Mass Transfer Performance of Porous Nickel Manufactured by Lost Carbonate Sintering Process

Abstract

Open cell porous metals are excellent electrode materials due to their unique electrochemical properties. However, very little research has been conducted to date on the mass transport of porous metals manufactured by the space holder methods, which have distinctive porous structures. This paper measures the mass transfer coefficient of porous nickel manufactured by the Lost Carbonate Sintering process. For porous nickel samples with a porosity of 0.55-0.75 and a pore size of 250-1500 mm measured at an electrolyte flow velocity of 1-12 cm s À1 , the mass transfer coefficient is in the range of 0.0007-0.014 cm s À1 , which is up to seven times higher than that of a solid nickel plate electrode. The mass transfer coefficient increases with pore size but decreases with porosity. The porous nickel has Sherwood numbers considerably higher than the other nickel electrodes reported in the literature, due to its high real surface area and its tortuous porous structure, which promotes turbulent flow.

Three-dimensional porous metal electrodes: Fabrication, characterisation and use

“…Common open-foam electrodes (Ni, SS, Ti, Cu, and Al) are generally made via casting, electroless deposition of metal coatings on polyurethane precursors or powder metallurgy [9]. Recent work has considered lost carbonate sintering for Ni [10], instead of the usual electroless method. All of these techniques result in randomly organised pores.…”

“…Mass transfer studies for flow-through foam electrodes have been attempted in beaker cells with a recirculating electrolyte [10] and anodic Fenton oxidations have been studied in aerated batch cells [71]. However, these can be considered only as preliminary steps towards flow cell studies.…”

Solute transport and reaction in porous electrodes at high Schmidt numbers

“…The physical link with microstructural material characteristics and coupled reactive-transport phenomena is still a matter of debate; see e.g. Zhu & Zhao (2017) and Kok et al (2019). The picture that emerges from the latest experimental activities and preliminary theoretical analyses is that the optimum operative condition of a porous electrode, however defined, depends on the specific balance between the mechanisms of mass transport and reaction occurring at the pore scale.…”

Modeling the Transient Effects of Pore-Scale Convection and Redox Reactions in the Pseudo-Steady Limit

“…This trend of Sh variation agrees with experimental observations. 53 Thus, low porosity media are preferred as porous substrates for heterogenous electrochemical reactions over high porosity media on the basis of mass transfer consideration alone. On the contrary, low porosity media possess low hydraulic permeability [54][55][56] and high tortuosity for ion transport.…”