Basic technology for using “lithium metal” for negative electrode

The research of the electrode materials for the lithium ion cell is currently in full flood. Lithium metal has been considered as the ultimate negative electrode material and studied for long time. The Li-ion cell capacity decreases for a relatively short time of period because of presence of the lithium metal deposition called lithium dendrite through the charging/discharging operation. For this reason, the lithium metal has not been used for the negative electrode of the Li-ion cell.

Prof. Dr. Kanemura et al. Tokyo Metropolitan University succeeded in developing a unique separator which inhibits the dendrite from growing.
In the experiment, no decrease of the cell capacity was observed after more than 2000 charge/discharge cycles. This fact leads to considerable increase of the energy density of the Li-ion cell and the cruising distance of the car carrying the battery. The researchers have successfully developed a production process capable of mass-producing the separators at low cost.

New technology for inhibiting dendrite growth:
Many studies have been made on the lithium dendrite deposition.
Most researchers have considered that the major cause for the dendrite deposition is that the lithium metal non-uniformly deposits on the negative electrode.
Dr. Kanemura et al. have developed anew a separator having a unique structure called a 3DOM structure, which enables the lithium metal to uniformly deposit on the negative electrode. The reversible charge/discharge capacity, when the unique separator is used, was 1000m Ah/g. The figure is about 3 times of the graphite materials currently used. Further increase of the reversible charge/discharge capacity is theoretically allowed. It was confirmed that no performance deterioration occurred after the charging and discharging operations were repeated.
(Written based on press release from NEDO)