or storage is like creating a happy marriage. In our case, we found that a dynamic partnership between two different materials helped us integrate competing concerns.”

Scientists searching for new catalysts have scoured the periodic table to find the right elements or combinations of elements to maximize a catalyst’s activity in water-splitting reactions, as well as the durability of the active sites on its surface. Finding materials that are both stable and active, however, has been a challenge.

Markovic explained, “More active catalysts tend to be less stable. Those that seem to work twice as well usually work only half as long. It is becoming obvious that designing active catalysts is not enough – we need to have not only active, but also stable, materials.”

For the new catalyst, Markovic and his colleagues turned to iridium, a metal most commonly associated with meteorites. As a thin film, iridium is catalytically active, but as it reacts over time with an electrolyte environment, iridium atoms become oxidized. During this process, some of them leave the catalyst’s surface through corrosion, increasingly impairing its performance.

The research team worked to prevent the oxidation by reorganizing the iridium’s structure. To help stabilize and activate iridium, they alloyed it with its neighbor on the periodic table, osmium.

Unlike iridium, osmium is neither catalytically active nor stable, but it did offer a key benefit. After alloying the osmium and iridium together, the researchers then de-alloyed the two metals, leaving behind only a reconfigured structure of three-dimensional iridium nanopores.

“Without the osmium, the iridium would never achieve this state,” Markovic said. “We needed to introduce and then remove the osmium to get a form of iridium that was both active and stable.”

Markovic said each nanopore’s enhanced catalytic stability is due to the small volume of electrolyte within a pore becoming quickly saturated with iridium ions so that surface atoms stop dissolving, in much the same way that it is easier to saturate a teacup of water with sugar than a 10-gallon jug.

While the nanopore’s structure addressed the need for a stable, active catalyst, it was another facet of the iridium’s reconfiguration that helped boost the material’s electron conductivity. Under operational conditions, the porous catalyst actually forms a unique shell of less-conductive iridium oxide around its highly conductive iridium metal interior. This way, electrons can move easily through most of the catalyst to reach the surface, where the water molecule waits on electrons to initiate the water-splitting reaction.

“Essentially, we’re trying to find a way to send electrons through on the ‘expressway,’ rather than making them take the side roads,” Markovic explained. “This core-shell configuration [of the nanoporous material] allows us to do that.”

The progress keeps on coming for producing hydrogen from water. Now if the electrical production could get aligned to produce the power in a non resource consuming way and storing hydrogen wouldn’t be such a daunting task, the hydrogen economy might get a foothold. It still looks like a very long wait.


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