Li₂S-Based Composite Cathode with in Situ-Generated Li₃PS₄ Electrolyte on Li₂S for Advanced All-Solid-State Lithium–Sulfur Batteries

Abstract

All-solid-state lithium−sulfur batteries (ASSLSBs) are considered to be a promising solution for the next generation of energy storage systems due to their high theoretical energy density and improved safety. However, the practical application of ASSLSBs is hindered by several critical challenges, including the poor electrode/electrolyte interface, sluggish electrochemical kinetics of solid−solid conversion between S and Li 2 S in the cathode, and big volume changes during cycling. Herein, the 85(92Li 2 S-8P 2 S 5 )-15AB composite cathode featuring an integrated structure of a Li 2 S active material and Li 3 PS 4 solid electrolyte is developed by in situ generating a Li 3 PS 4 glassy electrolyte on Li 2 S active materials, resulting from a reaction between Li 2 S and P 2 S 5 . The wellestablished composite cathode structure with an enhanced electrode/electrolyte interfacial contact and highly efficient ion/electron transport networks enables a significant enhancement of redox kinetics and an areal Li 2 S loading for ASSLSBs. The 85(92Li 2 S-8P 2 S 5 )-15AB composite demonstrates superior electrochemical performance, exhibiting 98% high utilization of Li 2 S (1141.7 mAh g (Li2S)−1) with both a high Li 2 S active material content of 44 wt % and corresponding areal loading of 6 mg cm −2 . Moreover, the excellent electrochemical activity can be maintained even at an ultrahigh areal Li 2 S loading of 12 mg cm −2 with a high reversible capacity of 880.3 mAh g −1 , corresponding to an areal capacity of 10.6 mAh cm −2 . This study provides a simple and facile strategy to a rational design for the composite cathode structure achieving fast Li−S reaction kinetics for high-performance ASSLSBs.

Enhanced Cycling Stability of All-Solid-State Lithium–Sulfur Battery through Nonconductive Polar Hosts

“…We think that the gradual capacity increase in pOMS/S70 arose from the increasing contacts between S/Li 2 S and carbon additives/SSEs during volume expansion and contraction in cycling. Similar behaviors have also been reported in other works on ASSLSBs. , Moreover, the insulating nature of SiO 2 also minimized the decomposition of sulfide electrolytes, and the strong bonding between S/Li 2 S and SiO 2 anchored the active materials to avoid detachment from the hosts and the loss of conducting contact. On the contrary, the sulfur utilization in the carbon host would deteriorate at each cycle due to the decomposition of electrolyte and detachment from carbon, resulting in capacity decay.…”

Preparation of Lithium Sulfide-Based Cathode Materials and Application to All-Solid-State Batteries

“…Blending Li 3 PS 4 with Li 2 S in Li-S batteries with an organic electrolyte results in the delithiation of Li 3 PS 4 , which forms a redox mediator that activates Li 2 S, thereby reducing the reaction voltage in the initial cycle 7) . The in situ generation of a Li 3 PS 4 glass electrolyte on Li 2 S active materials also demonstrates Atsunori MATSUDA and Kazuhiro HIKIMA superior electrochemical performance, exhibiting 98% utilization of Li 2 S 8) . Substituting Li in Li 2 S with multivalence cations is expected to form Li vacancies that enhance the electrochemical activity of Li 2 S.…”

Constructing the Interconnected Charge Transfer Pathways in Sulfur Composite Cathode for All-Solid-State Lithium–Sulfur Batteries

“…Unfortunately, the difficulty of forming such triple-phase interfaces poses a significant obstacle to the efficient utilization of sulfur. Additionally, ASSLSBs face the issue of high interfacial resistance because of the solid–solid contacts inherent in all-solid-state battery systems. , Attempts to address the charge conduction and interfacial challenges prompted research on transition metal oxides or sulfides (such as VO 3 , VS 2 , CuO, and MoS 2 ) for their potential utilization as sulfur host materials. − These materials offer simultaneous electrical and ionic conduction pathways to the sulfur and are electrochemically stable in contact with sulfide solid electrolytes. , Notably, 1T-phase MoS 2 , which has metallic properties, can effectively transfer electrons and Li ions to sulfur. , Moreover, MoS 2 has been reported to enhance sulfur conversion kinetics, which has given rise to intensive research on LSBs. , The conduction properties and physical characteristics of MoS 2 vary depending on the synthesis method, leading to diverse morphologies and phases. , …”

“…Additionally, ASSLSBs face the issue of high interfacial resistance because of the solid−solid contacts inherent in allsolid-state battery systems. 14,15 Attempts to address the charge conduction and interfacial challenges prompted research on transition metal oxides or sulfides (such as VO 3 , VS 2 , CuO, and MoS 2 ) for their potential utilization as sulfur host materials. 16−18 These materials offer simultaneous electrical and ionic conduction pathways to the sulfur and are electrochemically stable in contact with sulfide solid electrolytes.…”