10 kilograms of petroleum is enough for a conventional car to travel 100 kilometers and longer. But for the same distance, an electric car would need more than 100 kilograms of lithium ion batteries. The distance of electric vehicles is limited by the insufficient energy density of the battery – the amount of energy that one kilogram of battery can store and release. After years of development, the energy density of lithium ion batteries is approaching its theoretical operation limit. A leap forward in energy density would require a brand new type of battery. This is why lithium metal batteries are garnering so much more attention nowadays. By using lithium metal, which is a pure substance, instead of the graphite anode used in lithium-ion batteries, the theoretical energy density of a lithium metal battery can be several times higher than that of conventional lithium ion batteries.
However, this technology has a major concern: safety. During the charging and discharging processes of the lithium metal battery, an unwanted structure, called the lithium dendrite, may form on the surface of the electrode. Lithium dendrite can decrease the energy density of the battery, and in the worst case, cause short circuits in the battery, which can lead to overheating, fire, or even explosion. This is the problem that has hindered the development of lithium metal batteries for many years.
Yingying Lu has been dedicated to energy-related fundamentals and safety problems in batteries for years. By revealing the underlying mechanisms of the formation of lithium dendrite, she found new ways to undermine or even eliminate the dendrite problem. Lu demonstrated several methods that can realize the stable electrodeposition of lithium along the electrode surface. She has also successfully created a nearly dendrite-free deposition, and furthermore, has developed new electrolytes and electrodes, making the energy storage capacity of lithium metal batteries several times higher than today’s lithium ion batteries. High energy density and safety can be achieved simultaneously for this promising energy carrier. “She has single-handedly solved a problem widely regarded as a grand-challenge problem in the batteries field,” said Prof. Lynden A. Archer, the National Academy of Engineering in US, Professor of Cornell University, and Lu’s advisor during her Ph.D. studies.