Synthesis and electrochemical study of CoNi2S4 as a novel cathode material in a primary Li thermal battery

The authors acknowledge support and contribution from AWE Plc for this work, and thank the STFC for neutron diffraction beam-time.In this work CoNi2S4 was investigated as a candidate cathode material for Li thermal batteries. The CoNi2S4 was synthesized by a solid state reaction at 550◦C in a sealed quartz tube. Neutron powder diffraction was utilized to confirm normal spinel structure up to 200◦C, however, there was cation disorder above this temperature. The electrochemical properties of the batteries were investigated at 500◦C by galvanostatic discharge to elucidate the mechanism and the products NiS, Co3S4 and Co9S8 of the discharge mechanism were confirmed using powder X-ray diffraction. CoNi2S4 exhibits two voltage plateaus vs Li13Si4 at 500◦C, one at 1.75 V and the second at 1.50 V. CoNi2S4 has an overall capacity of 318 mA h g−1 from OCV 2.58 V to 1.25 V vs Li13Si4 which is comparable to that of the well-known metal disulfidesPublisher PDFPeer reviewe

Zirconium trisulfide as a promising cathode material for Li primary thermal batteries

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.Publisher PDFPeer reviewe

Transition metal chlorides NiCl2, KNiCl3, Li6VCl8 and Li2MnCl4 as alternative cathode materials in primary Li thermal batteries

Special thanks to AWE Plc for their support and funding for this work. The authors would also like to acknowledge the EPSRC Platform Grant EP/K015540/1 and the Royal Society Wolfson Merit Award WRMA 2012/R2.Transition metal chlorides KNiCl3, Li6VCl8 and Li2MnCl4 were synthesized by solid state reaction in sealed quartz tubes and investigated as candidate cathode materials along with NiCl2 in Li thermal batteries. The structure and morphology were studied and electrochemical properties probed at high temperatures (400°C–500°C) against Li13Si4 by galvanostatic discharge and galvanostatic intermittent titration technique (GITT). All the transition metal chlorides reduced to metal and the products of the discharge mechanism were confirmed by powder X-ray diffraction. NiCl2 was tested at 500°C and a capacity of 360 mAhg−1 was achieved. KNiCl3 was tested at different current densities from 15 mA/cm2 to 75 mA/cm2 and a high voltage profile 2.30V was achieved at 425°C with a capacity of 262 mAhg−1. Li6VCl8 was tested at 500°C and a 1.80V voltage plateau at a current density of 7.5 mA/cm2 was achieved with a capacity of 145 mAhg−1. Li2MnCl4 was tested at the same current density at 400°C and a capacity of 254 mAhg−1 was achieved. These transition metal chlorides exhibit higher voltage against Li13Si4 and, hence, provide more specific power compared to the well-known metal disulfides MS2 (M = Fe, Co, Ni) and may be promising cathode materials for Li thermal batteries.Publisher PDFPeer reviewe

In situ thermal battery discharge using CoS2 as a cathode material

Authors thank AWE and the EPSRC (EP/K015540/1) for funding. JTSI acknowledges a Royal Society Wolfson Research Merit award. We thank the STFC for beam-time.Thermal batteries are an established primary battery technology and the most commonly used cathodes in these batteries are transition metal disulfides MS2 (where M = Co, Ni and Fe). However, understanding the evolution of crystalline phases upon battery discharge has been hindered due to the high temperature operation of these batteries. Here we report an experiment that simultaneously collects powder neutron diffraction and electrochemical data as the battery is discharged. Four regions are observed in the diffraction data and four different cobalt containing phases are observed. Multi-phase Rietveld refinement has been used to monitor the evolution of phases during discharge and this is linked to the battery discharge profile. A new discharge mechanism has been proposed which involves hexagonal CoS instead of Co3S4, and the increase in unit cell parameters on discharge suggests the formation of a sulfur deficient solid solution before transformation to Co9S8. This behavior seems reminiscent of that of NiS2 suggesting that the discharge mechanisms of transition metal disulfides may have more similarities than originally thought.Publisher PDFPeer reviewe

In-situ studies of high temperature thermal batteries : a perspective

Funding: UK Engineering and Physical Sciences Research Council (EP/P007821/1).Here we present a perspective on in-situ studies of high temperature batteries. We focus on a primary battery technology- the thermal battery- which possesses a molten salt electrolyte. We discuss aspects of sample environment design, data collection and will briefly look at some case studies. We aim to highlight the importance of using in-situ techniques in studying electrochemical devices such as high temperature batteries.Publisher PDFPeer reviewe

