Energy harvesting has become a crucial technology for sustainable energy solutions; in particular, the utilization of ambient water movement in hydrovoltaic generators has emerged as a promising approach. However, optimizing performance requires an understanding of structural factors affecting energy harvesting, particularly capillary effects. This study aimed to improve hydrovoltaic generator performance by adjusting internal fiber density, which influences water transport and ion mobility. Using cold isostatic pressing, cellulose acetate (CA) loading in a urethane mold was varied to optimize internal density. As CA loading increased, the fiber arrangement became denser, narrowing capillary pathways and reducing proton mobility. While open-circuit voltage (VOC) remained stable, short-circuit current (ISC) decreased with higher CA mass. The sample with a loading of 0.3 g exhibited the highest energy harvesting efficiency, achieving ISC = 107.2 μA, VOC = 0.15 V, and power (P) = 16.7 μW. This study provides insights into methods of improving hydrovoltaic generator efficiency through internal structural modifications.

1. Introduction
2. Experimental Section
    2.1. 카본 코팅 용액 제조 및 발전기 제작 방법
    2.2. 발전기 성능 평가 및 소재 특성 분석 방법
3. Results and Discussion
    3.1. 수분기반 에너지 하베스팅 메커니즘
    3.2. 발전기 제조를 위한 소재 특성 최적화
    3.3. 발전기 내부 섬유 간 밀도에 의한 하베스팅 성능 최적화
4. Conclusion
Funding
Conflict of Interest
Data Availability Statement
Author Information and Contribution
Acknowledgments
References

• 박지영(한양대학교 재료화학공학과) | Ji Young Park (Department of Materials Science and Chemical Engineering, Hanyang University, Ansan 15588, Republic of Korea)
• 좌용호(한양대학교 재료화학공학과) | Yong-Ho Choa (Department of Materials Science and Chemical Engineering, Hanyang University, Ansan 15588, Republic of Korea) Corresponding author
• 이승환(한국생산기술연구원 국가희소금속센터, 한양대학교 재료화학공학과) | Seung-Hwan Lee (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea, Department of Materials Science and Chemical Engineering, Hanyang University, Ansan 15588, Republic of Korea)
• 백소현(한국생산기술연구원 국가희소금속센터, 한양대학교 재료화학공학과) | So Hyun Baek (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea, Department of Materials Science and Chemical Engineering, Hanyang University, Ansan 15588, Republic of Korea)
• 이현우(한국생산기술연구원 국가희소금속센터) | Hyun-Woo Lee (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea)
• 권용범(한국생산기술연구원 국가희소금속센터) | Yongbum Kwon (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea)
• 이강혁(한국생산기술연구원 국가희소금속센터) | Kanghyuk Lee (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea)
• 박기륭(한국생산기술연구원 국가희소금속센터) | Kee-Ryung Park (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea)
• 송요셉(한국생산기술연구원 국가희소금속센터) | Yoseb Song (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea)
• 김범성(한국생산기술연구원 국가희소금속센터) | Bum Sung Kim (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea)
• 정다운(한국생산기술연구원 국가희소금속센터, 중앙대학교 기계공학부) | Da-Woon Jeong (Korea National Institute of Rare Metals, Korea Institute of Industrial Technology, Incheon 21655, Republic of Korea, School of Mechanical Engineering, Chung-Ang University, Seoul 06974, Republic of Korea) Corresponding author