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On the Development of Intercalation-Based Cathode Materials for All-Solid-State Fluoride Ion Batteries

Nowroozi, Mohammad Ali (2020):
On the Development of Intercalation-Based Cathode Materials for All-Solid-State Fluoride Ion Batteries.
Darmstadt, Technische Universität Darmstadt,
DOI: 10.25534/tuprints-00011523,
[Ph.D. Thesis]

Abstract

Recently reversible batteries based on fluoride ions as a charge carriers have attracted some attentions as an alternative electrochemical energy storage system to conventional lithium ion batteries (LIBs). Fluoride is the most stable anion with a high mobility and therefore, fluoride ion batteries (FIBs) can theoretically provide a wide electrochemical potential window. Moreover, FIBs are capable of being built in an all solid-state modification. Previously, electrochemical fluoride ion cells based on conversion-based electrode materials have been built. However, the state of the art of the FIBs suffer from poor cycling performance in lack of well-developed cell components including the electrode materials. In the current study, intercalation-based cathode materials have been investigated as an alternative approach to make electrode materials for FIBs. In this respect, various compounds with mainly Ruddlesden-Popper-type structure including LaSrMO4 (M = Mn, Co, Fe) and La2MO4+d (M = Co, Ni) as well as Schafarzikite-type compounds of Fe0.5M0.5Sb2O4 (M = Mg, Co) have been subjected to electrochemical measurements including galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy and the structural changes upon electrochemical fluorination/de-fluorination were analyzed by X-ray Diffraction (XRD). LaSrMnO4 has been fluorinated/de-fluorinated via electrochemical method confirming successful intercalation/de-intercalation of the fluoride ions, but showed problems for long-term operation. In contrast, La2NiO4+d showed to be the most promising intercalation-based cathode material (for FIB) in terms of cycling stability (>220 cycles and 60 cycles for cutoff capacities of 30 and 50 mAh/g, respectivly) with a nearly 100% Coulombic efficiency (average Coulombic efficiency of 97.68% and 95.44% for cutoff capacities of 30 and 50 mAh/g, respectively). This is the highest cycle life that has been reported so far for a FIB. One of the major challenges of the proposed FIB systems was found in avoiding oxidation of the conductive carbon which has been mixed with the electrodes to improve the electronic conductivity. This decomposition of the carbon matrix results in a remarkable increase in the impedance of the cell and can significantly impair the cycle life and discharge capacity. However, the critical charging conditions which could be determined by cyclic voltammetry and electrochemical impedance spectroscopy have a major impact on preserving the conductivity of the cell. In addition, the effect of volume change in the conversion-based anode materials has been studied showing that the overpotentials arising from the volume change can significantly influence the cycling behavior of the battery system (due to absence of well-developed intercalation-based anode materials for FIBs, conversion-based counter electrodes have been used as anode materials).

Item Type: Ph.D. Thesis
Erschienen: 2020
Creators: Nowroozi, Mohammad Ali
Title: On the Development of Intercalation-Based Cathode Materials for All-Solid-State Fluoride Ion Batteries
Language: English
Abstract:

Recently reversible batteries based on fluoride ions as a charge carriers have attracted some attentions as an alternative electrochemical energy storage system to conventional lithium ion batteries (LIBs). Fluoride is the most stable anion with a high mobility and therefore, fluoride ion batteries (FIBs) can theoretically provide a wide electrochemical potential window. Moreover, FIBs are capable of being built in an all solid-state modification. Previously, electrochemical fluoride ion cells based on conversion-based electrode materials have been built. However, the state of the art of the FIBs suffer from poor cycling performance in lack of well-developed cell components including the electrode materials. In the current study, intercalation-based cathode materials have been investigated as an alternative approach to make electrode materials for FIBs. In this respect, various compounds with mainly Ruddlesden-Popper-type structure including LaSrMO4 (M = Mn, Co, Fe) and La2MO4+d (M = Co, Ni) as well as Schafarzikite-type compounds of Fe0.5M0.5Sb2O4 (M = Mg, Co) have been subjected to electrochemical measurements including galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy and the structural changes upon electrochemical fluorination/de-fluorination were analyzed by X-ray Diffraction (XRD). LaSrMnO4 has been fluorinated/de-fluorinated via electrochemical method confirming successful intercalation/de-intercalation of the fluoride ions, but showed problems for long-term operation. In contrast, La2NiO4+d showed to be the most promising intercalation-based cathode material (for FIB) in terms of cycling stability (>220 cycles and 60 cycles for cutoff capacities of 30 and 50 mAh/g, respectivly) with a nearly 100% Coulombic efficiency (average Coulombic efficiency of 97.68% and 95.44% for cutoff capacities of 30 and 50 mAh/g, respectively). This is the highest cycle life that has been reported so far for a FIB. One of the major challenges of the proposed FIB systems was found in avoiding oxidation of the conductive carbon which has been mixed with the electrodes to improve the electronic conductivity. This decomposition of the carbon matrix results in a remarkable increase in the impedance of the cell and can significantly impair the cycle life and discharge capacity. However, the critical charging conditions which could be determined by cyclic voltammetry and electrochemical impedance spectroscopy have a major impact on preserving the conductivity of the cell. In addition, the effect of volume change in the conversion-based anode materials has been studied showing that the overpotentials arising from the volume change can significantly influence the cycling behavior of the battery system (due to absence of well-developed intercalation-based anode materials for FIBs, conversion-based counter electrodes have been used as anode materials).

