According to Wired magazine, lithium-ion batteries are powering a wide range of electronic products, from smart phones to laptops, from electric cars to e-cigarettes. However, as the potential of lithium is being developed to the extreme, researchers are working Try to find the next battery breakthrough. If you read this article on your smartphone, it means you are holding a 'bomb'. Under the protective screen, lithium (a very volatile metal, once with water) Compounds that are ignited by contact are being broken down and reconstituted in a powerful chemical reaction that provides an indispensable driving force for the modern world.
Lithium is being used in mobile phones, tablets, laptops and smart watches, and is found in our e-cigarettes and electric vehicles. It is light and soft, and is energy-intensive, making it a portable electronic product. The source of perfect power. However, as consumer technology becomes more powerful, lithium-ion battery technology has always been difficult to keep up with. Now, just as the world is addicted to lithium, scientists are vying to reinvent The world's powered battery.
Huge illuminated screens, faster processing speeds, fast data connections, and slim design are all that make it difficult for many smartphones to support the entire day. Sometimes, mobile users even have to charge multiple times. After two years of use, the battery life of many devices will be sharply shortened and have to be thrown into the garbage. The huge advantage of lithium is also its biggest weakness. It is unstable and may explode. The energy of lithium-ion laptop battery It's almost the same as a hand grenade. Mike Zimmerman, founder and CEO of Ionic Materials, said: 'There is a smartphone in the pocket like a kerosene in your pocket.'
Zimmerman witnessed the burning effect at his company research laboratory in Woburn, Massachusetts, USA. In one experiment, a machine drives a nail through a battery pack, and the battery pack expands rapidly. Like popcorn in a microwave oven, it glows brightly. The battery research of the past 50 years has always been a tightrope between performance and safety, that is, extruding as much energy as possible without pushing lithium to extremes.
We are doing this now. It is predicted that by 2022, the global battery market will reach 25 billion US dollars. But consumers believe that in one survey after another, battery life is the most concerned about smartphones. Function. With the popularity of 5G networks with higher energy consumption in the next decade, the problem will only get worse and worse. For those who can solve the problem, they will get huge returns.
Ionic Materials is just one of dozens of companies that are embarking on an epic competition that fundamentally rethinks the battery problem. However, the competition has been plagued by wrong beginnings, painful litigation and failed startups. After ten years of slow development, hope is still there. Scientists from start-ups, universities and well-funded national laboratories around the world are using sophisticated tools to find new materials. They seem to be about to dramatically increase the energy density of smartphone batteries. And battery life, and create more environmentally friendly, safer devices that will be recharged in seconds and are sufficient for continuous use throughout the day.
The battery generates electricity by decomposing chemicals. Since the Italian physicist Alessandro Volta invented the battery in 1799 to solve the frog debate, each battery has the same key components. : Two metal electrodes - a negatively charged anode and a positively charged cathode, separated by a substance called an electrolyte. When the battery is connected to an electrical circuit, the metal atoms in the anode react chemically. They lose an electron. Becomes a positively charged ion and is attracted to the positive electrode through the electrolyte. At the same time, electrons (also negatively charged) flow to the cathode. But it does not pass through the electrolyte, but propagates through the circuit outside the cell. It is connected to the device to supply power.
The metal atoms on the anode will eventually run out, which means the battery is running out of power. But in rechargeable batteries, this process can be reversed by charging, forcing the ions and electrons back to their original position, ready to start the cycle again. Brigade. Electrodes made of pure metal cannot withstand the constant pressure of atoms to enter and exit without collapsing, so rechargeable batteries must use a combination of materials to keep the anode and cathode in shape through repeated charging cycles. This structure can be compared to apartment buildings. There are 'rooms' for reactive elements. The performance of rechargeable batteries depends to a large extent on how fast you can get in and out of these rooms without causing the building to collapse.
In 1977, young British scientist Stan Whittingham worked at the Exxon plant in Linden, New Jersey. He built an anode and used aluminum to form an 'apartment block. Walls and floors', using lithium as the active material. When he charges the battery, lithium ions move from the cathode to the anode and precipitate in the gap between the aluminum atoms. When discharging, they move in the other direction, back through the electrolyte. Space to the side of the cathode.
