Lithium metal anode batteries have much higher energy densities than graphite anodes, but they have also been unable to commercialize them because of severe dendrite problems. However, scientists have now discovered that they can be cycled at high current densities. Discharge enhances the self-heating effect of the battery. This action can even 'cure' the dendritic structure of the lithium battery.
Rechargeable lithium-ion batteries are the main applications for consumer electronic products, and are increasingly becoming the battery of choice for electric vehicles and grid energy storage applications. The positive (cathode) is lithium metal oxide, and the negative (anode) is graphite. But scientists Did not give up the higher density of lithium metal batteries, tirelessly trying to find a way out for more powerful lithium metal batteries.
Researchers at the Rensselaer Polytechnic Institute in the United States have now found a way to use cell internal thermal energy to diffuse dendrites into a smooth layer, or as described by Nikkhil Koratkar, a professor of materials science and engineering at the head of research. Dendrites can be repaired in situ by the self-heating effect of the battery. The paper is published in the journal Science.
We know that a battery consists essentially of a cathode, an anode, an electrolyte, and a separator. The separator is located between the two electrodes so as to prevent them from contacting each other to short-circuit the battery. In addition, the pores of the separator that are filled with the electrolyte are ions (charged atoms) that shuttle to the electrodes. Between the channels, the more electrolyte the separator absorbs, the higher the ion conductivity.
When the battery discharges, the positively charged lithium ions on the anode are transmitted to the cathode to generate electricity; when the battery is charged, lithium ions flow from the cathode back to the anode, and the lithium metal anode is used in the process of repeated charge and discharge, and the anode surface is easily exposed to lithium. Non-uniform deposits form dendrites, and these thorny deposits eventually penetrate the separator and come into contact with the cathode, causing the battery to short circuit, causing a risk of explosive fire.
The use of graphite as the anode avoids the lithium dendrite problem and is currently the best battery option, but soon, they may not be able to keep up with the storage capacity requirements.
To make lithium metal batteries flourish, the researchers proposed a solution that uses the battery's internal resistive heating (Resistive heating) to eliminate dendrite accumulation. Resistance heating (also known as Joule heating) is a metal material that resists current flow. Therefore the process of heat generation, this 'self-heating' effect can occur through the charge-discharge process.
The researchers then increased the current density (charging-discharging rate) of the battery to increase the self-heating effect. It was found that this process allows the dendrite to spread evenly and smoothly, achieving the effect of 'cure'. The same results were obtained in the lithium-sulfur battery experiment. When the battery is not in use, it can achieve the self-healing effect of the battery by cycling several cycles of high-rate charge and discharge.
The research seems to have a very promising prospect. Supercharging charging can rejuvenate the battery, prevent short circuits caused by dendrites, ensure the battery is safer and have a high energy density, but does this prevent the battery capacity from rapidly deteriorating? It may be necessary for the team to further study. Now.
