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Single-ion polymer electrolytes (SIPEs) with high Li-ion transference number (t Li +≈1) are promising candidates for inhibiting the growth of lithium dendrites in lithium metal batteries (LMBs). However, it remains challenging to develop SIPEs applicable to high-performance LMBs due to their relatively low ionic conductivity and poor mechanical strength. Herein, an aromatic single-ion conductor (LiPSBI) with high Li-ion concentration is elaborately designed, yielding porous and mechanically robust SIPE membranes (NSIPM) when mixed with aliphatic poly (vinylidene fluoride-hexafluoropropylene) P(VDF-HFP) binder via "structural self-assembly" method. As expected, the as-prepared NSIPM porous membranes can simultaneously exhibit a high porosity of 41.4%, a considerable organic solvent uptake of 181.0%, and excellent mechanical strength of 20.5 MPa. Notably, the LiPSBI-based gel NSIPM demonstrates an ionic conductivity of 8.15 × 10−5 S cm−1 at 25 °C, which is almost twice that of the single-ion electrolyte with low Li-ion concentration (4.74 × 10−5 S cm−1). Consequently, the Li||LiFePO 4 cells using the gel NSIPM display remarkable cycling durability for several hundred cycles while delivering high discharge specific capacities of 148.4 mA h g−1 and 122.9 mA h g−1 at 0.2C and 1 C, respectively. In addition, the Li/Li symmetric cells assembling the gel NSIPM can effectively alleviate concentration polarization and inhibit the lithium dendrites growth, which is responsible for an exceptionally steady striping/plating process with a low overpotential over 1300 h at 2.5 mA cm−1 at 25 °C. This work provides a new strategy to prepare high-performance SIPEs by increasing the concentration of charge carriers. [Display omitted] • A new single-ion conductor containing high Li-ion concentration is well-designed. • The SIPE-based porous membranes are prepared via structural self-assembly method. • Ionic conductivity and mechanical strength of the gel SIPEs are highly improved. • Li.||LiFePO 4 cells with the gel SIPEs run stably at 1 C for 1000 cycles at 25 °C [ABSTRACT FROM AUTHOR]

[Display omitted] • A new siloxane-type single-ion conductor was successfully synthesized. • The composite SPEs were prepared by in-situ sol–gel and solution casting methods. • The composite SPEs show enhanced electrochemical and thermal performances. • LiFePO 4 /Li batteries with the SPEs display superior rate and cycling properties. Solid polymer electrolytes (SPEs) significantly improve the operational safety of lithium-metal batteries (LMBs) by replacing the flammable liquid electrolytes, but still suffer from key limitations including low ionic conductivities, inferior lithium-ion transference numbers (t L i + ), and poor mechanical properties. Herein, a novel poly (ethylene oxide) (PEO)-based composite electrolyte, with a semi-interpenetrating polymer network, is fabricated via in-situ cross-linking siloxane-type single-ion conductors (SICs) in PEO SPEs by one-step sol–gel method, enabling they simultaneously achieve the enhanced electrochemical and physicochemical properties. Incorporating a thermodynamically compatible SIC network not only reduces the crystallization of PEO matrix while facilitating the segmental relaxation of polymer chains, but also contributes to dissociating Li-salt and forming a three-dimensional conducting network for fast Li-ion transport. Thus, the resulting composite SPEs exhibit higher ionic conductivities (1.10 × 10−5 S cm−1 at 25 °C and 1.41 × 10−4 S cm−1 at 60 °C), t L i + (0.52), and electrochemical window stability (4. 59 V) than pure PEO SPEs. Furthermore, this stable SIC networks can also enhance the mechanical performance and thermal stability of the composite SPEs. Thanks to these merits, the composite SPEs show the significant feasibility to regulate Li deposition and suppress the growth of Li dendrites, affording excellent stability and compatibility with Li metal. As a result, the Li/Li symmetrical cells using the composite SPEs show excellent cycling performances without an evident polarization enlargement for more than 900 h. The LiFePO 4 /Li batteries also achieve a remarkable capacity of 132.8 mA g−1 at 1C and exhibit impressive cycling abilities with 91.9% retention over 250 cycles. This study provides a promising concept for developing advanced composite SPEs for potential application in solid-state dendrite-free LMBs. [ABSTRACT FROM AUTHOR]

