Secondary Lithium Metal Batteries
Lithium-ion batteries have been a standard battery chemistry for electronic devices since their introduction in the early 1990s. However, emerging applications including portable energy storage, electric vehicles, and stationary storage for renewable energy generation require batteries that can store more energy and are less expensive than current lithium-ion batteries can hold. Lithium metal batteries could more than double the improvement in storage and, respectively, the driving range of electric vehicles, but serious materials problems have prevented development of practical lithium metal batteries.
Project Innovation + Advantages:
Cornell University will develop a new type of rechargeable lithium metal battery that provides superior performance over existing lithium-ion batteries. The anode, or negative side of a lithium-ion battery, is usually composed of a carbon-based material. In lithium metal batteries, the anode is made of metallic lithium. While using metallic lithium could result in double the storage capacity, lithium metal batteries have unreliable performance, safety issues, and premature cell failure. There are two major causes for this performance degradation. First, side reactions can occur between the lithium metal and the liquid or solid electrolyte placed between the positive and negative electrodes. Second, when recharged, branchlike metal fibers called dendrites can grow on the negative electrode. These dendrites can grow to span the space between the negative and positive electrodes, causing short-circuiting. To overcome these challenges, Cornell proposes research to pair a variety of cathodes with a lithium metal anode. The work builds upon recent theoretical and experimental discoveries by the team, which show that a class of structured electrolytes can provide multiple mechanisms for stabilizing lithium metal anodes and suppress dendrite growth. The team will also develop structured electrolyte coatings that provide barriers to oxygen and moisture, but do not impede lithium-ion transport across the electrolyte/electrode interface. Such coatings will suppress the unwelcome lithium metal/electrolyte reactions and will also enable manufacturing of lithium metal batteries under standard dry room conditions. The structures developed could also be used in batteries based on other metals, such as sodium and aluminum that are more abundant and less expensive than lithium, but also affected by dendrite formation.