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The SEM images of (a) pure PMIA membrane; (b) F doped PMIA membrane; (c) 1 % SiO2−F co‐doped PMIA membrane; (d) 2 % SiO2−F co‐doped PMIA membrane; (e) 3 % SiO2−F co‐doped PMIA membrane ; (f) 4 % SiO2−F co‐doped PMIA membrane and (g) 5 % SiO2−F co‐doped PMIA membrane.
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In this study, a novel double‐layer composite separator based on F‐doped poly‐m‐phenyleneisophthalamide (PMIA) and silicon dioxide (SiO2)‐F co‐doped PMIA membrane is designed and prepared by electrospinning technology. And the combination of F‐doped PMIA membrane and SiO2‐F co‐doped PMIA membrane endows the functional separator with exceedingly hig...
Citations
... Electrospinning technology is a mature preparation technology of non-woven fiber separator materials, which has played a very important role in the construction of onedimensional nanostructured materials. Numerous studies have reported that this kind of technology is used for the preparation of lithium-ion battery separators [87], fuel cell separators, and other porous separator materials. Yin Hu et al. (Figure 10(A)) [88] prepared a nanofiber separator using electrospinning and chemically crosslinked poly(glycol)diacrylate grafted siloxane and polyacrylonitrile aqueous solution. ...
Lithium–sulfur batteries (LSBs) are recognized as one of the second-generation electrochemical energy storage systems with the most potential due to their high theoretical specific capacity of the sulfur cathode (1675 mAhg−1), abundant elemental sulfur energy storage, low price, and green friendliness. However, the shuttle effect of polysulfides results in the passivation of the lithium metal anode, resulting in a decrease in battery capacity, Coulombic efficiency, and cycle stability, which seriously restricts the commercialization of LSBs. Starting from the separator layer before the positive sulfur cathode and lithium metal anode, introducing a barrier layer for the shuttle of polysulfides is considered an extremely effective research strategy. These research strategies are effective in alleviating the shuttle of polysulfide ions, improving the utilization of active materials, enhancing the battery cycle stability, and prolonging the cycle life. This paper reviews the research progress of the separator functionalization in LSBs in recent years and the research trend of separator functionalization in the future is predicted.
... Poly(mphenyleneisophthalamide) (PMIA) with excellent thermal/mechanical stability has been fabricated into non-woven separators for highperformance batteries, yet its low electrolyte uptake is a critical issue [165]. To address the issue, Deng et al. [166] used the fluorochemicalbased emulsion and SiO 2 nanoparticles to dope with PMIA and fabricated a double-layer composite electrospun separator with a pore size of 0.38 μm. The novel separator with a thickness of 50 ± 2 μm showed improved electrolyte uptake and lower contact resistance. ...
High energy density batteries with lithium metal as the anode have been considered the most promising next-generation storage devices applied in electric vehicles, large-scale energy storage stations and so on. However, the promising high-performance has been usually blocked by challenging interface/interphase issues at different levels inside the electrochemical cell. To address the above challenges, polymer-based interface/interphase engineering with rational structure design and flexible processing methods has been proved a very effective way. In this review, we attempt to summarize and discuss the interface/interphase issues from engineering point of view, for the different parts of batteries (cathode, separator, anode). Meanwhile, the reported solutions to these issues via rational design of functional polymers and their processing are summarized accordingly. Particularly, the functional polymer-based interface engineering for addressing the polysulfide diffusion and shuttle effects, structural instability of cathode, and growth of lithium dendrites is emphasized. Furthermore, the significance of the active material microenvironment of the cathode is discussed for a more comprehensive understanding of the interface/interphase issues. Finally, the remaining challenges and perspectives to future efforts are discussed for next-generation high-energy-density batteries.
Due to the extraordinary theoretical energy density, high specific capacity, and environment friendly, lithium-sulfur batteries (LSBs) have been considered as the most promising candidates for energy storage systems. In recent...
Highly porous and conductive microspheres comprising three-dimensionally ordered arrays of mesopores and biphasic iron phosphide (FexP) nanoparticles embedded into nitrogen-doped graphitic carbon (NGC) framework (P-Fex[email protected]) were synthesized by spray pyrolysis method followed by phosphidation. The ordered arrays of mesopores (ϕ = 40 nm) were generated via the thermal breakdown of the polystyrene nanobeads (ϕ = 100 nm). The porous structure not only reduces the effective diffusion length for the charged species but also guarantees efficient electrode wetting along with the accommodation of undesired volume perturbations. The highly conductive NGC framework provides numerous conductive paths for rapid electron transfer, which facilitates kinetically favored redox reactions. Additionally, the polar biphasic FexP nanoparticles allow chemical confinement and catalytic conversion of trapped polysulfides, thus enhancing active material utilization. Correspondingly, the assembled Li–S cells featuring the P-Fex[email protected] separator exhibit good rate performance (350 mA h g⁻¹ at 2.0 C) and extended cycling stability at 0.1, 0.5, and 1.0 C mainly due to high diffusion of charged species (diffusion coefficient (DLi+) = 10⁻⁷ cm² s⁻¹) and low charge transfer resistance. Even at high sulfur loading (3.46 mg cm⁻²) and a low electrolyte/sulfur ratio of 5.6 µL mg⁻¹, the Li−S cells exhibit stable cycling performance.
