Highly Conductive, Flexible, and Nonflammable Double-Network Poly(ionic liquid)-Based Ionogel Electrolyte for Flexible Lithium-Ion Batteries

Abstract

The solid-state lithium-ion battery is proposed as the ultimate form of battery and has rapidly become an updated attentive research field due to its high safety and extreme temperature tolerance. However, current solid-state electrolytes hardly meet the requirement in practical applications due to its low ionic conductivity, weak mechanical properties, and poor interfacial contact between the electrolyte and the electrode. In this work, we developed a double-network-supported poly­(ionic liquid)-based ionogel electrolyte (DN-Ionogel) via a one-step method. Due to its compact cross-linking structure, the leakage-free DN-Ionogel electrolyte exhibits outstanding flexibility and favorable mechanical properties. In this ionogel electrolyte, the double network favors dissociation of lithium bis­(trifluoromethanesulfony)­imide (LiTFSI), further resulting in remarkable ionic conductivity (1.8 × 10–3 S/cm, room temperature), wide electrochemical window (up to 5.0 V), and high lithium-ion transference number (0.33). Furthermore, the cell (LiFePO4||DN-Ionogel||Lithium) delivers a discharge capacity as high as 150.5 mAh/g, stable cyclic performance (over 200 cycles), and superior rate behavior.

Double‐Network Ionogel Electrolyte with Superior Mechanical Performance and High Safety for Flexible Lithium‐Ion Batteries

“…However, the surface of the lithium metal anode using commercial Celgard membrane soaked with liquid electrolytes conspicuous Li dendrites (Figure S7b). This suggests that the double‐network structures with excellent mechanical performance could suppress the lithium dendrites as well as in previous reports [11c–e,12,14] . Figure 4b displays the rate capability of Li/LiFePO 4 cells with DNIE(200 %)‐20 % electrolyte at various current rates ranging from 0.2 to 2 C. The discharge capacities of Li/LiFePO 4 cells with ionogel(200 %) could reach 146.2, 126.3, 113.2, and 83.2 mAh g −1 at 0.2, 0.5, 1, and 2 C for 10 cycles, respectively.…”

Highly Stretchable, Fast Self-Healing, and Waterproof Fluorinated Copolymer Ionogels with Selectively Enriched Ionic Liquids for Human-Motion Detection

“…Ionic-liquid (IL)-based gels (ionogels) that are made of ILs confined in three-dimensional polymer networks have received substantial attention owing to their unique properties of tailored ionic conductivity, wide operating temperature range, and high thermal/chemical stabilities. , They also have additional merits of mechanical compliance and stretchability through rational structural design, which have shown great potentials in flexible sensors, − energy conversions, , storage devices, , actuators, and so forth. However, conventional ionogels are sensitive to humidity because the polymer matrix and ILs are often hygroscopic, leading to their easy swelling and degradation.…”

Rheological scaling of ionic-liquid-based polyelectrolytes in ionic liquid solutions: the effect of the ion diameter of ionic liquids

“…[11][12][13] The performance of PIL-based materials can be further improved by adding solvents, e.g., ILs, as plasticizers. [14][15][16][17][18][19][20] Consequently, understanding the conformation and the polymer dynamics of PILs in IL solutions is of great importance because they are intimately related to the properties of PIL-based materials.…”

“…, ILs, as plasticizers. 14–20 Consequently, understanding the conformation and the polymer dynamics of PILs in IL solutions is of great importance because they are intimately related to the properties of PIL-based materials.…”