Lithium ion batteries lose their charging capacity as they get older. Because they’re proposed to be used in hybrid and electric cars in the near future, it’s an important issue to deal with if we want to have lower maintenance costs and, generally speaking, greener batteries, because of prolonged lifetime. Some Ohio State University researchers did an experiment to see why the batteries lose their original capabilities.
First, two OSU researchers (Yann Guezennec and Giorgio Rizzoni) tested the batteries in various temperature and humidity conditions, ranging from extreme Alaskan colds to high temperatures.
Then, another group of researchers (Bharat Bhushan, Suresh Babu, and Lei Raymond Cao) slit them open and studied the batteries’ interiors, establishing why they had been losing capacity over time.
Using infrared thermal imaging, the three scientists analyzed for flaws in each electrode. After that, they studied the issues they found more closely, through various advanced microscopy techniques. Their results showed that the electrodes bear the guilt of aging. The finely-structured nanomaterials on the electrodes had coarsened, allowing rapid charge and discharge.
Moreover, by using neutron depth profiling, the researchers concluded that part of the lithium responsible for exchanging electrical charges between the anode and the cathode was no longer available. They found that lithium embedded irreversibly in the cathode. “We can clearly see that an aged sample versus and unaged sample has much lower lithium concentration in the cathode,” said Rizzoni, director of the Center for Automotive Research at OSU. “It has essentially combined with anode material in an irreversible way.”
The researchers suspect that the unavailability of the lithium ions is also due to the coarsening of the electrode materials. This study offers important clues to other scientists, who study electrode manufacturing technologies, as to how to approach the issue in the future and develop better materials, so that the lithium doesn’t attach to them that quickly.
With batteries having a longer lifespan, electric cars could truly be a viable means of transportation and the battery technology wouldn’t pollute as much due to the lithium extraction technology, which strips forests off mountains, thus contributing to global warming just like fuel-sipping vehicles.
Anyway, my opinion is that hydrogen is the ultimate energy carrier throughout the Universe and here on Earth, so we should reach that conclusion and the technological means to store it properly, one way or the other. It’s only a matter of time, though…