Atomic/Molecular Layer Deposition of Lithium Terephthalate\nThin Films as High Rate Capability Li-Ion Battery Anodes

Abstract

We demonstrate the fabrication of\nhigh-quality electrochemically active organic lithium electrode thin\nfilms by the currently strongly emerging combined atomic/molecular\nlayer deposition (ALD/MLD) technique using lithium terephthalate,\na recently found anode material for lithium-ion battery (LIB), as\na proof-of-the-concept material. Our deposition process for Li-terephthalate\nis shown to well comply with the basic principles of ALD-type growth\nincluding the sequential self-saturated surface reactions, a necessity\nwhen aiming at micro-LIB devices with three-dimensional architectures.\nThe as-deposited films are found crystalline across the deposition\ntemperature range of 200–280 °C, which is a trait highly\ndesired for an electrode material but rather unusual for hybrid inorganic–organic\nthin films. Excellent rate capability is ascertained for the Li-terephthalate\nfilms with no conductive additives required. The electrode performance\ncan be further enhanced by depositing a thin protective LiPON solid-state\nelectrolyte layer on top of Li-terephthalate; this yields highly stable\nstructures with capacity retention of over 97% after 200 charge/discharge\ncycles at 3.2 C.