Charge-clustering induced fast ion conduction in 2LiX-GaF3: A strategy for electrolyte design

Sawankumar V Patel; Valentina Lacivita; Haoyu Liu; Erica Truong; Yongkang Jin; Eric Wang; Lincoln Miara; Ryounghee Kim; Hyeokjo Gwon; Rongfu Zhang; Ivan Hung; Zhehong Gan; Sung-Kyun Jung; Yan-Yan Hu

doi:10.1126/sciadv.adj9930

Charge-clustering induced fast ion conduction in 2LiX-GaF₃: A strategy for electrolyte design

Sci Adv. 2023 Nov 24;9(47):eadj9930. doi: 10.1126/sciadv.adj9930. Epub 2023 Nov 22.

Authors

Sawankumar V Patel^{1

2}, Valentina Lacivita³, Haoyu Liu¹, Erica Truong¹, Yongkang Jin¹, Eric Wang³, Lincoln Miara³, Ryounghee Kim⁴, Hyeokjo Gwon⁴, Rongfu Zhang^{1

2}, Ivan Hung², Zhehong Gan², Sung-Kyun Jung^{4

5}, Yan-Yan Hu^{1

2}

Affiliations

¹ Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
² Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA.
³ Advanced Materials Lab, Samsung Advanced Institute of Technology-America, Samsung Semiconductor Inc., Cambridge, MA 02138, USA.
⁴ Battery Material Lab, Material Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea.
⁵ School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919. Republic of Korea.

Abstract

2LiX-GaF₃ (X = Cl, Br, I) electrolytes offer favorable features for solid-state batteries: mechanical pliability and high conductivities. However, understanding the origin of fast ion transport in 2LiX-GaF₃ has been challenging. The ionic conductivity order of 2LiCl-GaF₃ (3.20 mS/cm) > 2LiBr-GaF₃ (0.84 mS/cm) > 2LiI-GaF₃ (0.03 mS/cm) contradicts binary LiCl (10^-12 S/cm) < LiBr (10^-10 S/cm) < LiI (10^-7 S/cm). Using multinuclear ⁷Li, ⁷¹Ga, ¹⁹F solid-state nuclear magnetic resonance and density functional theory simulations, we found that Ga(F,X)_n polyanions boost Li⁺-ion transport by weakening Li⁺-X^- interactions via charge clustering. In 2LiBr-GaF₃ and 2LiI-GaF₃, Ga-X coordination is reduced with decreased F participation, compared to 2LiCl-GaF₃. These insights will inform electrolyte design based on charge clustering, applicable to various ion conductors. This strategy could prove effective for producing highly conductive multivalent cation conductors such as Ca²⁺ and Mg²⁺, as charge clustering of carboxylates in proteins is found to decrease their binding to Ca²⁺ and Mg²⁺.