Improving Cycling Stability of the Lithium Anode by a Spin-Coated High-Purity Li3PS4 Artificial SEI Layer

In situ construction of robust artificial solid-electrolyte interphase layer on lithium-metal anode by a facile one-step solution route

Development of high energy density lithium-metal batteries (LMBs) is markedly hindered by the interfacial instability on lithium-metal anode side. Solid-electrolyte interphase (SEI) is a fundamental factor to regulate dendrite growth and enhance the stability of lithium-metal anodes. Here, trithiocyanuric acid, a triazine derivative with sulfhydryl groups, is used as an efficient promoter to favor the construction of a robust artificial SEI layer on the lithium metal surface, which greatly benefits the stability and efficiency of LMBs. With the assistance of trithiocyanuric acid facilely introduced on the Li surface via a one-step solution route, a highly uniform artificial SEI layer rich in Li2S and Li3N is formed, which efficiently facilitates uniform lithium deposition and suppresses lithium dendrite growth. Remarkably, the Li|Li cell displays stable lithium plating/stripping cycling over 800 h at 0.5 mA cm-2, 1 mAh cm-2, and the Li|LFP cells exhibit prolonged lifespan over 700 cycles at 3 C and superior rate performance from 2 to 20 C. This work provides a facile design strategy for constructing a superb artificial SEI layer for high-performance LMBs.

Spray-Printed Flexible Li2S Cathode with Inorganic Ion-Conductive Binder Nano-Li3PS4

Flexible solid-state batteries fabricated by printing techniques are promising integrated power supplies for miniaturized and customized electronic devices. While typically these batteries use polymer solid electrolytes, a flexible Li2S cathode with sulfide solid electrolyte is spray-printed in this work, by using solvated Li3PS4 nanoparticles as inorganic ion-conductive binder. This benefits from a novel low-temperature-sintering property of these nanoparticles, which can be pressure-free densified, along with the desolvation process, and thus bind the cathode at 250 °C. The battery can be stably charged and discharged for 300 cycles with no stacking pressure, and the capacity maintains at 840 mA h gLi2 S-1. We believe this low-temperature-sintering phenomenon of solid electrolyte nanoparticles will open a new path toward the application of sulfide solid electrolytes in printed solid-state batteries.

A Dual Functional Artificial SEI Layer Based on a Facile Surface Chemistry for Stable Lithium Metal Anode

Solid electrolyte interphase (SEI) on a Li anode is critical to the interface stability and cycle life of Li metal batteries. On the one hand, components of SEI with the passivation effect can effectively hinder the interfacial side reactions to promote long-term cycling stability. On the other hand, SEI species that exhibit the active site effect can reduce the Li nucleation barrier and guide Li deposition homogeneously. However, strategies that only focus on a separated effect make it difficult to realize an ideal overall performance of a Li anode. Herein, a dual functional artificial SEI layer simultaneously combining the passivation effect and the active site effect is proposed and constructed via a facial surface chemistry method. Simultaneously, the formed LiF component effectively passivates the anode/electrolyte interface and contributes to the long-term stable cycling performance, while the Li-Mg solid solution alloy with the active site effect promotes the transmission of Li+ and guides homogeneous Li deposition with a low energy barrier. Benefiting from these advantages, the Li||Li cell with the modified anode performs with a lower nucleation overpotential of 2.3 mV, and an ultralong cycling lifetime of over 2000 h at the current density of 1 mA cm−2, while the Li||LiFePO4 full battery maintains a capacity retention of 84.6% at rate of 1 C after 300 cycles.