New solid-state battery technology is here again!

New solid-state battery technology is on the scene! According to reports, cheap, high-capacity solid-state batteries may make previous practical ideas come true ahead of schedule.

It is reported that the solid-state battery product was developed by the Belgian research institute IMEC, and Panasonic also participated in the development of the electrolyte material. IMEC announced in June that it had developed a solid electrolyte lithium-ion rechargeable battery with a volume energy density of 425 h/L (Figure 1). It is assumed that lithium iron phosphate (LFP) is used as the positive electrode active material and metallic lithium is used as the negative electrode active material.

Figure 1 Achieving 1000 Wh/L in 2024

This figure shows the volume energy density changes of lithium-ion batteries using electrolytes and solid batteries developed by IMEC. As an electrolyte lithium-ion battery product, 400 Wh/L is already its standard value, and there have been examples of 700 Wh/L in the laboratory. If there is no breakthrough in the future, then 800 Wh/L may be its limit, but solid-state batteries will exceed this limit in the next few years. At present, all-solid-state batteries are not as good as electrolyte batteries, but from the growth trend in the figure, it can be seen that the annual growth rate of its energy density is almost linearly rising. At the same time, solid-state batteries will catch up after 2020, reaching about 1000 Wh/L in 2024, and the charging rate can reach 2-3c (20-30 minutes to charge).

Transition from liquid to solid?

The biggest feature of IMEC's ​​battery is its manufacturing process (Figure 2), which is the same as the current electrolyte battery. First, the positive electrode is formed, and then the liquid electrolyte is infiltrated into the positive electrode material.

Figure 2 Solidification of electrolyte during manufacturing process

An overview of IMEC's ​​entire solid-state battery manufacturing process (a): First, a positive electrode material is formed on a polymer, and a liquid material as an electrolyte precursor is added there, which is solidified to form a negative electrode layer. Unlike previous solid electrolytes, this has the advantage of being able to utilize existing lithium-ion battery manufacturing equipment to a certain extent (b).

The difference is that the electrolyte is dried and solidified to form the negative electrode. It is also relatively easy to implement. It only requires a slight change to the existing electrolyte battery equipment during mass production, so it can be well utilized. Therefore, even for all-solid batteries, there is no need to invest heavily in them. In fact, IMEC has basically established the technology for mass production of large batteries. The company plans to trial-produce batteries with a size of A4 and a capacity of 5Ah in 2019.

Since the electrolyte initially penetrates into every corner of the electrode in liquid form, the phenomenon of "small contact area between the electrode and the solid electrolyte and very high interface resistance" is unlikely to occur in solid batteries. From your point of view, which battery will have a larger market in the future?