Liquid Ga-mediated grain boundary engineering for high ionic conductivity and stability in NASICON-type solid electrolytes for Li-ion batteries

Yen-Lin Chen; Wen-Hsuan Lu; Hsiang-Jung Chen; Yen-Shou Huang; Pei-I Wei; Ying-Da Luo; Han-Yi Chen

doi:10.1016/j.electacta.2026.149587

Liquid Ga-mediated grain boundary engineering for high ionic conductivity and stability in NASICON-type solid electrolytes for Li-ion batteries

Yen-Lin Chen, Wen-Hsuan Lu, Hsiang-Jung Chen, Yen-Shou Huang, Pei-I Wei, Ying-Da Luo Han-Yi Chen

Electrochimica acta, Vol.574, p.149587

20/10/2026

: https://doi.org/10.1016/j.electacta.2026.149587

: WOS:001837783700001

Grain-boundary engineering

Liquid metal gallium

NASICON-type solid electrolyte

Sintering aid

Solid-state lithium-ion batteries

High grain-boundary resistance and microstructural degradation caused by high-temperature sintering remain critical barriers to the advancement of NASICON-type solid electrolytes. In this study, we introduce trace amounts of liquid Ga as a sintering aid to engineer the grain boundaries in Li1.35Ca0.05Al0.25Ti1.7(PO4)3 (LCATP). Synchrotron-based structural and chemical environmental analyses confirm that Ga precisely segregates into the intergranular network, forming an amorphous Ga–O interphase rather than doping the bulk lattice. This unique boundary layer promotes high densification (98.3%), lowers the activation energy (0.228 eV), and enables rapid Li-ion transport (6.17 × 10–4 S cm–1). Moreover, the optimized microstructural integrity effectively prevents premature cell failure. Remarkably, the Ga-engineered solid electrolyte enables symmetric Li//Li cells to cycle stably for nearly 4000 h. When integrated with a LiFePO4 cathode, the full cell demonstrates superior rate capability and robust long-term cycling (91% capacity retention after 250 cycles at 0.5C). This grain-boundary engineering strategy offers a highly scalable pathway for developing durable, solid-state Li batteries.

: Liquid Ga-mediated grain boundary engineering for high ionic conductivity and stability in NASICON-type solid electrolytes for Li-ion batteries
: Yen-Lin Chen - National Tsing Hua University
Wen-Hsuan Lu - National Tsing Hua University
Hsiang-Jung Chen - National Tsing Hua University
Yen-Shou Huang - National Tsing Hua University
Pei-I Wei - Cyntec Co., Ltd., Hsinchu, 300092, Taiwan
Ying-Da Luo - Cyntec Co., Ltd., Hsinchu, 300092, Taiwan
Han-Yi Chen (Corresponding Author) - National Tsing Hua University
: Elsevier Ltd
: 12
: National Science and Technology Council in Taiwan: NSTC 112-2628-E-007-014-MY4 Cyntec Co. Ltd.: NSTC 112-2628-E-007-014-MY4 Featured Areas Research Center Program Ministry of Education (MOE) in Taiwan
This research was supported by the National Science and Technology Council in Taiwan under Project Grant No. NSTC 112-2628-E-007-014-MY4, Cyntec Co. Ltd, and the "High Entropy Materials Center" from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan. Furthermore, the authors would like to acknowledge Dr. Jeng-Lung Chen, Dr. Tsung-Yi Chen, Dr. Yu-Cheng Shao, Dr. Hirofumi Ishii at the National Synchrotron Radiation Research Center (NSRRC), Hsinchu, Taiwan, for their assistance in the measurements of operating synchrotron XAS (beamline TLS 17C1 of NSRRC and BL12B2 of SPring-8 in Japan).
: Journal article
: 20/10/2026
: Electrochimica acta, Vol.574, p.149587
: English