Imagine mobile phone, which holds a charge for more than a week, and then charges in 15 minutes. Fantastic? But it may become a reality thanks to a new study by scientists at Northwestern University (Evanston, Illinois, USA). A team of engineers developed an electrode for lithium-ion rechargeable batteries (which are used in most cell phones today) that increased their energy capacity by 10 times. This pleasant surprises not limited - new battery devices can charge 10 times faster than current ones.
To overcome the restrictions imposed existing technologies on the energy capacity and charge rate of the battery, the scientists applied two different chemical engineering approaches. The resulting battery will not only extend the life of small electronic devices(like phones and laptops), but also pave the way for the development of more efficient and smaller batteries for electric vehicles.
"We have found a way to extend the charge retention time of the new lithium-ion battery by 10 times," said Professor Harold H. Kung, one of the study's lead authors. “Even after 150 charge/discharge sessions, which means at least a year of operation, it remains five times more efficient than lithium-ion batteries on the market today.”
The operation of a lithium-ion battery is based on a chemical reaction in which lithium ions move between an anode and a cathode located at opposite ends of the battery. During battery operation, lithium ions migrate from the anode through the electrolyte to the cathode. When charging, their direction is replaced by the exact opposite. Existing on this moment Batteries have two important limitations. Their energy capacity - that is, the battery's charge retention time - is limited by the charge density, or how many lithium ions can fit on the anode or cathode. At the same time, the charging rate of such a battery is limited by the speed at which lithium ions are able to move through the electrolyte to the anode.
In today's rechargeable batteries, an anode made from many graphene sheets can have only one lithium atom for every six carbon atoms (which make up graphene). In an attempt to increase the energy capacity of batteries, scientists have already experimented with replacing carbon with silicon, which can hold much more lithium: four lithium atoms for every silicon atom. However, silicon during the charging process expands and contracts sharply, which causes fragmentation of the anode substance and, as a result, a rapid loss of the battery charging capacity.
Currently low speed charging the battery is explained by the shape of the graphene sheets: compared to the thickness (which is only one atom), their length is prohibitive. During charging, the lithium ion must cover the distance to the outer edges of the graphene sheets, and then pass between them and stop somewhere inside. Since lithium takes a long time to reach the middle of the graphene sheet, something like an ion jam is observed near its edges.
As already mentioned, Kung's research group solved both of these problems by adopting two different technologies. First, in order to ensure the stability of the silicon and, accordingly, maintain the maximum charging capacity of the battery, they placed silicon clusters between graphene sheets. This made it possible to increase the number of lithium ions in the electrode, while simultaneously using the flexibility of graphene sheets to account for changes in silicon volume during battery charging/discharging.
“Now we kill both birds with one stone,” Kung says. “Thanks to silicon, we get a higher energy density, and the interleaving of layers reduces the power loss caused by the expansion with contraction of silicon. Even with the destruction of silicon clusters, the silicon itself is not going anywhere.”
In addition, the researchers used a chemical oxidation process to create miniature (10-20 nanometers) holes in graphene sheets (“in-plane defects”) that provide lithium ions with “quick access” to the inside of the anode and subsequent storage in it as a result of reaction with silicon. This reduced the time required to charge the battery by a factor of 10.
So far, all efforts to optimize the operation of batteries have been directed to one of their components - the anode. At the next stage of research, scientists plan to study changes in the cathode for the same purpose. In addition, they want to refine the electrolyte system so that the battery can automatically (and reversibly) turn off when high temperatures- a similar protective mechanism could be useful when using batteries in electric vehicles.
According to the developers, current form the new technology should enter the market within the next three to five years. An article on the results of research and development of new batteries was published in the journal Advanced Energy Materials.
And today we will talk about imaginary ones - with a gigantic specific capacity and instant charging. News about such developments appear with enviable regularity, but the future has not yet arrived, and we are still using lithium-ion batteries that appeared at the beginning of the decade before last, or their slightly more advanced lithium-polymer counterparts. So what is the matter, technological difficulties, misinterpretation of the words of scientists, or something else? Let's try to figure it out.
In pursuit of charging speed
One of the battery parameters that scientists and large companies constantly trying to improve - charging speed. However, it will not be possible to increase it indefinitely, not even due to the chemical laws of reactions occurring in batteries (especially since the developers of aluminum-ion batteries have already stated that this type of battery can be fully charged in just a second), but because of physical limitations. Suppose we have a smartphone with a 3000 mAh battery and support fast charging. You can fully charge such a gadget within an hour with a current strength of 3 A on average (on average, because the voltage changes during charging). However, if we want to get a full charge in just one minute, we need a current of 180 A without taking into account various losses. To charge the device with such a current, you need a wire with a diameter of about 9 mm - twice as thick as the smartphone itself. Yes, and a current of 180 A at a voltage of about 5 V is normal Charger will not be able to give out: smartphone owners will need a pulse current converter like the one shown in the photo below.
