Electrodeposition of lithium metal thin films and its application in all-solid-state microbatteries

Abstract

Lithium metal thin films are deposited via an easy electrochemical route using standard carbonate based electrolyte with LiPF6 salt. Deposited films exhibit self-aligned nanorods structure without any dendritic growth. The electrochemical performance of such lithium electrodes is evaluated in coin cell configuration versus silicon thin films and no obvious difference in behavior is observed between electrodeposited lithium thin films and bulk lithium metal foils. The process is then used to manufacture all-solid-state thin film battery stacks composed of a silicon cathode, LiPON as solid electrolyte, copper as conductive layer for the electrodeposition process and electrodeposited lithium as anode material. Finally, the electrochemical performance (cycle life, specific capacity and curve shape) is close to those obtained with standard evaporated lithium. This new lithium film deposition technique is suitable for 3D textured or high roughness substrates and limited to electronic conductive surfaces. In the end, this enables a direct patterning of the lithium anode layer. Therefore, considering that all other microbattery materials can be structured by photolithography, the Li electrodeposition could avoid using shadow masking technique during the all-solid state microbatteries manufacturing process.