Brief description of the development of fast charging and solid state batteries

Guangzhou Automobile officially announced its entry into the power battery field.

This news said that small is not small, said that large is not very big, because the driving power battery Pack is already the general trend, after all, there is no battery package design technology, there is no way to talk about R&D.

Compared with the new lithium electric technology, which is almost impossible to be applied on a large scale in the short term, the improvement in the design of power cell structure has more practical benefits. You know, from monomer to battery system is the weak link of domestic new energy industry.

But in the long run, improving the performance of electric vehicles through battery system innovation is the fundamental way to improve competitiveness. The development of the current battery system is mainly divided into two clocks, one is the high specific energy direction represented by solid batteries and high nickel ternary; The other is the direction of high magnification represented by fast charging.

Raising energy density has always been the focus of research at home and abroad. The high-power direction is mainly reflected in high power and fast recharging batteries. It is more popular in hybrid cars and some subsectors. Israel's 5min flash black technology that shocked the world last year is typical of this direction. In addition, Japan's Toshiba is also very prominent in this area, and China is headed by micro-macro power.

"The endurance is not enough, fast charging," although to a certain extent, fast charging can greatly relieve consumer mileage anxiety, but due to the large load on the grid, it has been criticized by the industry. However, recently, Japan's Toshiba and Porsche have made breakthroughs in the fast-charging field, which may point the way for the fast-charging field.

Here's a look at new technologies and events in the lithium industry this week.

1, Toshiba new generation SCiB car battery charging 6 minutes continue 320km

A few days ago, Toshiba officially announced that it has successfully developed a new generation of lithium ion batteries for SCiB vehicles, which has the advantages of high energy density and rapid charging. According to Toshiba's official measured data (Japanese JC08 standard), this new type of lithium ion battery can reach 6 minutes of charging and travel 320 kilometers, which is three times that of traditional lithium ion batteries.

Toshiba's official website stated in the announcement that the company launched Super Charged Battery (SCiB) in 2008. It uses lithium titanate as a negative electrode and can achieve rapid charging and discharge, with a life of up to 15,000 times. It can also be used in an environment of minus 30 °C.

Through technical research and development, Toshiba developed a lithium ion battery with titanium niobium oxide as the negative electrode material on this basis, and its lithium ion storage capacity is twice that of graphite as the negative cathode material lithium battery. At the same time, Toshiba also showed a sample of a new lithium battery, 50Ah, only 111mm X 194mm X 14.5 mm. It is reported that its charging can reach 90 % of the electricity in 6 minutes, and the lithium battery of traditional electric vehicles can only be filled with 80 % in 30 minutes even if it is filled quickly.

It is reported that after the new generation of lithium batteries have been charged and discharged 5,000 times, they can still maintain more than 90 % of the battery capacity, and the loss rate is extremely low. In addition, rapid filling can also be achieved at a low temperature of minus 10 °C. Toshiba said the new titanium niobium oxide anode and the new generation of SCiB batteries are a disruptive advance that is expected to have a significant impact on the life and performance of electric vehicles. It is reported that the new generation of SCiB batteries are expected to be commercial in 2019.

Comments: in fact, before the heat of solid-state batteries rose, fast charging technology has always been the focus of corporate research, but no practical progress has been achieved, because it is difficult to take into account energy density, cycle life, and safety under the premise of ensuring fast charging. What is outstanding in the field of fast charging in China is micro-macro power. The performance is relatively comprehensive, but it is still a long way from being accepted by consumers. However, the next generation of energy-type lithium batteries represented by solid-state batteries has not reached the level of industrialization. It is still difficult to say who will gain an advantage in the market in the future. The author personally believes that fast-charging batteries are more suitable for hybrid models, as well as other special subdivision areas.

2, technology to increase fuel cell life

The core factor determining the performance of solid oxide fuel cells is the cathode where an oxygen reduction reaction occurs, usually using an oxide with a perovskite structure (ABO3) in the cathode. However, although calcium titanium oxide has high performance in the initial operation, its performance decreases over time, limiting its long-term use. In particular, the conditions of the high-temperature oxidation state required for cathode operation lead to surface segregation, in which the second phase such as strontium oxide (SrOx) accumulates on the oxide surface, resulting in a decrease in electrode performance.

Using computational chemistry and experimental data, the team of Professor WooChulu Jung of the Department of Materials Science and Engineering observed that the local compression state around the Sr atom in the perovskite electrode lattice reduced the strength of the Sr-O bond, thereby promoting the separation of strontium. The team found that the local variation of strain distribution in calcium titanium oxide was the main cause of strontium surface separation. Based on these findings, the team added different sizes of metal to the oxide to control the lattice strain in the cathode material and effectively inhibited strontium segregation.

Professor WooChulu Jung said: "This technology can be achieved by adding a small amount of metal atoms to the material synthesis process without the need for additional processes. I hope that this technology will be effective in developing high-durability calcium titanium oxide electrodes. "

Comments: The life of fuel cells is actually very complicated. The biggest problem at present is caused by the operating conditions of cars. The current changes caused by starting and stopping, accelerating, and decelerating are serious for the attenuation of membrane electrodes. This is why fuel cell vehicles are currently using hybrid power system assemblies because the battery can carry and reduce the impact of current changes on fuel cells. Therefore, simply from the experimental research of the fuel cell itself to increase the life span, the gold content is not high, or the actual benefit is very small.

3, super fast charging Mission charging voltage can reach 800V

Porsche said that MissionE will use a high-pressure ultra-fast charging system of 800V. Compared with the more popular 400V charging system, it can theoretically shorten the charging time by double, allowing MissionE to charge for 20 minutes and travel 400 kilometers. It is enough to drive from Nanjing to Shanghai. Compared with the traditional way of refueling, 20 minutes is not unacceptable. It is worth mentioning that there are two main solutions for high-voltage fast charging and low-voltage fast charging on smart phones, and it is actually similar for electric vehicles because of the higher requirements for low-voltage fast charging for cable carrying capacity. So Porsche finally chose high pressure fast charge.

Porsche Mission has increased the voltage of some vehicle electronic control systems to 48V, which can provide more power for related components, followed by performance improvements. Similar practices have previously appeared in Bentley Bentayga. As for other vehicle-assisted systems, it is maintained at the standard 12V.

Comments: In fact, there are several bottlenecks in fast charging, the first is the fast charging technology of the battery itself, followed by high-power charging piles. However, these two points have not been effectively solved. The 800v fast charge introduced by Porsche can not be used on a large scale under the existing conditions. It is more a demonstration. But at least Porsche's advanced technology proves the feasibility of fast charging in the future.

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