An alternative to increasing current is increasing voltage. But it is usually fixed, and for lithium-ion batteries it is 3.7 V. Of course, it can be exceeded - charging using Quick Charge 3.0 technology comes with a voltage of up to 20 V, but trying to charge a battery with a voltage of about 220 V is useless will not lead to good, and solve this problem in soon does not seem possible. Modern batteries simply cannot use this voltage.
Perpetual batteries
Of course, we are not talking about perpetual motion machine”, but about batteries with long term services. Modern lithium-ion batteries for smartphones can withstand a maximum of a couple of years of active use of devices, after which their capacity steadily decreases. Owners of smartphones with removable batteries are a little more fortunate than others, but even in this case it is worth making sure that the battery was recently produced: lithium-ion batteries degrade even when not in use.
Scientists at Stanford University proposed their solution to this problem: to cover the electrodes existing types lithium-ion batteries polymer material with the addition of graphite nanoparticles. As conceived by scientists, this will protect the electrodes, which are inevitably covered with microcracks during operation, and the same microcracks in the polymer material will heal on their own. The principle of operation of such a material is similar to the technology used in the LG G Flex smartphone with a self-healing back cover.
Transition to the third dimension
In 2013, there was a report that researchers at the University of Illinois were developing a new type of lithium-ion battery. Scientists have stated that the specific power of such batteries will be up to 1000 mW / (cm * mm), while the specific power of conventional lithium-ion batteries ranges between 10-100 mW / (cm * mm). These units of measurement were used, since we are talking about rather small structures with a thickness of tens of nanometers.
Instead of the flat anode and cathode used in traditional Li-Ion batteries, the scientists proposed using bulk structures: a nickel sulfide crystal lattice on porous nickel as the anode and lithium manganese dioxide on porous nickel as the cathode.
Despite all the doubts caused by the absence in the first press releases exact parameters new batteries, as well as prototypes not presented so far, new type battery is still real. This is confirmed by several scientific articles on this topic published over the past two years. However, if such batteries become available to end users, this will not happen very soon.
Charging through the screen
Scientists and engineers are trying to extend the life of our gadgets not only by searching for new types of batteries or increasing their energy efficiency, but also quite in unusual ways. Michigan State University researchers have proposed embedding transparent solar panels directly into the screen. Since the principle of operation of such panels is based on the absorption of solar radiation by them, in order to make them transparent, scientists had to resort to a trick: the material of the new type of panels absorbs only invisible radiation (infrared and ultraviolet), after which photons, reflected from the wide edges of the glass, are absorbed by narrow strips solar panels of the traditional type located at its edges.
The main obstacle to the introduction of such technology is the low efficiency of such panels - only 1% versus 25% of traditional solar panels. Now scientists are looking for ways to increase the efficiency to at least 5%, but a quick solution to this problem can hardly be expected. By the way, a similar technology was recently patented by Apple, but it is not yet known exactly where the manufacturer will place solar panels in their devices.
Before that, by the words “battery” and “accumulator”, we meant a rechargeable battery, but some researchers believe that it is quite possible to use disposable voltage sources in gadgets. As batteries that could work without recharging or other maintenance for several years (or even several decades), scientists at the University of Missouri proposed using RITEGs - radioisotope thermoelectric generators. The principle of RTG operation is based on the conversion of heat released during radio decay into electricity. Many such installations are known for their use in space and hard-to-reach places on Earth, but in the US miniature radioisotope batteries have also been used in pacemakers.
Work on an improved type of such batteries has been underway since 2009, and prototypes of such batteries have even been shown. But we will not be able to see radioisotope batteries in smartphones in the near future: they are expensive to manufacture, and, moreover, many countries have strict restrictions on the production and circulation of radioactive materials.
Can also be used as disposable batteries hydrogen elements, but they cannot be used in smartphones. Hydrogen batteries run out pretty quickly: although your gadget will last longer on one cartridge than on a single charge of a conventional battery, they will have to be changed periodically. However, this does not prevent the use of hydrogen batteries in electric vehicles and even external batteries: while these are not mass devices, but they are no longer prototypes. Yes, and Apple is rumored to be already developing a system for refilling hydrogen cartridges without replacing them for use in future iPhones.