Whittingham invented the world's first rechargeable lithium battery, a coin-sized battery that powers a solar watch. But when he tries to increase the voltage (making more ions in and out) or trying to make a bigger battery At the time, they will continue to burn. In 1980, the American physicist John Goodenough, who worked at Oxford University, made a breakthrough. Goodnow was a Christian, once in the second world. In the war, he served as a US Army meteorologist. He is also an expert in metal oxides. He suspects that there is definitely a substance that can provide a stronger cage for lithium than the aluminum compound used by Whitingham.
Goodnow guided two postdoctoral researchers to systematically explore the periodic table, comparing lithium with different metal oxides to see how much lithium could be extracted from them before they collapsed. Finally, they identified lithium. a mixture of cobalt and blue, which is a blue-gray metal throughout central Africa. Lithium cobalt oxide can withstand the limit of half of lithium being pulled out. When it is used as a cathode, this represents a big step forward in battery technology. Step. Cobalt is a lighter, less expensive material that is suitable for both small and large equipment and is superior to other materials on the market.
Today, Goodnow's cathode appears almost on all the handheld devices on Earth, but he has not made a penny from it. Oxford refused to apply for a patent, and he himself gave up this right. But it changed the possibility. What happened. In 1991, after 10 years of tinkering, Sony combined Goodnow's lithium cobalt oxide cathode with a carbon anode to try to improve the battery life of its new CCD-TR1 camera. This is the first. A rechargeable lithium-ion battery for consumer products that has changed the world.
Gene Berdichevsky was the seventh employee of Tesla. When the electric car company was founded in 2003, the battery energy density has steadily increased for ten years, and the annual increase The range was about 7%. But by around 2005, Berdychevsky found that the performance of lithium-ion batteries began to stabilize. In the past seven or eight years, scientists have to do their best to fight for even 0.5%. Improved battery performance.
The progress at the time was mainly due to improvements in engineering and manufacturing. Berdychevsky said: 'After 27 years of modern chemical reactions, they are constantly undergoing refinement. 'Materials are more pure, battery manufacturers have been able to make each layer The way to get thinner is to load more active materials into the same space. Berdychevski calls it 'sucking air out of the jar'. But it also has its own risks. Modern batteries consist of extremely thin cathodes The alternating layers of electrolyte and anode materials are tightly integrated with the copper and aluminum charge collectors to carry the electrons out of the battery and to the desired location.
In many high-end batteries, a plastic diaphragm is placed between the cathode and the anode to prevent contact and short-circuit, and is only 6 microns thick (about 1/10 of the thickness of a human hair), which makes them susceptible to crush damage. This is why the airline's security video now warns that if your phone falls into the mechanism, don't try to adjust the seat.
Every improvement in lithium-ion batteries requires trade-offs. Increasing energy density reduces safety. Introducing fast charging may reduce the cycle life of the battery, which means that the performance of the battery drops even faster. The potential of lithium ions is approaching its Theoretical limits. Since Goodnow's breakthrough, researchers have been trying to find the next leap, including systematically examining the four main components of the battery – the cathode, the anode, the electrolyte and the separator – and using it. The more complicated the tool.
Clare Grey is a student of Goodnow at Oxford University. He has been studying lithium-air batteries, using oxygen in the air as another electrode. In theory, these batteries provide enormous energy. Density, but let them charge reliably, and last for more than a few cycles, is difficult enough in the lab, not to mention the dirty and unpredictable air in the real world.
Although Gray claims to have made a breakthrough recently, due to the above issues, the research community's attention has shifted to lithium-sulfur batteries. It provides a cheaper and more powerful alternative to lithium ions, but scientists are always trying to stop it. The cathodes formed on the cathode and the sulfur on the anode dissolve due to repeated charging. Sony claims to have solved this problem and hopes to bring consumer electronics containing lithium-sulfur batteries to the market by 2020. .
