SEM images of the Si electrode and the Li metal electrode after the 4V5s pulse at the 20th cycle, showing no signs of Li metal plating on the Si and Li metal. Credit: Science (2024). DOI: 10.1126/science.adn1749
A team of engineers, chemists and materials scientists at Stanford University has discovered that applying a short-duration voltage to certain types of anodes in Li-Si batteries can restore some of their ability. In their article published in the journal Sciencethe group describes how they experimented with batteries by applying an electrical charge to several types of silicon anodes.
Chengbin Jin and Xinyong Tao, both from Zhejiang University of Technology, China, published a Perspective article in the same journal issue describing the work done by the team.
It is common knowledge that lithium-ion batteries do not last very long. After several charge/recharge cycles, batteries begin to hold less and less charge until they become of little use and replacement becomes necessary. For this reason, some battery manufacturers have begun to investigate the possibility of using silicon anodes.
This idea could gain popularity since the Stanford team discovered that for certain types of Li-ion batteries, giving them a five-minute burst of electricity directly to the anode can restore some capacity.
Batteries with a silicon anode have a higher density than those made from other materials, increasing their capacity. Unfortunately, during use, some of the silicon begins to fragment, reducing capacity. In fact, fragmentation creates isolated pieces of silicon which are partly filled with lithium: they look like small islands, unusable to retain the charge.
In this new study, the research team found that applying electricity directly to the anode brought some of the insulated pieces back toward the anode, making them able to hold a charge again. After testing the charging of the anodes, the researchers tested batteries with pure silicon anodes. Applying electricity directly to their anodes restored their capacity to some extent.
During their experiments, the researchers found that the more electricity they used, the more capacity was restored, but there was a limit. Too much electricity caused electrolyte degradation. They also found that varying the duration of voltage application had an impact on capacity restoration. Eventually, they discovered that applying four volts for five minutes gave the best result: a 30 percent increase in capacity.
More information:
Yufei Yang et al, Capacity recovery by transient voltage pulse in silicon anode batteries, Science (2024). DOI: 10.1126/science.adn1749
Chengbin Jin et al, Electrical pulses rejuvenate batteries, Science (2024). DOI: 10.1126/science.ads9691
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