The idea that a battery with a high specific capacity can be created on the basis of graphene was put forward back in 2012. And so, at the beginning of this year, Spain announced the start of construction by Graphenano of a plant for the production of graphene-polymer batteries for electric vehicles. The new type of battery is almost four times cheaper to produce than traditional lithium polymer batteries, has a specific capacity of 600 Wh/kg, and can be charged to 50 kWh in just 8 minutes. True, as we said at the very beginning, this will require a power of about 1 MW, so this figure is achievable only in theory. When exactly the plant will start producing the first graphene-polymer batteries is not reported, but it is quite possible that Volkswagen will be among the buyers of its products. The concern has already announced plans to produce electric vehicles with a range of up to 700 kilometers from a single battery charge by 2018.
Concerning mobile devices, while the use of graphene-polymer batteries in them is hindered large dimensions such batteries. Let's hope that research in this area will continue, because graphene-polymer batteries are one of the most promising types of batteries that may appear in the coming years.
So why, despite all the optimism of scientists and the regularly appearing news about breakthroughs in the field of energy conservation, are we now seeing stagnation? First of all, the matter is in our high expectations, which are only fueled by journalists. We want to believe that a revolution in the world of batteries is about to take place, and we will get a battery with a charge in less than a minute, and with an almost unlimited life, which will last at least a week on a modern smartphone with an octa-core processor. But such breakthroughs, alas, do not happen. I put into mass production any new technology many years before scientific research, sample testing, development of new materials and technological processes and other work that takes a lot of time. In the end, the same lithium-ion batteries took about five years to turn from engineering samples into finished devices that can be used on phones.
Therefore, we can only stock up on patience and not take the news about new batteries to heart. At least until there is news of their mass production launch, when there is no doubt about the viability of the new technology.
Batteries are an all-or-nothing rule. Without next-generation energy storage, there will be no turning point in energy policy, nor in the electric vehicle market.
Moore's law, postulated in the IT industry, promises an increase in processor performance every two years. The development of batteries is lagging behind: their efficiency is increasing by an average of 7% per year. And while lithium-ion batteries in modern smartphones last longer and longer, this is largely due to the optimized performance of the chips.
Lithium-ion batteries dominate the market due to their light weight and high energy density.
Every year, billions of batteries are installed in mobile devices, electric vehicles and renewable energy storage systems. However modern technology has reached its limit.
The good news is that the next generation of lithium-ion batteries already almost meets the requirements of the market. They use lithium as a storage material, which theoretically allows a tenfold increase in energy storage density.
Along with this, studies of other materials are given. Although lithium provides an acceptable energy density, however, we are talking about designs that are several orders of magnitude more optimal and cheaper. After all, nature could provide us best schemes for high quality batteries.
University research labs develop first prototypes organic batteries. However, more than one decade may pass before such biobatteries enter the market. A bridge to the future helps stretch small-sized batteries that are charged by capturing energy.
Mobile power supplies
According to Gartner, more than 2 billion mobile devices will be sold this year, each with a lithium-ion battery. These batteries are considered the standard today, in part because they are so lightweight. However, they only have a maximum energy density of 150-200 Wh/kg.
Lithium-ion batteries charge and release energy by moving lithium ions. When charging, positively charged ions move from the cathode through the electrolyte solution between the graphite layers of the anode, accumulate there and attach the charging current electrons.
When discharging, they give off electrons to the current circuit, lithium ions move back to the cathode, in which they again bind to the metal (in most cases, cobalt) and oxygen located in it.
The capacity of lithium-ion batteries depends on how many lithium ions can be located between the layers of graphite. However, thanks to silicon, today you can achieve more effective work batteries.
In comparison, it takes six carbon atoms to bind one lithium ion. One silicon atom, on the other hand, can hold four lithium ions.
A lithium-ion battery stores its electricity in lithium. When the anode is charged, lithium atoms are stored between the layers of graphite. When discharging, they donate electrons and move in the form of lithium ions into the layered structure of the cathode (lithium cobaltite).
Silicon increases capacitance
The capacity of batteries increases when silicon is included between graphite layers. It increases three to four times when silicon is combined with lithium, but after several charging cycles, the graphite layer breaks.
The solution to this problem is found in startup project Amprius created by scientists from Stanford University. The Amprius project received support from people such as Eric Schmidt (Chairman of the Board of Directors of Google) and Nobel laureate Steven Chu (until 2013 - US Secretary of Energy).
Porous silicon in the anode increases the efficiency of lithium-ion batteries by up to 50%. During the implementation of the Amprius startup project, the first silicon batteries were produced. Within this project, three methods are available to solve the "graphite problem". The first one is application of porous silicon, which can be thought of as a "sponge". When lithium is stored, it increases very little in volume, therefore, the graphite layers remain intact. Amprius can create batteries that store up to 50% more energy than conventional batteries.