Although GPE still has the risk of shuttling due to the incomplete removal of liquid electrolytes compared to SPE, which has the most promise of eliminating polysulfide shuttling, researchers have made abundant efforts to eliminate as much of the polysulfide shuttling effect as possible while retaining the unique advantages of GPE. For example, physical barrier to polysulfides by improving the pore size of GPE or fabricating multidimensional structures by different preparation methods. Further chemical adsorption of polysulfides by adding nanofillers to increase polar sites to create polar‐polar interactions with polysulfides or to create Lewis acid‐base interactions. However, although chemical adsorption can indeed highly immobilize polysulfides, it still brings disadvantages such as loss of active material. Therefore, other researchers have employed GPE with ion‐selective permeability that has electrostatic repulsive force or steric hindrance to polysulfides to better inhibit polysulfide shuttling. However, modifying only the cathode side is not enough to enhance this overall properties of Li−S cells. These problems of poor Li⁺ transport, lithium dendrite growth, and poor SEI due to uneven lithium ion deposit on Li anode side still affect the overall performance of Li−S cells. Therefore, a GPE to improve these problems on the Li anode side is summarized below. Compared with an all‐solid electrolyte, GPE, which has a partially liquid electrolyte, clearly has advantages such as strong interfacial contact, good anode interface compatibility, and high flexibility. However, it is still not comparable to the ionic conductivity, etc. of pure liquid electrolyte only. Therefore, the problems on the lithium metal anode side are mainly focused on the lithium ion transport problems and the problems of lithium dendrite growth and inhomogeneous SEI at the lithium anode interface. Facing the problems in these two aspects, researchers have given many improvement solutions respectively. For the lithium ion transport problem, researchers have instead provided pathways for lithium ion transport by adding amorphous nanofibers or nanofillers to reduce the crystallinity of the polymer and improve the ionic conductivity. Alternatively, the migration number of lithium ions can be increased by limiting the anions in the electrolyte. As for the interfacial problems of lithium anodes, researchers have effectively suppressed the growth of lithium dendrites or inhomogeneous lithium plating/stripping phenomena mainly by adding nanofillers to increase the mechanical strength of GPE or by participating in the generation of SEI.
The separator, being an essential component of lithium batteries, has a significant impact on the battery's safety and performance. In recent years, high-performance fibers, which refer to a new generation of synthetic fibers with high strength, high modulus, high temperature resistance, corrosion resistance, flame retardancy, and low density, have been extensively applied as raw or substrate materials in the field of separator for lithium batteries. Therefore, in this review, we begin our analysis by pointing out the shortcomings and issues with currently available commercial polyolefin separators, followed by a summary of the remedies to these issues. Then, we summarize some recently reported high-performance fiber-based separators and a comprehensive analysis is given by highlighting the technologies employed to enhance the safety and/or performance for lithium-ion or lithium-sulfur batteries. Finally, we provide an overview of the future development direction of high-performance fiber-based separators and suggest a few concerns that could be investigated further in this field of research. We hope such a review could shed lights for separator researches dedicated on improving battery safety and performance in the future.
Herein, a special spiderweb-like poly (vinylidene fluoride) (PVDF) gel polymer electrolyte (GPE) including tetrabutylammonium chloride (TBAC) and exposed ZIF-8 nanoparticles was prepared via electrospinning technology. Due to the synergy of TBAC and ZIF-8, the prepared [email protected] ([email protected]) nanofibers were yielded spiderweb-like structure with gel fibers, small pore size, high porosity and uniformly exposed nanoparticles on the surface, thus improving the absorption capacity of the liquid electrolyte. In particular, the uniform distribution of lithium ions above the lithium anode with the limitation of the spiderweb-like structure facilitates uniform lithium deposition and reduces the generation of lithium dendrites. Moreover, the LSBs with [email protected] membranes exhibited high first-cycle discharge capacity of 1324.2 mAh g⁻¹ with extended cycling stability of 0.05% per cycle and Coulombic efficiency of 97% after the 700 cycles at 2 C. The excellent electrochemical and safety properties are attributed to the fact that the gel-like membrane material can not only physically block and chemically adsorb lithium polysulfides (LiPSs), but also greatly inhibit the growth of dendrites. Therefore, the spiderweb-like [email protected] separator can be identified as a dependable candidate for the advanced LSBs.
The practical applications of lithium-sulfur (Li−S) batteries are mainly hindered by the shuttle effect of soluble polysulfides and the slow kinetics of polysulfide conversion. Herein, a multi-component material with cobalt and molybdenum carbide nanoparticles grafted on bamboo-like N-doped carbon nanotubes (Co−Mo2[email protected]) is fabricated and applied to modify the separator to suppress polysulfide migration and to promote polysulfide conversion. The uniformly distributed Co and Mo2C nanoparticles act as both the adsorbent to capture the polysulfides with Co−S and Mo−S bonds by Lewis acid-base interactions and the catalyst to further accelerate the reaction kinetics of polysulfide transformation. Consequently, the Li−S batteries with the Co−Mo2[email protected] separator deliver a high specific capacity of 1324 mAh g⁻¹ at 0.2 C and a capacity decay rate of 0.068 % per cycle at 1 C for 500 cycles. The results suggest the efficient chemical anchoring and catalysis of the multifunctional Co−Mo2[email protected] composite as a feasible method for future large-scale applications of high-performance Li−S batteries.
