Compliant glass–polymer hybrid single ion-conducting electrolytes for lithium batteries

Abstract

Despite high ionic conductivities, current inorganic solid electrolytes cannot be used in lithium batteries because of a lack of compliance and adhesion to active particles in battery electrodes as they are discharged and charged. We have successfully developed a compliant, nonflammable, hybrid single ion-conducting electrolyte comprising inorganic sulfide glass particles covalently bonded to a perfluoropolyether polymer. The hybrid with 23 wt% perfluoropolyether exhibits low shear modulus relative to neat glass electrolytes, ionic conductivity of 10 −4 S/cm at room temperature, a cation transference number close to unity, and an electrochemical stability window up to 5 V relative to Li + /Li. X-ray absorption spectroscopy indicates that the hybrid electrolyte limits lithium polysulfide dissolution and is, thus, ideally suited for Li-S cells. Our work opens a previously unidentified route for developing compliant solid electrolytes that will address the challenges of lithium batteries.hybrid electrolytes | inorganic sulfide glasses | fluorinated polymers | lithium batteries | lithium-sulfur batteries E lectrolytes used in lithium ion batteries that power personal electronic devices and electric vehicles comprise lithium salts dissolved in flammable organic liquids. Catastrophic battery failure often begins with the electrolyte decomposition and combustion. In addition, side reactions between the electrolyte and anode particles result in steady capacity fade. Some of the byproducts of side reactions can dissolve in the electrolyte and migrate from one electrode to the other. This effect is minimized in the case of solid electrolytes because of limited solubility and slow diffusion (1). Mixtures of liquids and salts have additional limitations. The passage of current results in an accumulation of salt in the vicinity of one electrode and depletion close to the other electrode, because only the cation participates in the electrochemical reactions. Both overconcentrated and depleted electrolytes have lower conductivity, which accentuates cell polarization and reduces power capability. Concentration polarization is absent in single-ion conductors, wherein the anions are immobilized (2). Nonflammable, single ionconducting solid electrolytes have the potential to dramatically improve safety and performance of lithium batteries (3-6).Solid electrolytes, such as inorganic sulfide glasses (Li 2 S-P 2 S 5 ), are single-ion conductors with high shear moduli (18-25 GPa) and high ionic conductivity (over 10 −4 S/cm) at room temperature (7,8). However, these materials, on their own, cannot serve as efficient electrolytes, because they cannot adhere to moving boundaries of the active particles in the battery electrode as they are charged and discharged. Hayashi et al. (9) prepared hybrid electrolytes by mixing sulfide glasses and poly(ethylene oxide) (PEO) polymers. Although the addition of PEO improves mechanical flexibility, there is a dramatic decrease in ionic conductivity because of the insulative nature of PEO. For exampl...

A new composite solid electrolyte PEO/Li10GeP2S12/SN for all-solid-state lithium battery

“…The results identify that, comparing to those complicated preparation process and high cost methods as mentioned above, the electrochemical stability window of PEO 18 -LiTFSI can be broadened greatly by adding a small amount of 1%LGPS and 10%SN in this work via a convenient method with low cost. This is attribute to there exists ÀSH groups in the surface of LGPS inorganic particles [41]. The groups of ÀSH are very beneficial for promoting the bonding of TFSI À and LGPS, which results in a decrease in the mobility of the anions and this is consistent with the t Li+ as summarized in Table 3.…”

A Single‐Ion Conducting Borate Network Polymer as a Viable Quasi‐Solid Electrolyte for Lithium Metal Batteries

“…To verify adhesion of ANP‐5 over the course of battery cycling and electrode expansion and contraction, we performed storage ( G ′) and loss ( G ″) shear moduli tests at 25 °C on crosslinked and non‐crosslinked membrane electrolytes with 30 wt% plasticizer (Figure 3d). For both materials, G ′ was higher than G ″ by nearly an order of magnitude over the measured frequency range, and both moduli were largely frequency independent, suggesting that the membranes act as elastic solids . The shear modulus of the crosslinked membrane was found to be an order of magnitude larger than that of the non‐crosslinked membrane (0.1 vs 0.01 MPa), confirming that crosslinking improves the membrane mechanical properties.…”

Liquid Sulfur Impregnation of Microporous Carbon Accelerated by Nanoscale Interfacial Effects

“…The assumption is that micro-or mesoporous carbon are sufficient to (1) permit the entry of molten (or sublimed) sulfur when fabricating cathodes and electrolyte during operation but (2) prevent or significantly hinder the escape of polysulfides based on size 20 or unfavorable chemical interactions. 21 Maximizing the performance of porous carbon/sulfur composite cathodes depends on a nanoscale appreciation of which regions naturally favor sulfur accumulation and whether this is of benefit to electrochemical function. This in turn demands selective probes of the buried functional interface with nanometer resolution in order to reveal molecular details of critical energy conversion processes.…”