More efficient than porous silicon at storing energy layer of silicon nanotubes. In the prototypes, an almost twofold increase in charging capacity was achieved (up to 350 Wh/kg).
The "sponge" and tubes must still be covered with graphite, as silicon reacts with the electrolyte solution and thus reduces battery life.
But there is also a third method. Ampirus project researchers injected into a carbon shell groups of silicon particles, which are not directly in contact, but provide free space for particles to increase in volume. Lithium can accumulate on these particles, and the shell remains intact. Even after a thousand charge cycles, the capacity of the prototype was reduced by only 3%.
Silicon combines with several lithium atoms, but expands in the process. To prevent the destruction of graphite, the researchers use the structure of the pomegranate plant: they introduce silicon into graphite shells, which are large enough to additionally attach lithium. Many believe that the future of the automotive industry lies with electric cars. Abroad, there are bills according to which part of the cars sold annually must either be hybrids or run on electricity, so money is invested not only in advertising such cars, but also in the construction of gas stations.
However, many people are still waiting for electric cars to become real rivals. traditional cars. Or maybe it will be when the charging time decreases, and the time battery life increase? Perhaps graphene batteries will help humanity in this.
What is graphene?
A revolutionary next-generation material, the lightest and strongest, the most electrically conductive - it's all about graphene, which is nothing more than a two-dimensional carbon lattice one atom thick. The creators of graphene, Konstantin Novoselov, received the Nobel Prize. Usually between opening and start practical use This discovery in practice takes a long time, sometimes even decades, but graphene did not suffer such a fate. Perhaps this is due to the fact that Novoselov and Geim did not conceal the technology of its production.
They not only told the whole world about it, but also showed it: there is a video on YouTube where Konstantin Novoselov talks in detail about this technology. Therefore, perhaps soon we will even be able to make graphene batteries with our own hands.
Developments
Attempts to use graphene were in almost all areas of science. It was tried in solar panels, headphones, housings, and even tried to treat cancer. However, at the moment, one of the most promising and necessary things for mankind is a graphene battery. Recall that with such an indisputable advantage as cheap and environmentally friendly fuel, electric vehicles have a serious drawback - a relatively small top speed and a power reserve of not more than three hundred kilometers.
Solving the problem of the century
A graphene battery works on the same principle as lead batteries with an alkaline or acidic electrolyte. This principle is the electrochemical reaction. By design, a graphene battery is similar to a lithium-ion battery with a solid electrolyte, in which the cathode is coal coke, which is close in composition to pure carbon.
However, there are already two fundamentally different directions among engineers developing graphene batteries. In the United States, scientists have proposed making the cathode from graphene and silicon plates interleaved with each other, and the anode from classical lithium cobalt. Russian engineers have found another solution. Toxic and expensive lithium salt can be replaced with more environmentally friendly and cheap magnesium oxide. The battery capacity is increased in any case by increasing the rate of passage of ions from one electrode to another. This is due to the fact that graphene has high rate electrical permeability and the ability to accumulate an electric charge.
The opinions of scientists regarding innovations are divided: Russian engineers claim that graphene batteries have a capacity twice as large as lithium-ion ones, but their foreign colleagues claim that it is ten times larger.
Graphene batteries were put into mass production in 2015. For example, the Spanish company Graphenano is engaged in this. According to the manufacturer, the use of these batteries in electric vehicles at logistics sites shows the real practical possibilities of a battery with a graphene cathode. For full charge it only takes eight minutes. Maximum length mileage is also able to increase graphene batteries. Charging for 1000 km instead of three hundred - that's what Graphenano Corporation wants to offer the consumer.
Spain and China
Collaborates with Graphenano Chinese company Chint, which bought a 10% stake in the Spanish corporation for 18 million euros. The joint funds will be used to build a plant with twenty production lines. The project has already received about 30 million investments, which will be invested in the installation of equipment and hiring of employees. According to the original plan, the plant was supposed to start producing about 80 million batteries. At the initial stage, China should become the main market, and then it was planned to start deliveries to other countries.
In the second phase, Chint is ready to invest 350 million euros to build another plant with about 5,000 employees. Such figures are not surprising, given that the total income will be about three billion euros. In addition, China, known for its environmental problems, will be provided with environmentally friendly and cheap "fuel". However, as we can see, apart from loud statements, the world did not see anything, only test models. Although Volkswagen Corporation also announced its intention to cooperate with Graphenano.
