The development of next-generation batteries that are essential for electric vehicles and natural-energy-based energy storage has become very popular, with super-materials that have outgrown traditional lithium-ion batteries in terms of cost and performance, etc. Many countries have already started the ban on petrol-powered cars Discussion, especially for the electric car power supply is particularly concerned about the focus of this article on the revolutionary breakthrough of the driving force of the battery, that is, the recent trends in the attention of new technologies were followed up.
Asahi Kasei's honorary technical director (fellow) Mr. Yoshinobu think: a new generation of batteries, the most practical is the all-solid-state battery as the father of lithium-ion batteries (Note: Goodenough with the invention of lithium cobalt oxide, the famous lithium-ion The inventor of the electrolyte), one of the Nobel Prize Laureates in Chemistry, believes it makes perfect sense that all-solid-state batteries are promising.
All-solid type, the driving force of EV
Batteries are made up of positive and negative electrodes and an electrolyte that serves as a lithium ion transport channel between them.The current lithium-ion battery uses an extremely flammable organic solvent as a solution to the electrolyte.The all-solid-state battery uses a flame-retardant solid electrolyte Replace the organic solvent electrolyte, safety will be greatly enhanced.
Taking the opportunity of joint development of new solid-state electrolytes by Prof. Kenno Kanno of Tokio Engineering in 2011 and Toyota Motor Co., Ltd., all-solid-state batteries have started to attract people's attention. Lithium ions are extremely easy to pass through the solid electrolyte layer and their ionic conductivity even exceeds Traditional electrolyte level.
If the ion conductivity is high, the output power of the battery will increase.It will be greatly improved when it is mounted on an electric vehicle and the driving performance such as quick start and acceleration that can be achieved by requiring a large battery power.
DongGung University and other research teams are continuing to advance material improvement by changing the element types, etc. In 2016, the ionic conductivity of the solid electrolyte reached more than twice that of the organic electrolyte and the power density of the cell reached more than three times. The solid-state battery for this battery after repeated charge and discharge 1000 times, the capacity is almost no attenuation, to meet the requirements of long-life battery.
Fast charging is possible.However, as with the traditional lithium batteries in the rapid charging also dendrite and other internal problems, leading to internal short circuit hidden problems.If this problem is solved, the problem of fast charge within a few minutes Can be solved.
Current solid electrolytes, because of their sulfur content, generate hydrogen sulfide gas when exposed to moisture in the air, and laboratories require special glove boxes that operate within the seal and outside air must not enter the glove box, The assembly of the battery into the battery needs to be operated under such special conditions, and the problem is not solved until mass production is a technical barrier. (The Toyota-Mitsui team completed the production process as early as two years ago, but can not make it public)
Solid-state battery technology is the core of the electrolyte, that is, to improve the ionic conductivity of the electrolyte. 'If the ion conductivity is 10 times the normal electrolyte, solid-state battery, all the problems solved.' Yoshino Honorary Director said.
Professor Kanno and others developed a solid electrolyte containing no rare metal elements in 17 years, and although the conductivity dropped to almost the same level as that of the conventional electrolyte, the cost was reduced by 1/3. If it is desired to suppress hydrogen sulfide gas (Note: This is also the distress of Professor Kanno team, their laboratory synthesis of Ge-free sulfide electrolytes far below the performance of the Mitsui team has been the size Chemical production of electrolytes, Toyota has basically terminated the project funding)
The choice of electrode that determines battery capacity is also difficult, says Professor Kanno: 'Many research teams are looking for materials that are suitable for the electrode (to match the electrolyte).'
Takada Kodomo, deputy director of Japan's National Institute for Materials Research, has developed a new system of negative electrode materials, mainly silicon, whose negative electrode capacity can be To about 10 times the existing lithium-ion battery. The entire battery capacity is expected to be increased by about 50% .Si partially oxidized structure design, silicon can be uniformly expanded and contracted, the collapse of the silicon electrode has been effectively resolved .
Deputy Chief Takata said: 'Although the principle can be verified, it is necessary to develop technologies that are suitable for mass production.' Currently, there are problems such as complicated steps of attaching a silicon thin film to a substrate.
