Ionogels are considered promising electrolytes for safe lithium‐ion batteries (LIBs) because of their low flammability, good thermal stability, and wide electrochemical stability window. Conventional ionic liquid‐based ionogels, however, face two main challenges; poor mechanical property and low Li‐ion transfer number. In this work, a novel solvate ionogel electrolyte (SIGE) based on an organic–inorganic double network (DN) is designed and fabricated through nonhydrolytic sol–gel reaction and in situ polymerization processes. The unprecedented SIGE possesses high toughness (bearing the deformation under the pressure of 80 MPa without damage), high Li‐ion transfer number of 0.43, and excellent Li‐metal compatibility. As expected, the LiFePO4/Li cell using the newly developed SIGE delivers a high capacity retention of 95.2% over 500 cycles, and the average Coulombic efficiency is as high as 99.8%. Moreover, the Ni‐rich LiNi0.8Co0.1Mn0.1O2 (NCM811)/Li cell based on the modified SIGE achieves a high Coulombic efficiency of 99.4%, which outperforms previous solid/quasi‐solid‐state NCM811‐based LIBs. Interestingly, the SIGE‐based pouch cells are workable under extreme conditions (e.g., severely deforming or clipping into segments). In terms of those unusual features, the as‐obtained SIGE holds great promise for next‐generation flexible and safe energy‐storage devices.
Solid‐state lithium‐ion‐conducting membranes are emerging as a promising electrolyte for rechargeable lithium batteries. However, their reliable and scalable preparation still remain challenges, due to low room‐temperature ionic conductivity of solid polymer electrolytes and inherent brittleness of ceramic inorganic electrolytes. Herein, a simple and cost‐effective morphogenetic route is developed for fabricating hierarchically nanostructured 3D garnet‐type Li7La3Zr2O12 monoliths by using degreasing cotton as a template. Nanostructuring of 3D Li+‐conducting frameworks offers interconnected and continuous Li+‐transport pathways in a poly(ethylene oxide)‐based composite electrolyte. The as‐fabricated solid‐state composite electrolyte is flexible and exhibits an enhanced Li‐ion conductivity of 0.89 × 10−4 S cm−1 as well as a large stable electrochemical window up to 5.5 V versus Li/Li+. The symmetric lithium cell using the 3D‐architectured electrolyte shows good cycling stability at different current densities. Furthermore, the LiFePO4 (+) | hybrid electrolyte | Li (−) battery working at 30 °C exhibits outstanding rate capability and cyclability and delivers a high coulombic efficiency of nearly 100% at a current density of 0.2 C (1 C = 170 mA g−1). The present fabrication route is easy and effective and holds promise for scaled‐up production.
Solid‐state electrolytes that can meet the requirements of high‐safety lithium batteries at high temperature aroused much attention in electrochemical energy storage.Nevertheless, the low ionic conductivity at ambient temperature and poor mechanical strength limit their practical applications. Through unitized configurationdesign, herein, a unique safe and flexible composite polymer electrolyte membrane comprising of inorganic ceramic particles (Li6.75La3Zr1.75Nb0.25O12, LLZNO), polyvinylidene fluoride (PVDF), and lithium perchlorate (LiClO4) are fabricated. Benefitting from the strongly coupled effects via interfacial chemical reactions and the synergistic effects between LLZNOand PVDF, the LLZNO‐based composite electrolyte wetted by ionic liquid exhibits a high ionic conductivity of 1.5 × 10−3 S cm−1 at 25 °C. Moreover, the electrolyte is able to be thermally stable at relatively high temperatures. A LiFePO4 (+) // Li (−) lithium battery using the as‐prepared LLZNO‐based composite electrolyte achieves a good electrochemical stability at ambient temperature, 80 °C and even 120 °C. This work provides an effective way to the fabrication of high‐performance, flexible electrolyte membranes for lithium batteries and other energy‐storage devices that are capable of working over a wide range of temperatures
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