Interface optimization and fast ion exchange route construction in CoS2 electrode by decorated with dielectric Al2O3 nanoparticles for high temperature primary lithium batteries

Abstract

As the most investigated cathode of thermal batteries, the electrochemical performance of CoS 2 is limited by a big polarization at high current density and low working temperature, which is ascribed to the poor wettability of molten salt on CoS 2 surface and low exchange current density. In this contribution, Al 2 O 3 is selected as a modifier to improve the wettability of molten salt on CoS 2 surface and exchange current density at the same time, by adjusting the dielectric polarization field of CoS 2 surface. The discharge capacity (V ≥ 1.7 V) of CoS 2 increases by ~11% at 500 °C with a discharge current of 300 mA cm −2 , and 55% at 450 °C with a discharge current of 100 mA cm −2 , by the decoration of Al 2 O 3 nanoparticles. Moreover, the influence of decorated Al 2 O 3 nanoparticles on the electrochemical performance of CoS 2 are discussed. • CoS 2 decorated with Al 2 O 3 nanoparticles can be synthesized via a simple way. • Optimized interface is able to boost the discharge ability of thermal batteries. • Influence mechanisms of Al 2 O 3 on electrochemical behavior of CoS 2 are studied.