The process triggered extensive surface diffusion of lithium, spreading the dendrites into an even layer. The researchers ramped up the self-heating effect by increasing the current density (charge-discharge rate) of the battery. This “self-heating” occurs through the charging and discharging process. Resistive heating (also known as Joule heating) is a process in which a metallic material resists current flow and, as a result, produces heat. The Rensselaer researchers’ proposed solution takes advantage of the battery’s internal resistive heating to eliminate the dendrite buildup. Self-Heating Technique Could Be a Game Changer

The best option would be a lithium metal system.” “For any significant new improvements, we must look elsewhere. “Lithium-ion batteries with carbon-based anodes are the best available option, but they can no longer keep up with the storage-capacity demand,” Koratkar said. Typically, one lithium atom is stored for every six carbon atoms, with the excess carbon material serving little more than deadweight. In this approach, lithium ions diffuse into and are stored within the carbon matrix, which isolates each lithium atom, thus preventing dendrite buildup. Industry has avoided the lithium dendrite problem by using carbon (typically graphite) anodes. When this happens, a short circuit takes place that renders a battery inoperable, or worse, causes a fire. This thorny buildup can eventually penetrate the separator and touch the cathode. In a battery with a lithium metal anode, repeated cycles of discharging and recharging cause dendrite buildup on the anode’s surface. When the battery is plugged into an outlet to recharge, the reverse happens: the lithium ions flow from the cathode back to the anode. The separator is saturated with a liquid electrolyte, which allows ions (charged atoms) to shuttle back and forth between the electrodes.Ĭhemical reactions produce electricity when positively charged lithium ions from the anode are transported to the cathode when discharging. Placed in between the electrodes is an insulating membrane that acts as a separator to prevent the electrodes from touching each other and shorting out the battery. Crossan Professor of Engineering at Rensselaer and corresponding author of the paper.Ī battery device is comprised of two electrodes - the cathode and the anode. “We have found that lithium metal dendrites can be healed in situ by the self-heating of the dendritic particles,” said Nikhil Koratkar, the John A. The researchers reported their findings this week in Science. Often, they grow long enough to create a short circuit between the electrodes, leading to a fire hazard.īut now a team of researchers at Rensselaer Polytechnic Institute (Rensselaer) has discovered a way to use internal battery heat to diffuse the dendrites into a smooth layer.

However, lithium metal anodes are plagued by “dendrite” buildup that takes place over repeated cycles of charging and discharging.ĭendrites are branchlike protrusions that emanate out of the lithium metal surface. Since the packing density of lithium atoms is the highest in its metallic form, batteries that use metallic lithium anodes can pack more energy per weight or volume than graphite-based anodes. But researchers are looking for ways to replace graphite with lithium metal as the anode to boost the battery’s energy density. In a lithium-ion battery, the cathode (positive electrode) is a lithium metal oxide while the anode (negative electrode) is graphite. Rechargeable lithium-ion, the dominant battery technology for portable electronics, is increasingly becoming the battery of choice for electric-vehicle and electric-grid energy-storage applications. MaThe Heat Is On: Temperature Heals Lithium Dendrites Researchers at Rensselaer have developed a new technique using heat to enable lithium-metal self-healing to eliminate dangerous dendrite buildup in battery anodes, paving the way for more powerful battery technologies By SCER Staff

Dendrite growth in batteries