The identification and down selection of suitable cathode materials for use in next generation thermal batteries

In this work new novel cathode materials such as transition-metal sulfides, chlorides or fluorides were investigated and studied for their use in lithium ion thermal batteries. All cathodes were synthesized by a solid state reaction in sealed quartz tubes with a duration of firing for 1 week at high temperatures (> 500 °C). All structures of compounds were probed by powder X-ray diffraction and the morphology and shape of crystallites of cathodes were characterized by scanning electron microscopy. The electrochemical properties of the batteries were investigated by galvanostatic discharge and galvanostatic intermittent titration technique at high temperatures (> 400 °C). All the batteries used as an anode Li₁₃Si₄, as an electrolyte LiCl-KCl eutectic and as separator MgO. All the products of the discharge mechanism were confirmed using powder X-ray diffraction and EDX analysis. CoNi₂S₄ and NiCo₂S₄ exhibit two voltage plateaux vs Li₁₃Si₄ at 500 °C, one at around 1.75 V and the second at 1.50 V. Capacities of 350 and 290 mA h g⁻¹ were achieved, respectively. NiS, Co₃S₄ and Co₉S₈ were confirmed as the products of discharge mechanism. ZrS₃ exhibits a single flat voltage plateau of 1.70 V at a current density of 11 mA/cm² and a capacity of 357 mA h g⁻¹, at 500 °C was obtained. A new material, LiZr₂S₄, was identified as the product of the electrochemical process, which can be indexed to a = 10.452(8) Å cubic unit cell. KNiCl₃ was tested at different current densities from 15 mA/cm² to 75 mA/cm² and a high cell voltage, with a capacity of 262 mA h g⁻¹ was achieved at 425 °C. Ni metal, KCl and LiCl were confirmed as the products of the discharge mechanism. Li₂MnCl₄ was tested at the same current densities as KNiCl₃ at 400 °C and a capacity of 254 mA h g⁻¹ was achieved. Mn metal and LiCl were confirmed as the products after discharge. Li₆VCl₈ has a capacity of 145 mA h g⁻¹ and a flat voltage plateau of 1.80 V at 500 °C. NiCl₂ has also a capacity of 360 mA h g⁻¹ and a high voltage profile of 2.25 V at 500 °C. CoCl₂ exhibits a lower capacity of 332 mA h g⁻¹ and lower voltage profile compared to NiCl₂ at 500 °C. CuF₂ and PbF₂ were tested at 500 °C. PbF₂ exhibits a single flat voltage plateau of 1.25 V and a capacity of 260 mA h g⁻¹ was obtained. CuF₂ has a high voltage profile but a voltage plateau could not be obtained.Funded by AWE Plc

Reversible perovskite electrocatalysts for oxygen reduction/oxygen evolution

The identification of electrocatalysts mediating both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are prerequisite for the development of reversible fuel cells and rechargeable metal–air batteries. The question remains as to whether a bifunctional catalyst, or a single catalyst site, will exhibit potentials converging to +1.23 VRHE. Transition metal-based perovskites provide tunable catalysts where site substitution can influence both ORR and OER, however substitution in the pseudobinary phases results in an anti-correlation in ORR and OER activities. We reveal that LaxMnyNi1-yO3-δ, compositions with lanthanum A-site sub-stoichiometry exhibit reversible activity correlating with the appearance of the Mn3+/Mn4+ redox couple. The Mn3+/Mn4+ couple is associated with Mn4+ co-existing with Mn3+ in the bulk, as La3+ is substituted by Ni2+ at the A-site to create a mixed valent system. We also show that a direct A-site substitution by the Ca2+ cation in LaxCa1-xMnyO3-δ perovskites also results in the creation of Mn4+, the appearance of the Mn3+/Mn4+ redox couple, and a concomitant reversible activity. These results highlight a general strategy of optimizing oxide electrocatalysts with reversible activity

Data underpinning In-situ Thermal Battery Discharge Using CoS2 as a Cathode Material

The data files are not yet publicly available. Enquiries and requests for data should be directed to the publication's corresponding authors: Payne, J. L., Percival, J. D., Giagloglou, K., Crouch, C., Carins, G. M., Smith, R., Gover, R. & Irvine, J. T. S., 2 Aug 2019, In : Journal of The Electrochemical Society. 166, 12, p. A2660-A2664 5 p

Data underpinning - In-Situ Thermal Battery Discharge using NiS2 as a Cathode Material

Diffraction dat