Latent-heat thermophotovoltaic (TPV) batteries offer a pathway for long-duration energy storage, but their scalability is limited by the low thermal conductivity of high-temperature phase change materials (PCMs), which restricts heat extraction during discharge as a solid crust forms. This work presents an idealized theoretical analysis of a TPV battery architecture employing optically transparent PCMs to enable combined conductive and radiative heat transfer through the storage medium. A quasi-one-dimensional model is used to compare opaque PCMs with two idealized transparency scenarios: fully transparent and phase-dependent (transparent solid, opaque liquid). Under the simplifying assumptions of perfect transparency, blackbody emitters, and adiabatic boundaries, the model predicts that transparency can sustain higher emitter temperatures during discharge and increase the average power density by mitigating the thermal resistance of the solid crust. A parametric sensitivity analysis further examines the influence of key PCM properties—including thermal conductivity, refractive index, and effective radiative attenuation—showing that the qualitative performance advantages of transparency persist over a relatively broad parameter range. These conditions relax the conventional trade-off between PCM thickness and power output, establishing an upper bound on the performance improvements that transparency could provide. Since no currently known high-temperature PCM satisfies these ideal transparency assumptions, the results should be interpreted as theoretical limits intended to guide future searches for materials with partial or wavelength-dependent transparency under operating conditions. • Idealized modeling of TPV batteries with high-temperature transparent PCMs • Radiatively transparent PCMs boost emitter temperature and power output. • Transparency alleviates solid-crust bottlenecks during discharge. • Breaks trade-off between energy capacity and power density in storage • Sets upper bounds and motivates search for real high-T transparent PCMs
A. Datas (Thu,) studied this question.