Will the best choice for mobile batteries in the future be solid-state batteries?

After a period of fermentation and dissemination, Samsung's note 7 battery explosion has developed from technology news to social news, not only affecting the entire battery industry's nerves, mobile phone consumers have also begun to worry about mobile phone safety. So would it be better if Samsung were to switch to all-solid batteries? Because all-solid batteries have a prominent advantage, the safety is much higher than that of liquid lithium batteries and it is not easy to explode.

In fact, mobile phone makers have taken advantage of solid state batteries. Since 2012, Apple has been aggressively patenting all-solid-state battery technology, hoping to use the new batteries with high energy density, high security, and flexible potential for devices such as the iPad and MacBook, as well as flexible electronic devices that will be developed later. In November 2015, the U.S. Patent and Trademark Office released a new Apple patent related to solid-state battery charging technology -- solid-state battery charging technology for portable devices.

The all-solid battery can become the mainstream direction of battery research and industry's recognition of the next phase of battery development, and has a direct relationship with its unique performance.

High safety: Solid state batteries can completely prevent the direct reaction of atmospheric composition and lithium metals because their solid electrolytes can separate the positive side of the air from the negative side of the lithium metal, and the maximum operating temperature of the battery can be increased from the current 40 °C to higher., This allows the battery to adapt to a wider range of operating temperatures and a wider range of applications. Therefore, safety is one of the most fundamental driving forces for the development of the all-solid battery field.

High energy density: After the solid state battery replaces the diaphragm and electrolyte of the traditional lithium ion battery with the solid electrolyte material, the material system applicable to the lithium ion battery has also changed. The most central point is that it is not necessary to use the graphite negative electrode embedded in lithium., Instead, direct use of metal lithium as a negative electrode can significantly reduce the amount of negative material, so that the battery's energy density has been significantly improved. The increase in energy density is conducive to making batteries lighter. One of the development directions of new energy vehicles in China is lightweight. If solid batteries can be commercialized, they will contribute to this.

Flexibility foreground: because solid state batteries can be thin posture advantage, it has the potential to be further optimized into flexible batteries. The flexible battery developed from solid batteries can withstand hundreds to thousands of bends and ensure that performance is basically not attenuated. This type of battery is the best power choice for some wearable electronic devices. It is Apple's efforts to develop solid-state batteries that see the prospect of its softness.

However, the advent of a product always needs to go through various tests, solid state batteries are no exception. In all-solid lithium batteries, the solid-solid contact between the electrode and the solid electrolyte has a higher interface contact resistance than the solid-liquid contact. At the same time, the interface compatibility and stability also significantly affect the cycle performance of all-solid lithium batteries. And multiplier performance. In addition, solid-state batteries also face the development bottleneck of production processes to be increased and costs to be reduced.

In response to these problems, many scientific research institutions have made a lot of research and development work.

Sakti3, founded by Mali·saisiteli, a former professor of engineering at the University of Michigan, has developed a solid-state lithium battery made from flat panel televisions and solar panels. The battery, which uses "thin film deposition technology", costs only one-fifth of the current cost of lithium batteries. The energy density, however, is twice that of lithium batteries.

The research and development team of the Qingdao energy storage Industry Technology Research Institute has developed a series of all-solid polymer electrolytes with excellent comprehensive performance. The electrochemical window of the new all-solid electrolyte membrane can reach 4.6 V, and the thermal stability temperature of the electrolyte can reach at least 200 °C. When this electrolyte is used for all-solid lithium-ion batteries, After 1,000 charge and discharge long cycles, 92 % of the capacity is still maintained. At present, this kind of high-energy density and high-performance all-solid lithium battery has passed the 11000-meter full-sea depth simulated pressure warehouse cyclic pressure test, and it is expected to become the ideal energy power of the deep-water submersible such as the "Dragon" in the future.

Researchers at the Swiss Federal Institute of Technology in Zurich used Garnet as an electrolyte to enlarge the contact area between the solid battery electrode and the electrolyte, thus achieving the effect of faster charging of the solid battery and withstand the temperature of 100 °C.

SunCultureSolar applied solid-state battery technology to the energy storage field. It developed a new integrated solar panel with built-in solid-state low-voltage batteries and seamlessly integrated with inverters. This fully integrated product design can reduce the total cost of solar energy installation and storage by more than 50 %.

Solid state batteries contain no flammable liquid electrolytes, which can greatly improve the safety of batteries and will surely become an advanced technology in the battery industry. Since all countries in the world are in the initial stage of research and development of solid-state batteries, it is now the best period for the research, development, and industrialization of solid-state batteries, and it is also a great opportunity for the battery industry in China to achieve "leading" in the international community. In addition, the accumulation of research and development technology and experience on solid state batteries is also crucial for the future research and development of lithium sulfur batteries and lithium empty batteries.

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