Continued from Vacuum Process Paves Way for 5V-class All-solid Battery (1)

The LNMO layer is as thin as 60nm. The thicknesses of the Li3PO4 layer and metal Li layer are 550nm and 500nm, respectively. The diameter of the negative-electrode layer of the cell is 0.5mm, and the diameter of LNMO is as small as 0.9mm.

The thin-film-type 5V-class all-solid battery prototyped by Tokyo Institute of Technology, etc (source: Tokyo Institute of Technology, etc)

While LNMO has been researched as a positive-electrode material for some time, the resistance of the interface between LNMO and solid electrolyte has been high. With the high resistance, a large amount of heat is generated at the time of rapid charging, halving the advantage of all-solid battery.

This time, by using the ultra-high vacuum process, etc, the group drastically reduced interface resistance, it said. Also, the active energy is as low as 0.3V, making rapid charging easy. This is equivalent to the active energy of solid electrolyte used for all-solid Li-ion batteries using a conventional positive-electrode material, the group said.

Moreover, the stability of the new battery is high. When it was repeatedly charged/discharged 100 times at a high speed with a current density of 14mA/cm2, its capacity did not decrease, according to the group.

The changes of (a) charge/discharge characteristics and (b) capacity at the time of repeatedly charging/discharging the battery 100 times at a high speed (source: Tokyo Institute of Technology, etc)

As a result of the latest research, the group found that interface resistance can be lowered even with a 5V-class positive electrode depending on manufacturing process. If this mechanism is clarified, it might become possible to realize an equivalent interface resistance with other processes.

Original Japanese article