DGIST Scholar: New electrode materials by exploratory synthesis for rechargeable Ca-ion batteries

Department of Energy Science and Engineering Theses Ph.D.

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New electrode materials by exploratory synthesis for rechargeable Ca-ion batteries

Title: New electrode materials by exploratory synthesis for rechargeable Ca-ion batteries

Author(s): Hunho Kwak

DGIST Authors: Kim, Jae Hyun ; Kwak, Hunho ; Hong, Seung-Tae

Advisor: 홍승태

Co-Advisor(s): Jae Hyun Kim

Issued Date: 2019

Awarded Date: 2019-08

Type: Thesis

Description: Calcium batteries, Powder X-ray diffraction, Exploratory synthesis, Cell designs, Intercalation

Table Of Contents: 1. Motivation 1
1.1 Why calcium? 1
1.2 Intercalation mechanism in batteries 3
1.3 Exploratory synthesis 4
Reference 10

2. Cell designs for Calcium ion batteries study 12
2.1 Normal test cell called “K-cell.” 12
2.2 K-cell for In-situ bench-top XRD 12
2.3 Temperature-controlled In-situ XRD K-cell 13
2.4 Large-area electrode battery cell for an aqueous system 13
Reference 20

3. Methods and techniques 21
3.1 Methods 21
3.1.1 Testing with already known materials from other ion batteries 21
3.1.2 Exploratory synthesis 22
3.2 Experimental techniques 23
3.2.1 Powder X-ray diffraction techniques 23
3.2.2 Thermal analysis 23
3.2.2 Electrochemical techniques 24
3.2.4 Bond valence sum (BVS) & BVS Mapping (BVSM) 25
3.2.5 Chemical insertion test with CaI2 26
Reference 35

4. Hewettite, CaV6O16⋅6H2O(CVO), as a high-capacity and ultra-stable intercalation host material for calcium-ion storage 36
4.1 Introduction 36
4.2 Synthesis of CVO 38
4.2 Results and discussion 38
4.2.1 Material Characterization 39
4.2.2 Electrochemical Characterization 39
4.2.3 Evidence of Ca intercalation from structural and elemental analysis 40
4.2.4 Bond Valence Sum Maps 41
Reference 55

5. Metahewettite, CaV6O16⋅3H2O, intercalation host material for calcium-ion storage 57
5.1 Introduction 57
5.2 Synthesis of CVO 58
5.3 Results and discussion 58
5.2.1 Material Characterization 58
5.2.2 Electrochemical calcium storage performance 59
5.2.3 Chemically Ca-ion insertion via CaI2 with metahewettite 60
5.2.4 Bond Valence Sum difference maps calculation 60
Reference 70

6. Miscellaneous parts – related to multivalent ions batteries 71
6.1 New materials for multivalent ion intercalation 71
6.1.1 Ca-V-O compounds (CaVO) 71
6.1.2 Al-V-O compounds (AlVO) 71
6.1.3 Cr-V-O compounds (CrVO) 72
6.1.4 Mn-V-O compounds (MnVO) 72
6.1.5 New material for Barium-ion battery: Ba-V-O compounds (BaVO) 73
6.1.6 New material for Strontium-ion battery: Sr-V-O compounds (SrVO) 73
6.1.7 CaMo6S8 synthesis via microwave oven 74
6.2 XRD holder designs for air and moisture sensitive sample 75
6.1.1 XRD holder for Panalytical Empyrean, Empyrean ALPHA-1, and Pohang accelerator 75
6.3 Optical battery test Cell design for observation In-situ metal surface 75

7. Conclusions 77

8. Summary (in Korean) 75