The next generation of lithium-ion batteries-solid batteries?

In the final days of 2017, the famous Japanese spark plug manufacturer NGK announced that it will vigorously develop solid-state battery technology to prepare for the era of "no internal combustion engine" in the future.

Takio, senior engineering and R&D general manager for NGK, said: "We realize that the industry will inevitably shift from internal combustion engines to battery-powered vehicles to some extent, eventually leading to the obsolescence of our spark plugs and oxygen sensor business. The reason NGK is involved in solid-state batteries is that its advanced ceramic technology will provide an advantage for the development of solid-state batteries.

In fact, in the solid-state battery research and development, there have long been a number of enterprises first. Several established car makers, including Honda, Hyundai, and Toyota, are developing solid-state battery technology. And the new Fisk and Dyson, the new vacuum cleaner maker, is planning to use solid-state batteries to usher in the era of electric cars.

Perhaps many friends are still unfamiliar with the concept of solid-state batteries, but some people in the industry think it will be the next round of power battery hot spots after the three-element lithium battery. It is necessary to understand the characteristics of this new field that is still in the accumulation of technology.

Solid state batteries are batteries that use solid electrodes and solid electrolytes. Because the power weight of solid state batteries is relatively high, it is considered to be an ideal battery for electric cars. The traditional liquid lithium battery is vividly referred to as a "rocking chair battery." The two ends of the rocking chair are the positive and negative poles of the battery and the electrolyte(liquid) in the middle. Lithium ions, like excellent athletes, run back and forth at both ends of the rocking chair. During the movement of lithium ions from positive to negative to positive, the battery charging and discharging process is completed. The principle of solid-state batteries is the same, except that their electrolytes are solid, and the high-density structure allows more charged ions to gather at one end to conduct more current, which in turn increases battery capacity. So, with the same amount of electricity, the solid cell volume will become smaller. Not only that, due to the absence of electrolytes in solid-state batteries, storage will become easier. When used on large equipment such as automobiles, there is no need to add additional cooling tubes, electronic controls, etc., which not only saves costs but also effectively reduces weight..

Since the basic development direction of lithium-ion batteries is to achieve higher energy density, Japan and China plan to increase the energy density of the power battery core to 500 W/kg by 2030. Considering the energy density, the limit of the liquid electrolyte battery cannot be higher than 500Wh / kg, while the current energy density of the all-solid lithium battery can reach about 400Wh / kg, and the estimated maximum potential value is 900Wh / Kg.

In addition, in terms of safety, the advantage of all-solid lithium batteries is very obvious. Solid electrolytes are non-flammable, non-corrosive, non-volatile, and non-leakage fluids. At the same time, they also overcome the phenomenon of lithium dendrites, and the self-ignition probability of cars equipped with all-solid lithium batteries will be greatly reduced.

Japanese companies are still at the forefront.

Although Toyota is obviously lagging behind in plug-in technology, research and development of solid-state batteries and hydrogen fuel cells have been very tight. They plan to replace lithium batteries with solid batteries by 2020, with energy density three to four times that of lithium batteries. Toyota will commercialize all-solid batteries by 2020 and use lithium-air batteries in the coming years, said Shigekizuki, a senior material engineer at Toyota.

On November 24, 2016, Mitsui Metal released the sulphide solid electrolyte for the next generation of lithium ion secondary batteries. Mitsui Metal will cooperate with battery manufacturers and auto manufacturers to achieve mass production by 2020.

Hitachi is also very advanced in the development of solid-state batteries. Takashi Tanisho, president of Hitachi, said samples of solid-state batteries have been sent to potential customers in thespecial and automotive industries. In addition, Hitachi is working with an undisclosed Japanese battery maker to refine some details and put solid-state batteries on the market by 2020, and may not sell under Hitachi's brand. In fact, Hitachi has maintained a leading position in cutting-edge technology, and Hitachi has developed a lithium-ion battery technology for a pure electric car that has a life of about 400 kilometers.

European and American companies are equally aggressive

As early as 2015, Bosch Group, an auto parts manufacturer, successfully acquired Seeo Battery Co., a company based in Haiwodeshi, California. Seeo's new generation of solid-state lithium-electron batteries has the ability to increase the battery's energy density from 50 % to 100 %. Currently, batteries with an energy density of 350 Wh/KG have been developed, which is about twice the battery density in electric vehicles that are currently used. density. Seeo's DryLyte solid polymer electrolyte is not volatile or flammable, which means that the electrolyte can be used at higher temperatures.

In November 2017, the emerging electric car brand Fisker applied for a patent for a solid-state lithium battery with a maximum life of 800 kilometers and a charge of only 1 minute. Fisker's solid state battery project leader is the founder of Sakti3, a solid state battery company owned by Dyson. In 2015, Sakti3 claimed to have developed a new solid-state battery with a cost of up to $100 per watt-hour and an energy density of up to 1,000 watts/kg. Fisker said in his press conference that solid-state batteries have many restrictions, such as low power and low rate capabilities, which are caused by layered electrode structures and low temperatures. Fisker's charging technology uses a three-dimensional electrode structure, which makes the surface area of the electrode 25 times larger than the area of the planar film. This structure can adapt to different voltage and shape factors, and the energy density is 2.5 times that of a lithium battery.

In addition, BMW and Apple have already started research and development on solid-state batteries.

Chinese companies have also begun to layout

In electric vehicles, Chinese companies have always kept pace with the world. On August 9, 2017, the Polymer Solid State lithium battery Project of China Gas Battery(Zhejiang) started construction in the Songyang Sub-district of Lishui Ecological Industrial Cluster.

As early as the end of 2016, the Ningde era has also revealed its determination to deploy "solid-state batteries." The Ningde era conducted a survey of companies making solid-state batteries around the world before making solid-state batteries. In the R&D process of the Ningde era, attention was also paid to the manufacturing of solid-state batteries. The entire manufacturing process of solid-state batteries is different from that of traditional lithium-ion manufacturing processes and requires new equipment and new processes. Therefore, the Ningde era also carries out the process at the same time. R&D.

Solid state batteries have a good Outlook, but the biggest test is price. Liquid lithium batteries cost about 200 to 300 dollars per kilowatt-hour. If you use existing technology to make solid-state batteries that power smartphones, the cost will reach 15,000 US dollars, and the cost of solid-state batteries that can power cars will be staggering. 90 million US dollars. The main reason for the high production cost of solid-state batteries is that they are inefficient.

Small electricity evaluation:

Solid state batteries have two biggest advantages, one is energy density and the other is safety. These two are exactly where the hottest three-element lithium battery is difficult to break, so it will not be surprising that it is the wind outlet for the next round of batteries. However, due to the lack of technical maturity of solid-state battery preparation technology, the number of enterprises that can form large-scale production capacity is limited, and there are still many difficulties that need to be overcome by large-scale technology expansion. It is still in the stage of R&D and trial production. However, it can be expected that with the continuous development of R&D and industrial technology, the scientific and technological problems of solid-state batteries will gradually be eased. At present, you can see that the technology that may be promoted in the future also includes fuel cells, Supercapacitors, aluminum air cells, magnesium cells, etc.. Whether solid batteries can stand out requires many efforts.

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