At the University of Manchester, material scientist Xuqing Liu is one of those trying to squeeze more energy out of a carbon anode. He combines two-dimensional materials similar to graphene to enlarge the surface area and increase the lithium atom. The number. Liu Xuqing compares it to the number of pages added to a book. The university also invested in the construction of a dry laboratory, which will enable researchers to safely and easily exchange different components to test different electrodes and electrolytes. The combination.
Incredibly, even Goodnow himself is studying this issue. Last year, at the age of 94, he published a paper describing a battery that is three times the capacity of existing lithium-ion batteries. Questioning. A researcher said: 'If anyone other than Goodnow published this article, I might want to marry.'
However, despite the publication of thousands of papers, billions of dollars in funding, and dozens of startups established and funded, the basic chemical functions of most of our consumer electronics products have remained almost unchanged since 1991. In terms of cost, performance and portability of consumer electronics, there is nothing to replace the combination of lithium cobalt oxide and carbon. The iPhone X's battery is almost identical to Sony's first camcorder.
Therefore, in 2008, Berdychevsky left Tesla and began to focus on studying new battery chemistry. He is particularly interested in finding alternatives to graphite anodes, which he believes are the biggest obstacle to making better batteries. Berdychevsky said: 'The use of graphite has been around for six or seven years, and it is now basically used in the thermodynamic capacity of the battery. ' In 2011, he and former colleague Alex of Tesla Alex Jacobs, professor of materials science at Georgia Institute of Technology, Gleb Yushin co-founded Sila Nanotechnologies. They have an open layout in the Bay Area office in Alameda, with Atari games. Named conference room, industrial laboratory filled with furnaces and gas pipes.
After investigating all possible solutions, the three men theoretically determined that silicon is the most promising material. They only need to make the technology work. Many people tried it before, but they all ended in failure. However, Burdy Chevsky and his colleagues are optimistic about their success. A silicon atom can attach 4 lithium ions, which means that a silicon anode can store 10 times more lithium than a graphite anode of similar weight. The potential means that the National Academy of Research is interested in silicon anode materials, as are startups backed by venture capital firms such as Amprius, Enovix and Envia.
When lithium ions adhere to the anode while the battery is charging, it expands slightly and then shrinks again during use. During repeated charge cycles, this expansion and contraction destroys the solid electrolyte interface layer, which is a protection Substance, forming plaque on the surface of the anode. This damage can cause side effects and consume part of the lithium in the battery. Berdychevski said: 'It is trapped in useless rubbish.'
Over time, this is the main reason why smartphones start to lose energy quickly. Graphite anodes expand and contract by about 7%, so it can complete about 1000 charge and discharge cycles before performance begins to fall sharply. This is equivalent to one. The smartphone lasts for two years and is charged every day. But because silicon particles can absorb so much lithium, they swell much more when charging (up to 400%). Most silicon anodes occur after several charge cycles. Break. Over the course of more than five years in the lab, Sila Nanotechnologies created a nanocomposite to solve the expansion problem.
Berdychevski explained that if the graphite anode is an 'apartment', then all the 'rooms' are the same size and are tightly packed together. After 30,000 iterations (different columns and room combinations) ), they form the anode, where each layer has enough space for the silicon atoms to expand when acquiring lithium. He said: 'We trap the extra space inside the building.' This solves the expansion problem while maintaining the anode External dimensions and shape are stable.
Berdychevsky said that the first generation of materials that Sila Nanotechnologies will provide to manufacturers next year will increase energy density by 20% and eventually increase by 40%, while also improving safety. He said: 'Silicon can make You are far from the edge, you can vacate 1% or 2% of the space to really improve your safety. ' Most importantly, it can also be directly converted into an existing design. With Asian battery manufacturers scrambling Increasing plant capacity to prepare for the arrival of the electric vehicle era, Berdychevsky believes that any product that is incompatible with current production processes may be excluded. He said: 'If there is no technology that can replace lithium ions now When it comes to the market, it will usher in countless user groups.'