High-temperature-resistant polymer electrolyte membranes with satisfactory Li-ion transference number (t L i + ) and ionic conductivity is desirable for the application in safe and dendrite-proof lithium metal batteries (LMBs). In this study, siloxane-based single-ion conducting polymer electrolyte (SIPE) membranes with high porosity are fabricated by in-situ sol-gel and non-solvent induced phase separation methods. Benefiting from the well-designed three-dimensional interpenetrating polymer network, the thermal and dimensional ability of the as-developed membranes are significantly enhanced. In addition, the porous structure enabling a high liquid electrolyte uptake (468.6%) combines with the intrinsic nature of SIPE for the membranes, giving rise to much higher ionic conductivity of 1.72 × 10−3 S cm−1 and t L i + of 0.72 compared to commercial polypropylene (PP) separators (3.56 × 10−4 S cm−1 and 0.33) at 25 °C. Such excellent electrochemical properties are beneficial to inhibiting the Li dendrites and impeding short-circuiting of batteries. As expected, the Li/Li symmetrical cells show a stable galvanostatic Li plating/stripping cycling performance with a low overpotential of more than 400 h at 2 mA cm−2. Remarkably, the LiFePO 4 /Li batteries using the membranes exhibit impressive rate capacity and superior cycling ability compared to the batteries assembled with PP separators. This novel design and exciting results offer tremendous potential in the construction of dendrite-free LMBs with high safety. [Display omitted] • A novel siloxane-based single-ion conductor was successfully synthesized. • The SIPE porous membranes were prepared by in-situ sol-gel and NIPS techniques. • The porous membranes exhibit superior electrochemical and thermal performances. • LiFePO 4 /Li batteries using the membranes show good rate and cycling properties. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) are promising candidates for constructing the safety and high-performance of lithium metal batteries (LMBs). However, a number of obstacles have limited its further application, such as low ionic conductivity, undesired mechanical properties, and low lithium-ion transference number (t Li + ). Herein, a hydroxyl-rich single conductor polymer (lithium sulfonated polyvinyl alcohol, SPVA-Li) was introduced as a polymeric filler into PEO SPEs network via a simple and scalable solution casting method to fabricate the composite SPEs. The hydrogen bond interactions between SPVA-Li and PEO enable the polymer chains to be more disordered that effectively suppress PEO crystallization, endowing the SPVA-Li SPEs with high ionic conductivity (1.76 × 10−4 S cm−1) and t Li + (0.59) at 60 °C. Moreover, such cross-linking structures also can significantly improve the mechanical strength and thermal stability of the SPVA-Li SPEs. These performances are all superior to the PEO SPEs. Thus, based on the composite SPEs, Li/Li symmetric cells run for 400 h without any short circuits, and the LiFePO 4 /Li batteries also can be stably operated for 100 cycles at 0.2 and 0.5 C rates, respectively. These merits enable the SPVA-Li SPEs to be very promising for developing high-performance LMBs. [Display omitted] • SPVA-Li is introduced as a novel polymeric filler into PEO SPEs matrix. • Crystallization of composite SPEs is significantly decreased by hydrogen bond interactions between SPVA-Li and PEO. • Mechanical properties and electrochemical performances of composite SPEs are simultaneously enhanced. • The LiFePO 4 /Li batteries with the composite SPEs show excellent rate and cycling performance. [ABSTRACT FROM AUTHOR]

• The oxyethyl containing poly(ionic liquids) modified graphene oxide nanoparticles (ox -PIL@GO) was prepared. • The ox -PIL@GO was added into PEO matrix for preparing the PEO/LiTFSI/ ox -PIL@GO composite electrolyte. • The expected multri-interactions among PEO/LiTFSI/ ox -PIL@GO electrolyte give rise to the improved properties. • Toward ambient temperature operation with high coulombic efficiency was successfully obtained. Endowing polyethylene oxide (PEO)-based electrolyte with low crystallinity and high efficient Li+ transport channels is urgently required for next generation all-solid-state lithium metal batteries (LMBs). Herein, a new type of oxyethyl containing poly(ionic liquid) modified graphene oxide nanoparticles (ox -PIL@GO) is coincidentally proposed for preparing PEO based organic–inorganic composite electrolyte membranes (CPEs). Both experimental and DFT simulation results indicate that the dissociation of the LiTFSI is significantly enhanced by the anticipated electrostatic interaction between imidazolium cation and TFSI- anions in CPEs. In addition, the formed electrostatic interaction can also inhibit the movement of TFSI-, giving rise to the increased lithium transference number of 0.61 from 0.21 for the neat PEO/LiTFSI electrolyte. Furthermore, the ion–dipole interaction between imidazolium cation and PEO chain largely reduces the crystallinity of PEO and the ionic conductivity of 1.01 × 10-4 S cm−1 at 40 °C is successfully obtained. As a result, the ox -PIL@GO incorporated PEO electrolyte enables the Li||Li symmetric cell with long-term, square-wave galvanostatic cycling test of 800 h at current density of 0.1 mA cm−2 at 50 °C and the solid-state LiFePO 4 |CPE|Li battery with high discharge specific capacity of 116 mAh g−1 at 40 °C at 1C for 300 cycles. [ABSTRACT FROM AUTHOR]

