Kang Hyungu, Roh Heesook, Lee Jongseo, Park Sang-Hyeon, Park Joohyeon, Jeong Heonjae, Yoon Hyun-Ki, Ahn Tae-Young, Choi Yusong
Defense Materials and Energy Development Center, Agency for Defense Development Yuseong P.O. Box 35 Daejeon 34060 South Korea
Department of Electronic Engineering, Gachon University 1342 Seongnam-daero Seongnam Gyeonggi 13120 South Korea.
RSC Adv. 2025 Aug 1;15(33):27345-27355. doi: 10.1039/d5ra03917g. eCollection 2025 Jul 25.
The paradigm shift from conventional molten-salt electrolytes to solid-state garnet-type LiLaZrO (LLZO) electrolytes in thermal batteries represents a critical advancement in high-temperature energy-storage systems. This study evaluated Ta- and Ga-doped LLZO electrolytes for FeS/Li-Si thermal batteries, focusing on their structural stability and electrochemical performance at 500 °C. While Ga-doped LLZO exhibited superior ionic conductivity at 25 °C, Ta-doped LLZO demonstrated exceptional high-temperature stability. Ta-doped LLZO cells achieved longer discharge durations and higher energy densities than Ga-doped LLZO cells, which is attributed to the retained cubic phase and minimised interfacial degradation. Conversely, Ga-doped LLZO exhibited cubic-to-tetragonal phase transitions, Ga precipitation, and formation of impurities such as GaO and Li-Ga alloys, leading to 54% loss of ionic conductivity post-discharge. These results contribute valuable insights for the optimisation of solid-state electrolytes in thermal battery systems, suggesting that conventional room-temperature performance metrics may not translate directly to elevated-temperature operations.
热电池中从传统熔盐电解质到固态石榴石型LiLaZrO（LLZO）电解质的范式转变代表了高温储能系统的一项关键进展。本研究评估了用于FeS/Li-Si热电池的Ta掺杂和Ga掺杂的LLZO电解质，重点关注它们在500°C下的结构稳定性和电化学性能。虽然Ga掺杂的LLZO在25°C时表现出优异的离子电导率，但Ta掺杂的LLZO表现出卓越的高温稳定性。与Ga掺杂的LLZO电池相比，Ta掺杂的LLZO电池实现了更长的放电持续时间和更高的能量密度，这归因于其保留的立方相和最小化的界面降解。相反，Ga掺杂的LLZO表现出立方相到四方相的转变、Ga析出以及诸如GaO和Li-Ga合金等杂质的形成，导致放电后离子电导率损失54%。这些结果为热电池系统中固态电解质的优化提供了有价值的见解，表明传统的室温性能指标可能无法直接转化为高温操作。
