Mixed Ionically/Electronically Conductive Double-Phase Interface Enhanced Solid-State Charge Transfer for a High-Performance All-Solid-State Li–S Battery

Abstract

An all-solid-state lithium–sulfur battery (ASSLSB) is a promising candidate for post-Li-ion battery technologies with high energy densities and good safety performance. However, the intrinsic insulating nature of sulfur requires triple-phase contact with an ionic conductor and an electronic conductor for electrochemical reactions, which decreases the amount of active surface and lowers the charge-transfer efficiency. In this work, a double-phase interface constructed from a mixed ionic/electronic conductor is proposed to enhance the solid-state electrochemical reaction of sulfur. By employing lithium lanthanum titanium oxide/carbon (LLTO/C) nanofibers with mixed ionic/electronic conductivity, enhanced charge-transfer behavior is realized at the sulfur–LLTO/C double-phase interface, compared to the traditional triple-phase interface. As a result, high sulfur utilization and excellent rate performance are achieved. And the facilitated charge transfer shows great potential to lower the operating temperature and improve the sulfur content for practical applications of ASSLSBs. Cycle performance is also enhanced due to the suppressed shuttle effect of polysulfides by the incorporation of the LLTO/C nanofibers.

A Polysulfide-Repulsive, In Situ Solidified Cathode–Electrolyte Interface for High-Performance Lithium–Sulfur Batteries

“…Lithium–sulfur battery, with a high theoretical specific energy of ca. 2600 Wh kg –1 , represents one of the cutting-edge electrochemical energy storage technologies for enabling long-driving-distance electric vehicles. − Currently, the electrochemical energy storage via the Li–S system is impeded by the inferior practical performance of the battery. − Formation and dissolution of Li polysulfide (LiPS) intermediates at the cathode–electrolyte interface (CEI) have been identified as two of the most notorious issues that hinder the stable operation of Li–S batteries. − During the discharge–charge process, the continuous loss of LiPSs from the S particle surface not only depletes active S on the cathode but also increases the salt concentration of the electrolyte and triggers unfavorable parasitic reactions with Li metal that passivate the anode. As a result, the Li–S batteries usually show significant capacity decay upon continuous cycling or raising the discharge–charge rate. − In addition to physically or chemically adsorbing the LiPSs by the cathode host, − solid electrolytes were also proposed to suppress LiPS formation and shuttling and to enable the stable operation of Li–S batteries. − However, most of the solid electrolytes show low bulk Li + conductivity and poor contact with the electrodes, which could hinder charge transfer and result in poor kinetics of the electrode reaction. , In situ creation of a partially solidified electrode–electrolyte interface (mostly the S-electrolyte interface) from one or more liquid electrolyte components has been proven effective in inhibiting LiPS shuttling while maintaining fast charge transfer owing to improved interfacial contact with the S cathode (Table S1).…”

Superior polysulfide adsorption ability by using Ti3C2 nanosheets as effective reservoirs for high electrochemical performance

“…Thus, it is crucial to improve the electronic conductivity and to restrain the polysulfide dissolution and the shuttle effect 8,9 . Aside from this, lithium anodes suffer from severe lithium dendrite growth, which can pierce the traditional PP separator and cause safety problems 10‐12 …”

“…8,9 Aside from this, lithium anodes suffer from severe lithium dendrite growth, which can pierce the traditional PP separator and cause safety problems. [10][11][12] From the above discussion, it can be concluded that the issues causing poor electrochemical performance are complex. 13 Therefore, various methods should be developed for improving the electrochemical performance of lithium-sulfur batteries.…”

Amino‐functionalized SiO 2 modified porous polyetherimide separator for high performance Li‐S batteries

“…5 Aiming at these issues, numerous efforts have been devoted to this area. [6][7][8][9][10][11][12] Of these, separator modification and functionalization provide an attractive solution by virtue of its simplicity and effectiveness. [13][14][15] As an important part of Li-S batteries, the separator prohibits the cutting-out of batteries and acts as the channel to transport lithium ions between electrodes.…”

“…It refers to that in the process of charging and discharging of Li‐S batteries, soluble polysulfide intermediates produced by the cathode pass through the separator, diffuse to the metal lithium anode, and react with metal lithium, thus resulting in the irreversible loss of active material and low coulombic efficiency 5 . Aiming at these issues, numerous efforts have been devoted to this area 6‐12 . Of these, separator modification and functionalization provide an attractive solution by virtue of its simplicity and effectiveness 13‐15 …”