High-performance gel polymer electrolytes (GPEs) with fire-resistant properties are highly desirable for lithium ion batteries (LIBs) with enhanced safety. Herein, we report a novel GPE derived from a porous poly(ionic liquid)/P(VDF-HFP) (PIL/P(VDF-HFP)) composite membrane prepared via a simple and scalable phase inversion method. The ion-dipole interactions between the PIL and P(VDF-HFP) endow the PIL/P(VDF-HFP) membrane with significantly enhanced mechanical performances and thermal stability. Flexible GPEs can be obtained after absorption of the liquid electrolytes into the PIL/P(VDF-HFP) membrane. The PIL/P(VDF-HFP) GPE exhibits a much higher ionic conductivity (1.78 × 10−3 S cm−1) compared to the liquid electrolytes absorbed in the commercial Celgard 2325 separator (3.5 × 10−4 S cm−1). The Li/LiFePO 4 battery assembled with the GPE exhibits a high reversible capacity of 99.2 mAh g−1 at 12C and high discharge capacities of 138.4 and 125.4 mAh g−1 after 200 charge-discharge cycles at 1C and 4C, respectively. These performances are all superior to the Li/LiFePO 4 battery using the commercial Celgard 2325 separator saturated with liquid electrolytes. Importantly, the PIL/P(VDF-HFP) GPE exhibits excellent fire-resistance, benefiting from the non-flammable property of the PIL. The as-developed GPE shows great potential for the practical application in LIBs with superior electrochemical performances and high safety. Image 1 • New, simple, scalable method to fabricate gel polymer electrolytes for LIBs. • Gel polymer electrolytes with fire-resistance and high ionic conductivity. • Outstanding C-rate capabilities and cycling performances of the LIBs. [ABSTRACT FROM AUTHOR]

Single-ion conducting polymer electrolytes (SIPEs) are promising separator/electrolyte materials in lithium metal batteries (LMBs) owing to their high lithium-ion transference numbers. However, the low ion conductivity and poor interfacial compatibility limit their practical application. The effective structural design and the highly porous membrane preparation are of significance for surmounting above issues. Here, a high-performance fire-resistant phosphine based SIPE with semi-interpenetrating polymer network is designed and its highly porous electrospun nanofiber membrane (nf -sIPN-PECB) is subsequently prepared. After interpenetrated by 1 M LiPF 6 in EC/PC electrolyte, the nf -sIPN-PECB/1M LiPF 6 in EC/DMC electrolyte delivers ultrahigh ion conductivity of 2.5 mS cm−1 and excellent interfacial compatibility for achieving LiFePO 4 cathode LMB with a high discharge capacity of 166 mA h g−1 at 0.1C and 110 mA h g−1 at 6.0C. Moreover, the nf -sIPN-PECB/1M LiPF 6 in EC/DMC electrolyte demonstrates a high lithium-ion transference number of 0.64, endowing LMBs with excellent inhabitation of lithium dendrite growth. Therefore, ultra-long lifespan of 1000 cycles for the LMBs with ignorable capacity decay was successfully achieved. Furthermore, the good fire-retardant, high thermal dimensional stability and excellent flexibility drag LMBs out of severe safety hazards. A high-performance fire-resistant phosphine based SIPE (Li-PECB) with semi-interpenetrating polymer network is well-designed for simultaneously achieving the excellent fire-retardancy, good mechanical strength and enhanced ionic conductivity of the highly porous electrospun nanofiber membrane (nf -sIPN-PECB). The molecular-scale mixture between PVDF-HFP binder and Li-PECB is successfully approached during in-situ polymerization process. [Display omitted] • 3D IPNs of highly porous electrospun nanofiber membrane was prepared. • The porous electrospun nanofiber membrane displays enhanced mechanical strength due to 3D IPNs. • The nf -sIPN-PECB display uniform morphology and molecular level dispersion of components. • The enhanced lithium ion transference number was obtained for suppress lithium dendrite growth. • The promising elevated temperature cell performance with high coulombic efficiency was successfully obtained. [ABSTRACT FROM AUTHOR]