Interface Design Enabling Stable Polymer/Thiophosphate Electrolyte Separators for Dendrite‐Free Lithium Metal Batteries

Abstract

Organic/inorganic interfaces greatly affect Li + transport in composite solid electrolytes (SEs), while SE/ electrode interfacial stability plays a critical role in the cycling performance of solid-state batteries (SSBs). However, incomplete understanding of interfacial (in)stability hinders the practical application of composite SEs in SSBs. Herein, chemical degradation between Li 6 PS 5 Cl (LPSCl) and poly(ethylene glycol) (PEG) is revealed. The high polarity of PEG changes the electronic state and structural bonding of the PS 4 3À tetrahedra, thus triggering a series of side reactions. A substituted terminal group of PEG not only stabilizes the inner interfaces but also extends the electrochemical window of the composite SE. Moreover, a LiF-rich layer can effectively prevent side reactions at the Li/SE interface. The results provide insights into the chemical stability of polymer/sulfide composites and demonstrate an interface design to achieve dendrite-free lithium metal batteries.

Room‐Temperature Solid‐State Polymer Electrolyte in Li‐LiFePO4, Li‐S and Li‐O2 Batteries

“…[14] Recent results demonstrated the crucial role of PEGDME-based polymer electrolytes in stabilizing the electrochemical performance of lithium batteries using layered oxide-based cathodes such as LiNi 0.85 Co 0.1 Mn 0.05 O 2 (NCM). [15] Following this trend, the energy density of the LMB can be remarkably increased by using cathodes with different chemistry rather than the olivinestructured LFP which relies on Li-(de)insertion electrochemical process. [16,17] Li-S and Li-O 2 batteries, based on the Li conversion reaction, have been suggested as the most promising candidates for increasing the energy density of the LMBs to values exceeding 300 W h kg À 1 .…”

“…A similar cell stability and scalability can be achieved at a temperature lower than 60 °C using the same Li‐LFP configuration mentioned above, in which the PEO‐based electrolyte is replaced by a solid poly(ethylene glycol)dimethyl ether (PEGDME) with low molecular weight (e. g.,<5000 Da) for allowing suitable ionic conductivity and operative condition [14] . Recent results demonstrated the crucial role of PEGDME‐based polymer electrolytes in stabilizing the electrochemical performance of lithium batteries using layered oxide‐based cathodes such as LiNi 0.85 Co 0.1 Mn 0.05 O 2 (NCM) [15] . Following this trend, the energy density of the LMB can be remarkably increased by using cathodes with different chemistry rather than the olivine‐structured LFP which relies on Li‐(de)insertion electrochemical process [16,17] .…”

Targeting the Right Metrics for an Efficient Solvent-Free Formulation of PEO:LiTFSI:Li6PS5Cl Hybrid Solid Electrolyte

“…This study underscores the prime importance of optimizing ionic conductivity and mechanical properties concurrently, for successful HSE formulation, and provides valuable insights into key conduction mechanisms. Future research should focus on reducing membrane thickness through particle size control and limiting chemical reactivity, by polymer end group modification or particle protective coating, to match pure ceramic battery performances. Ultimately, we hope that this work serves as a guideline for HSE rational formulation, with emphasis on metric optimization driving further advancements.…”

Boosting the Interfacial Stability of the Li6PS5Cl Electrolyte with a Li Anode via In Situ Formation of a LiF-Rich SEI Layer and a Ductile Sulfide Composite Solid Electrolyte

“…However, the uneven deposition of lithium metal in these systems can result in the formation of hazardous lithium dendrites . These dendrites pose significant safety risks in lithium metal batteries (LMBs) that utilize LEs, including the potential for short circuits, inflammation, and even explosions within the battery. ,, To address this challenge, there is a growing expectation that solid-state electrolytes (SSEs) having high mechanical modulus and exceptional thermal stability will surpass LEs in LMBs, offering superior safety and high energy density. , Due to its prominent characteristics, Li 6 PS 5 Cl (LPSC, Li-argyrodite) has attracted considerable attention among these solid electrolytes (SEs). These include a high ionic conductivity of over 1 mS cm –1 at room temperature, ease of synthesis, and the ability to be processed at low temperatures.…”