Toyota plans to commercialize all-solid-state batteries by the first half of 2020. If the technical challenges can be met by mid-2020, solid-state batteries will no longer be a dream in EVs around 2030. Of course, the full range of existing lithium-ion Batteries are the most critical factor in the promotion of solid-state batteries.
Break barriers high concentrations of electrolyte
Lithium-ion batteries were first commercialized by companies such as Sony and Asahi Chemical in 1991. With subsequent improvements, although the performance has been gradually increased, it is close to the upper limit of technology. At present, the technology that can break this barrier hopes that With the solid electrolyte properties of similar high concentrations of electrolyte and then by improving the accompanying electrode materials, etc., to further improve the performance of lithium-ion batteries.
Professor Yasuo Watanabe of Yokohama National University said: 'By making the electrolyte thicker, it becomes a solid-like property. "It is as solid as a non-volatile and has a non-flammable characteristic, which is not exactly the high safety we want Batteries? Professor Watanabe, who successfully developed the equivalent of about 3 times the current concentration of electrolyte high concentration of electrolyte.
In a typical electrolyte, only a part of the organic solvent molecules are bound to lithium ions, and unbound free molecules can leave the electrolyte and volatilize freely, which easily decompose during repeated charging and discharging to form electrolytes, electrodes and the like Of the main reason for the deterioration is notable is the so-called 'polyether' organic solvent, it has the nature of the lithium ions surrounded by the mix ratio work hard and found that a variety of molecular forms of polyether almost All with lithium-ion combination of this electrolyte can effectively prevent the deterioration of electrodes, etc., to develop long-life batteries.
Professor Yamada, a professor at the University of Tokyo, who succeeded in reducing the battery charging time to one-third that of usual lithium-ion batteries by using high-concentration electrolytes in 2014. Professor Yamada said: "In the past, if the common sense reached high Concentration, then the battery reaction speed will be slow, high concentrations of electrolyte is considered not suitable for lithium-ion batteries.
In 2017, we developed a strong non-flammable electrolyte that also has a lithium-ion battery extinguishing agent that uses flame-retardant trimethyl phosphate as an organic solvent and will not burn even near fire, If it is heated to 200 degrees Celsius, it will generate a flame that can extinguish the flame, so it can become an opportunity to develop a non-sparking battery that inhibits the ignition of a lithium battery.
Although a variety of functions of the new battery worth the wait, but the main problem is the cost of laboratory synthesis of these materials used in the battery, the price is extremely expensive Professor Yamada said: 'In the future to achieve mass production, the material is no longer a special, The cost of the price will naturally fall.
One of the ways to improve the electrode material is to develop a new material that can be mixed with the existing positive electrode material to increase the capacity and output power of the battery. The optical glass leading company Ohara Manufacturing Co., Ltd. (Mitsui Systems) Additive material with reduced capacity under fast charge and low temperature conditions. This independently developed glass material called 'LICGC' can be mixed into the cathode material of solid state battery. Add LIGGC to the trial battery in the cathode material, The battery discharges at a rate three times faster than the normal Li-Ion battery (LIB), which increases capacity by about 40% and increases by about 25% at minus 20 degrees Celsius. This battery is expected to be suitable for use in cold places In other experiments, improvement of the charging time and output power was also confirmed.
Okayama University, Temple of the West Gui Zhi assistant to the successful development of a fast charge and discharge related positive.He focused on research can attract lithium ion metal oxide.On the surface of the cathode material coated with titanium and barium and other material particles, The trial of the battery can be 5 times the usual lithium-ion battery speed charge.
Electric cars (EV) even take a few minutes to charge quickly, which is the biggest disadvantage EVs can make when compared to a fuel-efficient car that can be started right away, says Temple's TA: "If you can apply new technologies , EV charging time is expected to be shortened. "Through the improvement of the electrolyte and the electrode, the dawn of improving the performance of the lithium-ion battery was seen.
As long as breaking the existing common sense to continue to develop, I believe in the existing lithium-ion battery based on the way to open up a new generation of batteries to the next generation of the road.