When the battery is fully charged and discharged, lithium ions dance between the two electrodes, sometimes they are difficult to return. Conversely, especially when the battery is charging too fast, they will accumulate on the outside of the electrode, gradually forming dendritic branches. Like the stalactites at the top of the cave. In the end, these seemingly frosted dendrites on the glazing can extend all the way through the electrolyte, penetrate the diaphragm, and create a short circuit by touching the opposite electrode.
As the distance between the layers gets closer, the risk increases and the chance of error increases. As Samsung discovered last year, mistakes can cause damage and are costly. Tiny manufacturing The defect caused an internal short circuit in the Galaxy Note 7 mobile phone battery. On some devices, the anode and cathode eventually came into contact with each other, and this catastrophic recall event estimated that Samsung lost 3.4 billion euros. Zimmerman of Ionic Materials explained : 'When this happens, the battery will become very hot, and the liquid electrolyte will escape and eventually cause a fire and explosion.'
Because this situation is very dangerous, in fact, there is not so much lithium in lithium-ion batteries, only about two percent. But if there is a way to safely release pure metal lithium from the metal cobalt oxide cage, it is like Whitingham tried to increase the energy density tenfold in the 1970s. This is called the 'Holy Grail' of battery research, and Zimmerman may have discovered it.
He believes that electrolytes are actually the biggest obstacle to increasing the energy density of batteries. People have gradually stopped using substances immersed in liquid electrolytes, but instead use gels and polymers, but they are still generally flammable and prevent rapid The heat escape process did not help. Zimmerman himself admitted that he was not a 'battery control'. He majored in materials science, especially polymers, and he taught at Bell Labs and Tufts University. Years later, I started to start a business.
At the beginning of the 21st century, Zimmerman began to take an interest in rechargeable batteries. At the time, some people were trying to move from liquid electrolytes to solid electrolytes. Senior energy storage scientist Donald Highgate explained: 'In principle, because Solid electrolyte batteries are safer, you can make it work harder. The same application, you can use smaller batteries. 'But they are mostly ceramic or glass products, so they are very brittle and difficult to mass produce.'
Plastics have been used in cells in separators, that is, in the middle of the electrolyte to prevent contact with the electrodes. Zimmerman believes that if he can find the right material, he can discard the liquid electrolyte and separator, and replace it with a Layered solid plastic, this layer of plastic is fire resistant and prevents dendrites from growing between the two layers. With Ionic Materials, Zimmerman created a polymer with a new conduction mechanism that mimics The way electrons pass through the metal. This is the first solid polymer that conducts lithium ions at room temperature. The material is flexible, low cost, and can withstand a variety of tests.
In one experiment, they sent the raw materials to the ballistics lab, where they were usually used to test bulletproof vests and fire them with 9mm bullets. Two wires connected the battery (flat silver bag) to the Samsung tablet. The latter's power supply was carefully removed. After the bullet hit, the battery blasted like a volcano. In the slow motion, plastic and metal could be seen ejected from the crater, like lava. But there was no explosion inside the battery. No explosions or fires. The device stays on every collision. Zimmerman said: 'We always think that polymers make it safer, we never expect the battery to continue working.'
According to Zimmerman, this polymer will drive the development of lithium metal and accelerate the adoption of new battery chemistries such as lithium-sulfur or lithium-air. But the long-term future may not be just lithium. Researcher Liu Xuqing of the University of Manchester Said: 'This improvement can not match the speed of improvement of equipment performance, we need a revolution.'
In the huge Harvard Science and Innovation Park in Oxfordshire, where John Goodenough signed an agreement to abandon his patent for a breakthrough in lithium ion, Stephen Voller A carbon fiber similar in size and shape to the drink cup. Waller is an amiable Manchester City fan, nearly 50 years old. Before joining the first browser brand Netscape, he worked as a software engineer at IBM. After the company was acquired by AOL, Waller was increasingly disappointed with the limitations of laptop battery life, so decided to take some measures.
Waller’s first idea was to use hydrogen fuel cells to extend battery cruising time, but its volatility proved to be a challenge that portable electronics could not overcome. He said: 'It is quite difficult to get hydrogen through airport security.' Then, Through Oxford University acquaintances, Waller has heard about some exciting research, including extremely fast charging materials that behave more like supercapacitors. When batteries store energy chemically, supercapacitors can place them in an electric field. Just like the static collection on a balloon.
