Reduction of irreversible capacity by laser drilling and predoping to SiO negative electrodes for lithium-ion secondary batteries (LIB)
Overview of traditional issues and research and development
The capacity of SiO, which is being developed as a negative electrode material for lithium-ion secondary batteries (LIB), is approximately 1500 mAh/g, and is much larger than the current graphite negative electrode (371 mAh/g), so high energy density of batteries is expected.
On the other hand, SiO has been difficult to put into practical use until now because the capacity that can actually be discharged for the initial charging capacity is small.
Through our joint research with Yamagata University, a national university corporation, we have succeeded in prototyping a battery that has significantly reduced irreversible capacity by enablin1g the SiO negative electrode with laser perforation to be charged in advance with the SiO negative electrode, which is equivalent to the predoped irreversible capacity of lithium ions in a simple manner.
Electrode configuration using laser perforated electrode
| 正極 | 負極 | |
|---|---|---|
| live material | NCA | SiO |
| aperture ratio | 1.5% | 0.5% |
| Table 1: Electrodes and battery configuration used in the prototype | ||
 Figure 3: Roll-to-roll laser drilling mass production machine |  Figure 4: Laser drilled SiO anode (transmitted light view) |
| Comparison between a conventional LIB configuration and a battery fabricated with laser drilled electrodes |
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Prototype and evaluation results of small batteries
Charge/discharge curves of a battery consisting of an NCA cathode and a pre-doped SiO anode
- By laser perforation of the SiO negative electrode, it was confirmed that lithium ion predopsis to SiO is possible even under the conditions of 0.5% aperture (Fig. 2, from Yamagata University-like evaluation data).
- The reverse capacity of the charge-discharge first cycle is greatly reduced by pre-doping, and the ratio of the discharge capacity to the charging capacity is 25% in the case of no predop.
In this system, it has improved significantly to 90%. - The theme of this research and development is the 59th Battery 2Symposium in Osaka, “Development of Li predoping technology in the si-based negative electrode using laser drilling technology” at the 59th Battery Symposium in Osaka.
Thanks
This result is a part of the results of the implementation of the new energy and industrial technology development organization (NEDO) of the National Research and Development Corporation.
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