Stable Lithium Deposition Generated from Ceramic-Cross-Linked Gel Polymer Electrolytes for Lithium Anode

Abstract

In this work, a composite gel electrolyte comprising ceramic cross-linker and poly(ethylene oxide) (PEO) matrix is shown to have superior resistance to lithium dendrite growth and be applicable to gel polymer lithium batteries. In contrast to pristine gel electrolyte, these nanocomposite gel electrolytes show good compatibility with liquid electrolytes, wider electrochemical window, and a superior rate and cycling performance. These silica cross-linkers allow the PEO to form the lithium ion pathway and reduce anion mobility. Therefore, the gel not only features lower polarization and interfacial resistance, but also suppresses electrolyte decomposition and lithium corrosion. Further, these nanocomposite gel electrolytes increase the lithium transference number to 0.5, and exhibit superior electrochemical stability up to 5.0 V. Moreover, the lithium cells feature long-term stability and a Coulombic efficiency that can reach 97% after 100 cycles. The SEM image of the lithium metal surface after the cycling test shows that the composite gel electrolyte with 20% silica cross-linker forms a uniform passivation layer on the lithium surface. Accordingly, these features allow this gel polymer electrolyte with ceramic cross-linker to function as a high-performance lithium-ionic conductor and reliable separator for lithium metal batteries.

Design Principles of Functional Polymer Separators for High‐Energy, Metal‐Based Batteries

“…The high surface area of separators and their strong affinity to the electrolyte offer ample opportunities to design novel polymer separators that can interact physically or chemically with the liquid electrolyte to promote the desired efficient mass transport . In addition, the flexibility in selecting the chemistry of many polymer separators has motivated recent efforts aimed at addressing voltage stability of the electrolyte, low cation transference numbers of liquid electrolytes, and the safety issues associated with electrolyte decomposition . The interaction between the polymer separator and the electrolyte is magnified when the polymer can be solvated or swollen in a limited amount of electrolyte to form a so‐called, gel‐like electrolyte .…”

Key Aspects of Lithium Metal Anodes for Lithium Metal Batteries

“…e) SEM image of a Li anode showing uniform Li deposition. Reproduced with permission . Copyright 2016, American Chemical Society.…”

“…As a result, this gel polymer electrolyte showed a significant improvement in the Li transference number and Li ion conductivity with increased degree of salt dissociation. Tsao et al reported using a composite gel polymer electrolyte composed of a ceramic cross‐linker and a poly(ethylene oxide) (PEO) matrix to increase the Li transference number and suppress Li dendrite growth (Figure d). The Li metal anode with this gel polymer electrolyte achieved 97% Coulombic efficiency over 100 cycles without dendrite formation (Figure e).…”

Recent progress in solid-state electrolytes for alkali-ion batteries

“…However, the ceramic-polymer GPEs always cannot keep mechanical property, so improvement to constitute a strong skeleton is essential. Tsao et al [146] presented silica cross-linker to achieve cross-linked polymer, which allow PEO polymer to form the channels for Li-ions. The electrolyte membrane was produced by mixing polyetheramine, bisphenol A diglycidyl ether and silica cross-linker and then soaked in liquid electrolyte to form the GPE.…”

“…For sodium-ion batteries, Gao et al [154] presented a composite gel polymer, the key point was the glass fiber which was utilized to get better mechanical strength. PVDF-HFP was adopted as the polymer host, whose hydrophobic nature of PVDF-HFP is detrimental to the performance of batteries at high current density [146,155]. In this case, hydrophilic polydopamine membrane was selected, by coating the membrane on the surface of PVDF-HFP.…”