Expectations and reality
The year is 2017, which means that Graphenano has been engaged in the "mass" production of batteries for two years now, but meeting an electric car on the road is a rarity not only for Russia. All characteristics and data released by the corporation are rather uncertain. In general, they do not go beyond the generally accepted theoretical ideas about what parameters a graphene battery for an electric car should have.
In addition, so far everything that has been presented to both consumers and investors is only computer models, no real prototypes. Adding to the problems is the fact that graphene is a material that is very expensive to manufacture. Despite the loud statements of scientists about how it can be "printed on the knee", at this stage only the cost of some components can be reduced.
Graphene and the global market
Supporters of all sorts of conspiracy theories will say that no one benefits from the appearance of such a car, because then oil will go into the background, which means that revenues from its production will also decrease. However, most likely, the engineers encountered some problems, but do not want to advertise it. The word "graphene" is now on hearing, many consider it therefore, perhaps scientists do not want to spoil its glory.
Problems in development
However, the point may be that the material is really innovative, so the approach requires an appropriate one. Perhaps batteries using graphene should be fundamentally different from traditional lithium-ion or lithium-polymer batteries.
There is another theory. Graphenano Corporation said that new batteries can be charged in just eight minutes. Experts confirm that this is indeed possible, only the power of the power source must be at least one megawatt, which is possible in test conditions at the factory, but not at home. building enough refueling with such a capacity will cost a lot of money, the price of one charge will be quite high, so a graphene battery for a car will not bring any benefit.
Practice shows that revolutionary technologies are integrated into the world market for quite a long time. Many tests must be carried out to ensure the safety of the product, so the release of new technological devices is sometimes delayed for many years.
Consumption ecology. Science and technology: The future of electric vehicles largely depends on the improvement of batteries - they must weigh less, charge faster and at the same time produce more energy.
The future of electric vehicles depends largely on improvements in batteries - they need to weigh less, charge faster and still produce more energy. Scientists have already achieved some results. A team of engineers has created lithium-oxygen batteries that do not waste energy and can last for decades. And an Australian scientist has presented a graphene-based ionistor that can be charged a million times without loss of efficiency.
Lithium-oxygen batteries are lightweight and produce a lot of power and could be ideal components for electric vehicles. But these batteries have significant disadvantage- they wear out quickly and release too much energy as heat for nothing. A new development by scientists from MIT, Argonne National Laboratory and Peking University promises to solve this problem.
Created by a team of engineers, lithium-oxygen batteries use nanoparticles that contain lithium and oxygen. In this case, when the state changes, oxygen is retained inside the particle and does not return to the gas phase. This distinguishes the development from lithium-air batteries, which take oxygen from the air and release it into the atmosphere during the reverse reaction. The new approach makes it possible to reduce the energy loss (value electrical voltage reduced by almost 5 times) and increase battery life.
Lithium-oxygen technology is also well adapted to real-world conditions, unlike lithium-air systems, which deteriorate when exposed to moisture and CO2. In addition, lithium and oxygen batteries are protected from overcharging - as soon as there is too much energy, the battery switches to another type of reaction.
Scientists conducted 120 charge-discharge cycles, while performance decreased by only 2%.
So far, scientists have created only a prototype battery, but within a year they intend to develop a prototype. This does not require expensive materials, and the production is in many ways similar to the production of traditional lithium-ion batteries. If the project is implemented, then in the near future electric vehicles will store twice as much energy for the same weight.
An engineer at Swinburne University of Technology in Australia has solved another problem with batteries - how fast they charge. The ionistor developed by him is charged almost instantly and can be used for many years without loss of efficiency.
Han Lin used graphene, one of the strongest materials to date. Due to its honeycomb-like structure, graphene has a large surface area for energy storage. The scientist 3D-printed graphene sheets, a method of production that also cuts costs and scales up.
The ionistor created by the scientist produces as much energy per kilogram of weight as lithium-ion batteries but charges in a few seconds. At the same time, instead of lithium, it uses graphene, which is much cheaper. According to Han Lin, the ionistor can go through millions of charge cycles without loss of quality.
The battery industry is not standing still. The Kreisel brothers from Austria have created a new type of battery that weighs almost half as much as batteries in Tesla Model S.
Norwegian scientists from the University of Oslo have invented a battery that can be completely. However, their development is intended for urban public transport, which regularly makes stops - at each of them the bus will be recharged and there will be enough energy to get to the next stop.
Scientists at the University of California, Irvine are getting closer to creating a perpetual battery. They have developed a nanowire battery that can be recharged hundreds of thousands of times.
And engineers at Rice University managed to create one that operates at a temperature of 150 degrees Celsius without loss of efficiency. published
