Sulfide Solid Electrolyte for Lithium/Sulfide All-Solid-State Batteries

All-solid-state lithium batteries are considered as the most promising next generation electrochemical energy storage devices because of their high safety and energy density^[1]. Among all solid electrolytes, sulfide solid electrolytes have attracted increasing attention due to their high ionic conductivities and favorable interface compatibility with sulfur-based cathodes.<br/><br/>In the past decade, different sulfide solid electrolytes with room temperature ionic conductivity of 10^-3 ~ 10^-2 S/cm have been successfully synthesized. The moisture stability can be improved with oxide or halogen doping^[2]. Besides, accroding to process of water molecule adsorption and dissociation reactions, LiF-coated core–shell solid electrolyte can reduce the adsorption site, thus resulting in superior moisture stability when exposing in moist air^[3]. Meanwhile, the interfacial compatibility between solid elctrolyte and lithium anode can also be enhanced. In order to reduce the sulfide solid electrolyte particle size, a liquid/solid fusion technology is developed to synthesize high ionic conductivty sulfide solid electrolyte with reduced particle size^[4]. Based on the high ionic conductive sulfide solid electrolyte powder, thin film can be obtained by cold press solid electrolyte with surface modification^[5], dry film method^[6] and wet coating approach^[7]. The obtained Li_5.4PS_4.4Cl_1.6 sulfide solid electrolyte membrane possesses a high ionic conductivity of 8.4 mS cm^-1 with a thin thickness of 30 μm.^[6] And the thickness of sulfide solid electrolyte film can be further reduced with relative high ionic conductivity above 1 mS cm^-1^[7].<br/><br/>Due to similar chemical potential, sulfide cathodes show excellent interface compatibility with sulfide solid electrolytes. A series of transition metal sulfides or sulfur-based materials are employed as electrodes for all-solid-state rechargeable batteries based on intercalation/deintercalation and conversion reaction mechanisms. Nevertheless, transition metal polysulfides, such as FeS₂^[8], VS₄^[9], and MoS₆^[10], exhibit typical anionic redox driven electrochemical processes. Combination of electronic conductive carbonecious materials and sulfide solid electrolyte coating can realize three-dimensional electronic/ionic conduction networks at the triple solid-solid contact interface. The well-designed transition metal polysulfide MoS₆ nanocomposite delivers a high reversible energy density of 1640 Wh kg^-¹ based on the active material at 0.1 A g^-^1[10].<br/><br/>Although bright prospect of all-solid-state lithium batteries, there are still many challenges for their pratical application. More attentions should be concerned on the high ionic conductivity and high chemical stable sulfide solid electrolytes, reducing the solid electrolyte thickness, electronic/ionic conduction network construction in the electrode layer, high specific areal capacity as well as allievateing stress/strain and volume changes.<br/><br/><b>Reference</b><b>s</b>:<br/>[1] J. Wu, S. Liu, F. Han, et al., <i>Advanced Materials </i>2021, 33, 2000751.<br/>[2] G. Liu, D. Xie, X. Wang, et al., <i>Energy Storage Materials </i>2019, 17, 266.<br/>[3] Y. Jin, Q. He, G. Liu, et al., <i>Advanced Materials </i>2023, 35, 2211047.<br/>[4] H. Wan, J. P. Mwizerwa, F. Han, et al., <i>Nano Energy</i>, 2019, <i>66</i>, 104109.<br/>[5] G. Liu, J. Shi, M. Zhu, et al., <i>Energy Storage Materials </i>2021, 38, 249.<br/>[6] Z. Zhang, L. Wu, D. Zhou, et al., <i>Nano Letters </i>2021, 21 (12), 5233.<br/>[7] X. Zhao, P. Xiang, J. Wu, et al., <i>Nano Letters</i>, 2023, <i>23</i> (1), 227.<br/>[8] H. Wan, G. Liu, Y. Li, et al., <i>ACS Nano </i>2019, 13, 9551.<br/>[9] Q. Zhang, H. Wan, G. Liu, et al., <i>Nano Energy </i>2019, 57, 771.<br/>[10] M. Yang, Y. Yao, M. Chang, et al., <i>Advanced Energy Material</i><i>s</i>, 2023, 13 (28), 2300962.