title: Atomic layer deposition of lithium phosphates as solid-state electrolytes for all-solid-state microbatteries.
abstract: Atomic layer deposition (ALD) has been shown as a powerful technique to build three-dimensional (3D) all-solid-state microbattery, because of its unique advantages in fabricating uniform and pinhole-free thin films in 3D structures. The development of solid-state electrolyte by ALD is a crucial step to achieve the fabrication of 3D all-solid-state microbattery by ALD. In this work, lithium phosphate solid-state electrolytes were grown by ALD at four different temperatures (250, 275, 300, and 325 °C) using two precursors (lithium tert-butoxide and trimethylphosphate). A linear dependence of film thickness on ALD cycle number was observed and uniform growth was achieved at all four temperatures. The growth rate was 0.57, 0.66, 0.69, and 0.72 Å/cycle at deposition temperatures of 250, 275, 300, and 325 °C, respectively. Furthermore, x-ray photoelectron spectroscopy confirmed the compositions and chemical structures of lithium phosphates deposited by ALD. Moreover, the lithium phosphate thin films deposited at 300 °C presented the highest ionic conductivity of 1.73 × 10(-8) S cm(-1) at 323 K with ~ 0.51 eV activation energy based on the electrochemical impedance spectroscopy. The ionic conductivity was calculated to be 3.3 × 10(-8) S cm(-1) at 26 °C (299 K).
authors.affiliation: Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9, Canada.
authors.forename: Biqiong
authors.initials: B
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.forename: Qian
authors.initials: Q
authors.lastname: Sun
authors.forename: Ruying
authors.initials: R
authors.lastname: Li
authors.forename: Tsun-Kong
authors.initials: TK
authors.lastname: Sham
authors.forename: Xueliang
authors.initials: X
authors.lastname: Sun