Polymeric ionic liquids (PILs) have stirred up great interest for their potential applications as electrolyte hosts in lithium metal batteries (LMBs) because of their desirable performance. In this work, PIL-based gel polymer electrolytes applied in lithium metal batteries (LMBs) at low–medium temperatures (25 °C, 30 °C and 40 °C) are first reported. A novel imidazolium-tetraalkylammonium-based dicationic polymeric ionic liquid, poly(N,N,N-trimethyl-N-(1-vinlyimidazolium-3-ethyl)-ammonium bis(trifluoromethanesulfonyl)imide) is successfully synthesized, and its structure and purity are confirmed by ¹H NMR, FTIR and elemental analysis. Subsequently, the ternary gel polymer electrolytes are prepared by blending the as-synthesized dicationic PIL as the polymer host with 1,2-dimethyl-3-ethoxyethyl imidazolium bis(trifluoromethanesulfonyl)imide (IM(2o2)11TFSI) ionic liquid and LiTFSI salt in different weight ratios. The PIL-LiTFSI-IM(2o2)11TFSI electrolytes reveal low glass transition temperatures around −54 °C and high thermal stability to about 330 °C. Moreover, the ternary gel polymer electrolytes show good ion conductivity around 10⁻⁴ S cm⁻¹ at low–medium temperatures, high electrochemical stability and good interfacial stability with lithium metal. Particularly, the Li/LiFePO₄ cells assembled with polymer electrolytes at a rate of 0.1 C are able to deliver discharge capacities of about 160 mA h g⁻¹, 140 mA h g⁻¹ and 120 mA h g⁻¹ at 40 °C, 30 °C and 25 °C, respectively, with excellent capacity retention, as well as exhibiting acceptable rate capability. These findings reveal that dicationic PIL-based electrolytes have great potential for use as safe electrolytes in LMBs.

In developing all-solid-state polymer electrolytes for wide operating temperature range lithium metal batteries, an exciting organic ionic plastic crystal, N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (P₁₂FSI), has been introduced into the pyrrolidinium-based polymeric ionic liquid (PIL)/LiTFSI solid system to obtain a novel class of PIL–P₁₂FSI–LiTFSI solid polymer electrolytes (SPEs). Such SPEs reveal flexible mechanical characters, attractive room temperature ionic conductivity above 10⁻⁴ S cm⁻¹, and high thermal and electrochemical stability as well as potential to suppress the lithium dendrite growth. Particularly, Li/LiFePO₄ cells assembled with the as-obtained SPE exhibit high discharge capacity and excellent cycle life over a broad operating temperature range (25–80 °C) and good rate performance. This significant finding indicates that the SPE system obtained in our work has great potential for use in wide operating temperature range lithium metal batteries.

In this work, a new class of high-performance polymeric ionic liquid–silica hybrid ionogel electrolytes (HIGEs) is developed by a nonaqueous sol–gel route, in which LiTFSI–ionic liquid as the ion conducting phase is immobilized with a hybrid pyrrolidinium-based polymeric ionic liquid and silica matrix. The thermal and electrochemical properties of these HIGEs as well as their application in lithium metal batteries (LMBs) are investigated. It is found that HIGEs reveal excellent thermal stability, good room temperature ionic conductivity, high electrochemical stability, a suitable lithium ion transference number, and potential to suppress Li dendrite formation. In particular, Li/LiFePO₄ cells with the as-obtained HIGE at 0.2C rate can deliver a discharge capacity of about 150 mA h g⁻¹ at 25 °C, with excellent capacity retention. Moreover, at 0.5C, 1.0C, and 2.0C, the stable discharge capacities are as high as 138.1 mA h g⁻¹, 120.3 mA h g⁻¹ and 73.8 mA h g⁻¹, respectively. The desirable battery performance can be attributed to the good electrochemical properties of HIGEs and interfacial compatibility between HIGEs and electrodes. These findings show that HIGEs prepared in this work have great potential for application as safe electrolytes in LMBs.

In this work, a peculiar nanostructure of SnO₂/Sn@carbon nanospheres dispersed in the interspaces of a three-dimensional SnO₂/Sn@carbon nanowires network composite (denoted as SnO₂/Sn@C) has been successfully fabricated by a facile strategy and confirmed by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, laser Raman spectroscopy, Brunauer–Emmett–Teller method, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy characterization, illustrating the combination of the nanospheres and the 3-dimensional nanowires network. This architecture effectively withstands the volume change and restricts the agglomeration of SnO₂/Sn during the cycling process. Moreover, the SnO₂/Sn distributed in carbon matrix and the SnO₂/Sn@carbon nanospheres dispersed in interspaces of three-dimensional SnO₂/Sn@carbon nanowires network facilitate electron and ion transport throughout the electrode. As a result, this composite exhibits excellent performance as a potential anode material for lithium ion batteries and delivers a reversible capacity of 678.6 mA h g⁻¹ at 800 mA g⁻¹, even after 500 cycles.

The as-prepared SnO₂@DSC exhibits excellent electrochemical performance due to the double-shelled support and confined void strategy.