While imidazolium based chloroaluminate ionic liquids have been studied for decades, with interest increasing over the last several years, phosphonium analogues have received less attention. Recent work has shown phosphonium-based chloroaluminate ionic liquids have significant potential as battery electrolytes due to their high thermal stability and wide electrochemical windows. In order to realize their full potential, fundamental studies on the ion dynamics and transport properties of these systems are required. This work focuses on studying the anion speciation and ion dynamics of a series of acidic chloroaluminates containing phosphonium cations with incrementally varied structures. Their properties are probed through broadband dielectric spectroscopy and oscillatory shear rheology to reveal the frequency and temperature dependence of properties such as conductivity, permittivity, and modulus. We will present preliminary work on the impact of changes in cation structure and ionic liquid composition on anion speciation, transport properties, and dynamics. The results expand our understanding of these important electrolyte systems that hold significant promise for applications such as energy storage, electrodeposition, and chemical synthesis.