Ionic liquids (ILs) are room-temperature molten salts that possess unique properties, such as negligible vapour pressure, good thermal stability and non-flammability, together with high ionic conductivity and a wide window of electrochemical stability. Combining ILs with polymer electrolytes offers the prospect of new applications e.g. in batteries and fuel cells, where they surpass the performance of conventional media such as organic solvents (in batteries) or water (in polymer electrolyte membrane fuel cells), giving advantages in terms of improved safety and a higher operating temperature range. However, the most important challenge is how to immobilize ILs in polymer matrices while retaining their soughtafter properties. Our goal in this review is to survey the recent developments and issues within IL research in polymer electrolytes.

Polysulfide shuttling and uncontrollable lithium dendrite growth have hampered the application of lithium–sulfur (Li–S) batteries. Although various materials have been utilized to overcome these obstacles, simple and scalable methods are still needed for Li–S battery commercialization. It is shown for the first time that the layer‐by‐layer (LbL) self‐assembly of 2D nanomaterials can be used to controllably fabricate multifunctional separators that simultaneously trap polysulfides and suppress lithium dendrite growth. The double‐sided “nanobrick wall” structure, constructed by MoS2/poly(diallyl dimethyl ammonium chloride) hybrid in conjunction with poly(acrylic acid) (PAA), provides a physical shield against polysulfides and the chemical adsorption of such species by MoS2 and PAA. At the same time, the robust and Li‐ion conducting MoS2 layers strengthen the separator and regulate Li deposition, thereby effectively suppressing Li dendrite formation. As a result, a simple sulfur cathode battery with an ultralight separator coating (0.10 mg cm−2) is able to achieve an outstanding cycle stability with a capacity decay as low as 0.029% per cycle over 2000 cycles and a reversible areal capacity ≈2.0 mAh cm−2 at 1 C. The proposed LbL approach opens the door to the simple, scalable, and economic fabrication of advanced functional separators for use in the real world.

This article reports flexible PEO-based electrolytes with self-healing and highly stretchable properties for lithium-ion batteries.

Developing powerful and reliable strategies to covalently functionalize graphene for efficient grafting and achieving precise interface control remains challenging due to the strong interlayer cohesive energy and the surface inertia of graphene. Here, we present versatile and efficient grafting strategies to functionalize graphene nanosheets. An alkyne-bearing graphene core was used to prepare polymer-functionalized graphene using 'grafting to' and 'grafting from' strategies in combination with reversible chain transfer and click chemistry. The use of the 'grafting to' approach allows full control over limited length grafted polymer chains, while permitting a high grafting density to a single graphene face, resulting in good solubility and processability. The 'grafting from' approach offers complementary advantages, such as the grafting of high molecular weight polymer chains and a better coverage ratio on the graphene surface; however, the extra steps introduced, the presence of initiating groups, and difficulty in controlling the grafted polymer lead to decreased processability. Various types of polymer chains have been successful covalently tethered to graphene nanosheets using these two approaches, producing various molecular brushes with multifunctional arms resulting in watersoluble, oil-soluble, acidic, basic, polar, apolar, and variously functionalized polymers. This work describes versatile methodologies, using the 'grafting to' and 'grafting from' approaches, for the preparation of individually dispersed graphene nanosheets having the desirable properties described.

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Abstract:The relentless increase in the demand for useable power from energy-hungry economies continues to drive energy-material related research. Fuel cells, as a future potential power source that provide clean-at-the-point-of-use power offer many advantages such as high efficiency, high energy density, quiet operation, and environmental friendliness. Critical to the operation of the fuel cell is the proton exchange membrane (polymer electrolyte membrane) responsible for internal proton transport from the anode to the cathode. PEMs have the following requirements: high protonic conductivity, low electronic conductivity, impermeability to fuel gas or liquid, good mechanical toughness in both the dry and hydrated states, and high oxidative and hydrolytic stability in the actual fuel cell environment. Water soluble polymers represent an immensely diverse class of polymers. In this comprehensive review the initial focus is on those members of this group that have attracted publication interest, principally: chitosan, poly (ethylene glycol), poly (vinyl alcohol), poly (vinylpyrrolidone), poly (2-acrylamido-2-methyl-1-propanesulfonic acid) and poly (styrene sulfonic acid). The paper then considers in detail the relationship of structure to functionality in the context of polymer blends and polymer based networks together with the effects of membrane crosslinking on IPN and semi IPN architectures. This is followed by a review of pore-filling and other impregnation approaches. Throughout the paper detailed numerical results are given for comparison to today's state-of-the-art Nafion ® based materials.

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