The problem with supercapacitors is that they don't store as much energy as a battery, and the charge quickly leaks out. If you don't use it often, lithium-ion batteries can last up to 2 weeks, while supercapacitors can only last for hours. Many in the industry believe that combining supercapacitors with batteries may be beneficial for smartphones and other power-hungry consumer technology products. Highgate says that supercapacitors can be used to make a hybrid that can be fully charged in two minutes. The phone, but also can be used as a spare lithium-ion battery. He said: 'If you can charge very fast, you can put it on the induction coil and charge it when you stir the coffee.'
Waller believes that he can do better. In 2013, he founded ZapGo, which is developing a carbon-based battery that charges as fast as a supercapacitor, but with a charging time similar to that of a lithium-ion battery. By November 2017 The company's employees have grown to 22 people, working at the Appleton Labs in Rutherford and Charlotte, North Carolina. Its first consumer battery will be used at the end of the year. Introduced third-party products, including booster starters for cars, and electric scooters with charging times reduced from 8 hours to 5 minutes.
The carbon fiber that Waller holds in his hand is a battery that uses a solid electrolyte that does not catch fire. The two electrodes are made of thin-layer aluminum covered with nanostructured carbon to increase the surface area. Waller Say: 'You want it to look like the Himalayas.' Despite the microscope, it is more like the outline of the city skyline. The key to ZapGo technology is to improve efficiency and reduce leakage, mainly by ensuring that the electrolyte is seamlessly The carbon skyline above matches, like a Velcro.
The biggest advantage of carbon-based batteries is longevity. Because ZapGo's battery storage is more like a balloon than a traditional battery. As Waller said 'no chemical reaction', he claims that the new battery can last for 100,000 discharge cycles, which is lithium. 100 times more than an ion battery. Even if you charge your phone every day, you can use it for 30 years. The current third-generation ZapGo battery is not yet powerful enough to run a smartphone, but the materials used do not provide an obstacle to increase the voltage, Waller It is expected that this battery will be put into use in 2022, that is, 'iPhone 15 front and rear'.
This requires a change in the charging infrastructure. Many of the explosions were blamed on cheap third-party chargers that don't have the electronics needed to stop the explosion. For ZapGo batteries, or any supercapacitor-based system, you need a charge. To do the opposite thing - pick up and store energy from the grid, and then send it to your phone in a short time. In the lab, Waller's team has built a laptop-sized power supply, but They are working hard to make it smaller and more efficient.
Many people, including Sam Cooper of the Dyson Institute of Design and Engineering, questioned whether these companies really want to implant accessories that last for so long in their products. Cooper said: 'Mobile phone company There is a clear profit incentive, which is to stop the old equipment in time for the next release. For this reason, the competition to develop better batteries may not exist at all. ' Waller acknowledges that one of the 30 patents ZapGo holds The method can artificially reduce the battery life and prevent them from continuing to use for 30 years. He said: 'We will not do this, but if the customer is willing, we have the ability to provide them.'
Compared with the prior art, carbon-based energy storage technology has another major advantage. It can actually be used as an external structure of mobile phones. Waller has not designed a battery suitable for current mobile phone design, but for flexible screens and Preparing for the future of folding equipment. Under the 5G network, all our data comes from the cloud, and battery life becomes more important.
Waller walked along the narrow corridor of his office, walking into the afternoon sun, through the shadow of the Diamond Light Source, a huge ring-shaped building that looked like an alien spaceship landed in the Oxfordshire countryside. Researchers are using accelerated beams to study potential battery materials on a microscopic scale, exploring why lithium-sulfur batteries fail, and finding alternative materials to get anodes and cathodes, which have plagued the field for nearly 30 years.
Waller waved his smartphone in the air, lamenting the flaws in lithium-ion batteries, which prompted him and hundreds of others to join this high-risk race in order to reinvent these flawless but flawed Battery. He said: 'We all have to develop strategies to deal with this situation, whether it is a back-clip battery or two mobile phones, it is crazy, things should not be like that.'
