Conformational, thermal, and ionic conductivity behavior of PEO in PEO/PMMA miscible blend: Investigating the effect of lithium salt

2D Ordered Mesoporous Lamellar Hetero-Nanochannels with Asymmetric Wettability for Controllable Ion Transport

Heterogeneous membranes play a crucial role in osmotic energy conversion by effectively reducing concentration polarization. However, most heterogeneous membranes mitigate concentration polarization through an asymmetric charge distribution, resulting in compromised ion selectivity. Herein, hetero-nanochannels with asymmetric wettability composed of 2D mesoporous carbon and graphene oxide are constructed. The asymmetric wettability of the membrane endows it with the ability to suppress the concentration polarization without degrading the ion selectivity, as well as achieving a diode-like ion transport feature. As a result, enhanced osmotic energy harvesting is achieved with a power density of 6.41 W m-2 . This represents a substantial enhancement of 102.80-137.85% when compared to homogeneous 2D membranes, surpassing the performance of the majority of reported 2D membranes. Importantly, the membrane can be further used for high-performance ionic power harvesting by regulating ion transport, exceeding previously reported data by 89.1%.

Bottom-Up Design of a Green and Transient Zinc-Ion Battery with Ultralong Lifespan

Transient batteries are expected to lessen the inherent environmental impact of traditional batteries that rely on toxic and critical raw materials. This work presents the bottom-up design of a fully transient Zn-ion battery (ZIB) made of nontoxic and earth-abundant elements, including a novel hydrogel electrolyte prepared by cross-linking agarose and carboxymethyl cellulose. Facilitated by a high ionic conductivity and a high positive zinc-ion species transference number, the optimized hydrogel electrolyte enables stable cycling of the Zn anode with a lifespan extending over 8500 h for 0.25 mA cm^-2 - 0.25 mAh cm^-2 . On pairing with a biocompatible organic polydopamine-based cathode, the full cell ZIB delivers a capacity of 196 mAh g^-1 after 1000 cycles at a current density of 0.5 A g^-1 and a capacity of 110 mAh g^-1 after 10 000 cycles at a current density of 1 A g^-1 . A transient ZIB with a biodegradable agarose casing displays an open circuit voltage of 1.123 V and provides a specific capacity of 157 mAh g^-1 after 200 cycles at a current density of 50 mA g^-1 . After completing its service life, the battery can disintegrate under composting conditions.

Understanding the effect of liquid crystal content on the phase behavior and mechanical properties of liquid crystal elastomers

Liquid crystal elastomers are stimuli-responsive, shape-shifting materials. They typically require high temperatures for actuation which prohibits their use in many applications, such as biomedical devices. In this work, we demonstrate a simple and general approach to tune the order-to-disorder transition temperature (T_ODT) or nematic-to-isotropic transition temperature (T_NI) of LCEs through variation of the overall liquid crystal mass content. We demonstrate reduction of the T_NI in nematic LCEs through the incorporation of non-mesogenic linkers or the addition of lithium salts, and show that the T_NI varies linearly with liquid crystal mass content over a broad range, approximately 50 °C. We also analyze data from prior reports that include three different mesogens, different network linking chemistries, and different alignment strategies, and show that the linear trend in T_ODT with liquid crystal mass content also holds for these systems. Finally, we demonstrate a simple approach to quantifying the maximum actuation strain through measurement of the soft elastic plateau and demonstrate applications of nematic LCEs with low T_ODTs, including the first body-responsive LCE that curls around a human finger due to body heat, and a fluidic channel that directionally pumps liquid when heated.

A study on the preparation of polycation gel polymer electrolyte for supercapacitors

The polycation gel polymer electrolyte (PGPE) is a promising electrolyte material for supercapacitors due to its high ionic conductivity and great flexibility. Herein, we report a novel flexible PGPE film, which is prepared by thermal copolymerization. The superiority of PGPE is attributed to the existence of charged groups in the polymer skeleton. Consequently, the crystallinity of the polymer is effectively reduced, and the migration of the lithium ion is evidently promoted. Moreover, the liquid retention capacity of the film is improved, which enhances its ionic conductivity as well. The reported PGPE exhibits a high ionic conductivity of 57.6 mS cm-1 at 25 °C and a potential window of 0-1.2 V. The symmetrical PGPE supercapacitor (AC/AC) shows 95.21% mass-specific capacitance retention after 5000 cycles at 2 A g-1 with a maximum energy density of 12.8 W h kg-1 and a maximum power density of 5.475 kW kg-1. This study confirms the exciting potential of PGPE for high performance supercapacitors.

