A three-dimensional electrochemical model was developed to examine the performance (i.e. impedance determined by a pulse change in potential) of a lithium-ion intercalation positive electrode single particle. A comprehensive parameter study was conducted, based on a layered nickel oxide parameter set previously developed. The dominance of the interfacial impedance on the particle performance accentuates the impact of the secondary particle porosity and electrolyte wetting of the porosity. Electronic distribution effects, including conductivity and particle contacts, also become significant when the secondary particle's effective conductivity is less than about 10(-5) Omega(-1) cm(-1). Most of the simulations were conducted using a spherical shaped secondary particle, but other spheroidal geometries are considered, which only has a marginal impact on particle impedance. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.055303jes] All rights reserved.