Low temperature atomic layer deposition of PbO₂ for electrochemical applications

A low temperature atomic layer deposition (ALD) process for PbO₂ was developed using bis(1-dimethylamino-2-methyl-2-propanolate)lead(II), Pb(DMAMP)₂, and O₃ as the reactants, with a high growth rate of 2.6 Å/cycle. PbO₂ readily reduces under low oxygen partial pressures at moderate temperatures making it challenging to deposit ALD PbO₂ from Pb²⁺ precursors. However, thin films deposited with this process showed small crystalline grains of α-PbO₂ and β-PbO₂, without signs of reduced PbO_x phases. The ALD PbO₂ thin films show the high electrical conductivity characteristic of bulk PbO₂. In situ measurements of ALD PbO₂ film conductivity during growth suggest a reaction mechanism by which sub-surface oxygen mobility contributes to the growth of resistive PbO or PbO_x during the Pb(DMAMP)₂ surface reaction step, which is only fully oxidized from Pb²⁺ to Pb⁴⁺ during the O₃ reaction step. These films were electrochemically reduced to PbSO₄ in H₂SO₄ and then reoxidized to PbO₂, demonstrating their suitability for use as an electrode material for fundamental battery research and other electrochemical applications.. Authors: Bielinski, Ashley R. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000307735782); Emery, Jonathan D. [Northwestern Univ., Evanston, IL (United States)]; Agyapong-Fordjour, Frederick [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000294267894); Jones, Jessica C. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000174754620); Lopes, Pietro Papa [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:000000033211470X). DOE Contract: AC02-06CH11357. Subjects: atomic layer deposition; in situ conductivity; lead acid batteries; lead dioxide