Place of Publication: Darmstadt
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Fachgebiet Materialdesign durch Synthese
Date Deposited: 29 Mar 2020 19:55
DOI: 10.25534/tuprints-00011523
Official URL: https://tuprints.ulb.tu-darmstadt.de/11523
URN: urn:nbn:de:tuda-tuprints-115233
Referees: Clemens, Prof. Dr. Oliver and Fichtner, Prof. Dr. Maximilian
Refereed / Verteidigung / mdl. Prüfung: 24 February 2020
Alternative Abstract:
Alternative abstract Language
In den letzten Jahren haben reversible Batterien auf der Basis von Fluorid-Ionen als Ladungsträger als alternatives elektrochemisches Energiespeichersystem zu herkömmlichen Lithium-Ionen-Batterien (LIBs) hohe Aufmerksamkeit erlangt. Fluorid ist das stabilste Anion mit einer hohen Mobilität; daher kann in Fluoridionenbatterien (FIBen) theoretisch ein breites elektrochemisches Potenzialfenster erschlossen werden. Außerdem können FIBen als reine Feststoffbatterien assembliert werden. Bisher wurden elektrochemische Fluorid-Ionen-Zellen auf der Basis von Elektrodenmaterialien auf Konversionsbasis gebaut. Dieses Funktionsprinzip leidet jedoch unter einer geringen Zyklierbarkeit, wobei es zudem an gut entwickelten Zellkomponenten einschließlich der Elektrodenmaterialien mangelt. In dieser Arbeit wurden Kathodenmaterialien auf Interkalationsbasis als alternativer Ansatz zur Herstellung von Elektrodenmaterialien für FIBen untersucht. Hierbei wurden verschiedene Verbindungen im Ruddlesden-Popper Strukturtyp, einschließlich LaSrMO4 (M = Mn, Co, Fe) und La2MO4+d (M = Co, Ni) sowie Verbindungen des Schafarzikit-Typs Fe0.5M0.5Sb2O4 (M = Mg, Co) elektrochemischen Messungen einschließlich galvanostatischem Zyklieren, Cyclovoltammetrie und elektrochemischer Impedanzspektroskopie unterzogen. Strukturänderungen im Rahmen der elektrochemischen Fluorierung/Defluorierung wurden mittels Röntgenbeugung (XRD) analysiert. LaSrMnO4 wurde mit dieser elektrochemischen Methode reversibel fluoriert/defluoriert, was die strukturelle Stabilität der Verbindung aufzeigte, jedoch gleichzeitig Probleme für den Langzeitbetrieb aufwies. Im Vergleich dazu erwies sich La2NiO4+d als das vielversprechendste Kathodenmaterial auf Interkalationsbasis aufgrund seiner Zyklenstabilität (>220 Zyklen bzw. ~60 Zyklen für Cutoff-Kapazitäten von 30 bzw. 50 mAh/g), mit einer fast 100%igen Coulomb-Effizienz (durchschnittliche Coulomb-Effizienz von 97,7 % bzw. 95,4 % für Cutoff-Kapazitäten von 30 bzw. 50 mAh/g). Dies stellt die höchste Lebensdauer, die bisher für eine FIB berichtet wurde, dar. Eine der größten Herausforderungen der vorgeschlagenen FIB-Systeme besteht darin, die Oxidation des leitfähigen Kohlenstoff-Additivs zu vermeiden, das im Elektrodenkomposit zur elektrischen Kontaktierung des Aktivmaterials beigemengt ist. Es konnte gezeigt werden, dass diese Zersetzung der Kohlenstoffmatrix zu einer starken Erhöhung der Impedanz der Zelle führt und dadurch die Lebensdauer und erhaltbare Entladekapazität erheblich beeinträchtigen kann. Die kritischen Ladebedingungen, die durch Cyclovoltammetrie und elektrochemische Impedanzspektroskopie bestimmt werden konnten, zeigen einen großen Einfluss auf die Erhaltung der Leitfähigkeit der Zelle. Darüber hinaus wurde die Auswirkung der Volumenänderung der Anodenmaterialien auf Konversionsbasis untersucht, was zeigt, dass die aus der Volumenänderung resultierenden Überpotenziale das Zyklierungsverhalten des Batteriesystems erheblich beeinflussen können.German
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