Demonstration of Transparent All-Solid-State Thin-Film Batteries with Novel Anode Structures = Demonstration of Transparent All-Solid-State Thin-Film Batteries with Novel Anode Structures

다국어 초록 (Multilingual Abstract)

This dissertation presents the systematic technological advancement of fully transparent all-solid-state thin-film batteries through a stepwise approach encompassing transparent anode development, thickness–optical optimization of transparent current collectors and active layers, and structural extension toward next-generation transparent solid-state battery architectures.

First, this work proposes, for the first time, a highly conductive and optically transparent AgxSiON-based anode and thoroughly investigates its characteristics. By precisely controlling the nanoscale dispersion of Ag within an amorphous SiON matrix, a transparent anode capable of stable operation in the 0–1.5 V range was achieved, exhibiting superior electrical conductivity, mechanical robustness, and durability during lithium insertion and extraction compared to existing transparent anode concepts.

Subsequently, the thickness-dependent relationship between optical transmittance and electrical conductivity of TiN transparent current collectors was systematically established by combining Essential Macleod Program (EMP) optical simulations with experimental thin-film deposition. The optical and electrical thicknesses of key thin-film layers—including the AgxSiON anode, TiN anode current collector, LiPON solid electrolyte, LFP cathode, and ITO cathode current collector—were systematically optimized to design a multilayer stack that satisfies both transparency and impedance requirements. This optimized design was subsequently implemented in a fully transparent solid-state thin-film full cell, experimentally validating the fundamental design principles and feasibility of transparent thin-film batteries.

Building upon this optimized transparent battery framework, the study was further extended by applying an oxide–metal–oxide (OMO) multilayer architecture capable of providing both transparency and conductivity without a metallic current collector. Through this approach, a fully transparent all-solid-state thin-film battery was demonstrated for the first time, exhibiting high visible-range transmittance and stable cycling performance.

Overall, this dissertation outlines the holistic design and realization principles of transparent solid-state thin-film batteries through a progressive strategy—from transparent anodes, transparent current collectors, and layer-by-layer optical optimization to current-collector-free architectures—thereby establishing a practical technological foundation for next-generation transparent electronic and wearable devices.

국문 초록 (Abstract)

본 학위논문은 투명 음극 개발, 투명 집전체 및 활성층의 두께·광학 최적화, 그리고 차세대 투명 전고체 박막전지 구조로의 확장을 단계적으로 수행함으로써 완전 투명 전고체 박막전지 기술의 체계적 발전 과정을 제시한다.

우선, 본 연구는 높은 전기전도도와 투명성을 동시에 갖춘 AgxSiON 기반 투명 음극을 최초로 제안하고 그 특성을 규명하였다. Ag의 나노 스케일 분산과 비정질 SiON 매트릭스의 조합을 정밀 제어함으로써, 0–1.5 V 영역에서 안정적인 구동이 가능한 투명 음극을 구현하였으며, 기존 투명 음극 개념 대비 우수한 전기전도도, 기계적 안정성, 리튬 삽입/탈리 과정의 내구성을 확보하였다.

챕터 2에서는 TiN 투명 음극 집전체의 두께–투과도–전기전도도 상관성을 Essential Macleod Program(EMP) 광학 시뮬레이션과 실험적 박막 증착 결과를 결합하여 정량적으로 확립하였다. AgxSiON 음극, TiN 음극집전체, LiPON 고체전해질, LFP 양극, ITO 양극집전체 등 주요 박막층의 광학·전기적 두께 최적화를 수행하고, 투명성과 임피던스를 동시에 만족하는 적층 구조를 설계하였다. 최적화된 구조는 실제 전고체 투명 full cell 제작으로 이어졌으며, 이를 통해 투명 박막 전지의 기본적인 설계 원리와 구현 가능성을 실험적으로 검증하였다.

이후 챕터 3에서는 이러한 기반 기술을 확장하여, 금속 집전체 없이도 투명성과 전도성을 동시에 제공하는 OMO(oxide–metal–oxide) 기반 다층 구조를 적용하였다. 이를 통해 완전 투명 전고체 박막전지를 세계 최초로 실증하였으며, 높은 가시광 투과도와 안정적 사이클 특성을 확인하였다.

본 연구는 투명 음극–투명 집전체–층별 광학 최적화–집전체-프리 구조로 이어지는 단계적 진화 전략을 통해 투명 전고체 박막전지의 설계·구현 원리를 총체적으로 제시하였으며, 차세대 투명 전자소자 및 웨어러블 디바이스에 적용 가능한 실질적 기술 기반을 마련한다.

목차 (Table of Contents)

• Abstract i
• Table of Contents iii
• List of Tables vi
• List of Figures vii
• Chapter 1. Introduction １
• 1.1. Study Background １
• 1.2. Purpose of Research ３
• 1.3. Lithium-ion batteries ６
• 1.4. Thin film batteries ８
• 1.5. Transparent thin film batteries １２
• 1.6. Transparent cathode １４
• 1.7. Transparent electrolyte １７
• Chapter 2. Ag-SiNx composite anode for transparent thin film battery ２１
• 2.1. Introduction ２１
• 2.2. Experimental ２４
• 2.2.1. The Design for Thin-film batteries ２４
• 2.2.1. LiFePO₄ thin films ２５
• 2.2.2. LiPON thin films ２５
• 2.2.3. AgxSiOyN anode thin films ２６
• 2.2.4. Physical and optical Characterization of CCS thin films ２７
• 2.2.5 Coin cell preparation and measurements ２７
• 2.2.6. All-solid-state battery fabrication and measurements ２８
• 2.3. Results and Discussion ２９
• 2.4. Conclusions ４６
• 2.5. References ４８
• Chapter 3. Fully transparent thin film battery with TiN Current collector and Thickness & Transparency control by Essential Macleod Program (EMP) simulation ５１
• 3.1. Introduction ５１
• 3.2. Experimental ５４
• 3.3. Results and Discussion ５６
• 3.4. Conclusion ８１
• 3.5. References ８３
• Chapter 4. Current collector-free transparent thin film battery with Oxide/Metal/Oxide anode ８４
• 4.1. Introduction ８４
• 4.2. Experimental ８６
• 4.2.1. Current collector-free Transaprent TFB Fabrication Process. ８６
• 4.2.2. Physical and Electrochemical Characterization. ８７
• 4.3. Results and Discussion ８８
• 4.3.1. Fabrication of Transparent thin film battery ８８
• 4.3.2. LiFePO4 cathode ９４
• 4.3.3. ZTO/ATC/ZTO multilayer anode ９９
• 4.3.4.Li diffusion in ZTO/ATC/ZTO (ZAZ) multilayer anode １０７
• 4.3.5. Transparent thin film battery １１１
• 4.4. Conclusion １１５
• 4.5. References １１６
• Chapter 5. Overall conclusion １１８
• Abstract in Korean １２１