A Review of the Relationship between Gel Polymer Electrolytes and Solid Electrolyte Interfaces in Lithium Metal Batteries

Abstract

Lithium metal batteries (LMBs) are a dazzling star in electrochemical energy storage thanks to their high energy density and low redox potential. However, LMBs have a deadly lithium dendrite problem. Among the various methods for inhibiting lithium dendrites, gel polymer electrolytes (GPEs) possess the advantages of good interfacial compatibility, similar ionic conductivity to liquid electrolytes, and better interfacial tension. In recent years, there have been many reviews of GPEs, but few papers discussed the relationship between GPEs and solid electrolyte interfaces (SEIs). In this review, the mechanisms and advantages of GPEs in inhibiting lithium dendrites are first reviewed. Then, the relationship between GPEs and SEIs is examined. In addition, the effects of GPE preparation methods, plasticizer selections, polymer substrates, and additives on the SEI layer are summarized. Finally, the challenges of using GPEs and SEIs in dendrite suppression are listed and a perspective on GPEs and SEIs is considered.

Recent Progress of Gel Polymer Electrolytes for Sodium Sulfur Batteries

“…GPEs contribute in forming dendrite-free metal anodes by influencing the SEI layer. The design and composition of polymer matrices affect the nature and properties of the SEI layer, such as composition and structure, which are essential for enhancing batteries’ efficiency and stability, hence impacting the interfacial contact between electrolytes and electrodes. − During the charge–discharge process of sodium-based batteries, the plasticizers within the GPEs undergo reactions on the electrode surfaces, resulting in the formation of SEI films, much like in liquid electrolytes. ,, …”

Gel polymer electrolytes for rechargeable batteries toward wide-temperature applications

“…In addition to organic solvents, organic or inorganic metal-ion salts are utilized as functional additives in GPEs for wide-temperature applications, which have a significant impact on the low-temperature and high-temperature performance of electrolytes by altering the degree of dissociation of anions and the ability of SEI formation. 302,331,332 Many salts, such as LiBOB, LiDFOB, and LiPO 2 F 2 , have been investigated as auxiliary additives due to their film-forming ability. 145,333,334 These salts can be sacrificially reduced or oxidized at the anode or cathode surface prior to solvent decomposition, thereby forming low-resistive and stable SEI/ CEI layers composed of inorganic-rich components.…”

“…In addition to organic solvents, organic or inorganic metal-ion salts are utilized as functional additives in GPEs for wide-temperature applications, which have a significant impact on the low-temperature and high-temperature performance of electrolytes by altering the degree of dissociation of anions and the ability of SEI formation. 302,331,332…”

Nitrogen-Doped Carbon Nanothin Film as a Buffer Layer between Anodic Graphite and Solid Electrolyte Interphase for Lithium–Ion Batteries

“…Excess lithium accumulates on the graphite surface during charging and forms a SEI layer, which undergoes a surface oxidation reaction during discharging. The composition of the SEI layer is reported to be strongly influenced by the surface structure of the graphite. , On the basal surface of highly oriented pyrolytic graphite (HOPG), 18.5% of the SEI layer is composed of lithium-based salts, compared to 69.4% on the cross-section of HOPG, 47.5% on soft carbon, and 60.3% on hard carbon. Insoluble lithium-based carbonates are present only on the basal surface of the HOPG and account for 22.8% of the SEI layer .…”