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Description
Conventional lithium-ion batteries that utilize graphite as an anode material have given modern society the ability to store energy reliably. However, current state-of-the-art batteries are nearing reaching their theoretical energy density limits. As a result, the development of anode-free lithium metal batteries is quickly growing due to the 10 times improvement in theoretical energy density. These anode-free cell designs, though, have major limitations regarding lithium plating and stripping efficiencies associated with dendrite growth. Considerable effort has gone into understanding the underlying causes of these inefficiencies and designing electrodes that reduce dendrite growth and lithium loss. One scalable surface treatment for the current collectors used in anode-free lithium batteries is cold spray. Cold spray is an additive manufacturing process in which powder particles are accelerated to a critical velocity, enabling bonding to a substrate via extreme plastic deformation. Cold spray coatings have been shown to increase both surface area and defect concentration, resulting in a higher surface energy. In this work, the effect of this cold sprayed surface modification will be studied with respect to localized dendrite growth on copper current collectors. To accomplish this goal, the redesign of a cold spray deposition system located in SDSU’s Interface Design Lab (IDL) was completed. The redesign consisted of adding, removing, and replacing components as well as conducting a thorough system cleanout. Redesign and reorganization of the system controls software and external circuitry was also completed. Testing and troubleshooting of the system was performed to ensure it could produce an even coating over a considerable electrode area. The effects of the various forms of cold sprayed coatings were tested in coin cells as well as in the IDL’s unique visual cell. Visual and cycling data was collected for the different fabricated current collectors and the results are discussed. Visualization cell data shows that cold spray deposition significantly affects lithium dendrite growth. Coin cell cycling data showed that the cold sprayed current collectors increased the number of cycles to failure.
