Zirconium Trisulfide as a Promising Cathode Material for Li Primary Thermal Batteries

Kyriakos Giagloglou,John T S Irvine,Paul A Connor,Julia L Payne,Richard K B Gover,Christina Crouch

doi:10.1149/2.1351614jes

Abstract

In this work ZrS3 has been synthesized by solid state reaction in a sealed quartz tube and investigated as a candidate cathode material in Li thermal batteries. The structure of ZrS3 before and after cell testing has been studied using powder X-ray diffraction. A new spinel related material, LiZr2S4, has been identified as the product of the electrochemical process, which can be indexed to a = 10.452(8) Å cubic unit cell. The electrochemical properties of the batteries were investigated at 500°C against Li13Si4 by galvanostatic discharge and galvanostatic intermittent titration technique (GITT). In a thermal Li cell at 500°C a single voltage plateau of 1.70 V at a current density of 11 mA/cm2 was achieved with capacity of 357 mA h g−1. Therefore ZrS3 material has some promise as a cathode for Li thermal batteries.

Highlights

Thermal batteries are electrochemical devices that convert chemical energy directly to electrical energy by an electrochemical oxidation-reduction reaction at high temperature utilizing a molten salt electrolyte
ZrS3 was synthesized by a solid state reaction in sealed quartz tube to prevent oxidation of the starting materials. 0.966 g of zirconium (Aldrich,100 mesh) and 1.026 g of sulfur (Alfa Aesar,100 mesh, 99.5%) powders were used
Cathode material characterization.—Zirconium trisulfide was studied by a powder X-Ray diffraction in both reflection and transmission geometry with the data shown in Figures 2a and 2b

Summary

Introduction

Thermal batteries are electrochemical devices that convert chemical energy directly to electrical energy by an electrochemical oxidation-reduction reaction at high temperature utilizing a molten salt electrolyte. Until now thermal batteries use a high melting point lithium alloy (Li13Si4) as the anode, a halide salt eutectic bound in an insulating porous material as the electrolyte, and a 1st row transition metal sulfide as the cathode. During discharge process a phase transition takes place Li13Si4 to Li7Si3 corresponds to 3.66 Li+ / mole of Li – Si and the capacity of this alloy is 485 mA h g−1.2 The most common electrolyte for use in thermal batteries is the lithium chloride – potassium chloride eutectic (LiCl 44.8 wt%–55.2 wt% KCl) with a melting point of ∼354◦C and this requires a minimum of 35 wt% MgO as separator.[3] MS2 sulfides where M is Fe, Ni or Co are the most studied cathodes and they have potentials vs Li13Si4 at around 1.70 V for their first electrochemical transition and have further electrochemical transitions, which eventually ends in complete reduction to the metal.[4]. The compound was fired at 730◦C for 1 week, with a heating and cooling rate of 1◦C min−1 used

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