Li2 S6 -Integrated PEO-Based Polymer Electrolytes for All-Solid-State Lithium-Metal Batteries

The integration of Li₂ S₆ within a poly(ethylene oxide) (PEO)-based polymer electrolyte is demonstrated to improve the polymer electrolyte's ionic conductivity because the strong interplay between O^2- _(PEO) and Li⁺ from Li₂ S₆ reduces the crystalline volume within the PEO. The Li/electrolyte interface is stabilized by the in situ formation of an ultra-thin Li₂ S/Li₂ S₂ layer via the reaction between Li₂ S₆ and lithium metal, which increases the ionic transport at the interface and suppresses lithium dendrite growth. A symmetric Li/Li cell with the Li₂ S₆ -integrated composite electrolyte has excellent cyclability and a high critical current density of 0.9 mA cm^-2 at 40 °C. Impressive electrochemical performance is demonstrated with all-solid-state Li/LiFePO₄ and high-voltage Li/LiNi_0.8 Mn_0.1 Co_0.1 O₂ cells at 40 °C.

General and Efficient Synthesis of Two-Dimensional Monolayer Mesoporous Materials with Diverse Framework Compositions

Two-dimensional (2D) mesoporous materials have received substantial research interest due to their highly exposed active sites and unusual nanoconfinement effect. However, controllable and efficient synthesis of 2D mesoporous materials and investigation of their intrinsic properties have remained quite rare. Herein, a general and effective surface-limited cooperative assembly (SLCA) method enabled by leveling precursor solutions on KCl crystals via centrifugation is employed to conveniently synthesize two-dimensional (2D) monolayer mesoporous materials with different compositions. This novel strategy is performed in a manner similar to spin coating, not only enabling generation of ultrathin mesostructured composite film on KCl particles and recycling excessive precursor solution but also providing favorable solvent annealing environment for the film to form ordered mesostructures. Taking monolayer mesoporous Ce_0.8Zr_0.2O₂ solid solutions as a sample, they display ultrathin nanosheet morphology with a thickness of ∼20 nm, highly open porous structure, and easily accessible active sites of surface superoxide species. Upon decoration of 2D mesoporous Ce_0.8Zr_0.2O₂ nanosheets with Pt nanoparticles, the obtained catalyst exhibits superior catalytic activity and stability toward CO oxidation with a low onset temperature of 30 °C and a 100% conversion temperature of 95 °C, which are 35-70 °C lower than those for their counterpart materials, namely, three-dimensional (3D) mesoporous Pt/Ce_0.8Zr_0.2O₂. Moreover, their TOF_Pt value is ∼11.3 times higher than that of 3D mesoporous Pt/Ce_0.8Zr_0.2O₂. Characterizations based on various techniques indicate that such an outstanding catalytic performance is due to the ultrashort distance (20 nm) of mass diffusion, highly exposed active sites, rich surface-chemisorbed oxygen, and the synergistic effect between the Ce_0.8Zr_0.2O₂ matrix and Pt species.

A Universal Lab-on-Salt-Particle Approach to 2D Single-Layer Ordered Mesoporous Materials

The advantages of existing ordered mesoporous materials have not yet been fully realized, due to their limited accessibility of in-pore surface and long mass-diffusion length. A general, controllable, and scalable synthesis of a family of two-dimensional (2D) single-layer ordered mesoporous materials (SOMMs) with completely exposed mesopore channels, significantly improved mass diffusion, and diverse framework composition is reported here. The SOMMs are synthesized via a surface-limited cooperative assembly (SLCA) on water-removable substrates of inorganic salts (e.g., NaCl), combined with vacuum filtration. As a proof of concept, the obtained CeO₂ -based SOMMs show superior catalytic performance in CO oxidation with high conversion efficiency, ≈33 times higher than that of conventional bulk mesoporous CeO₂ . This SLCA is a promising approach for developing next-generation porous materials for various applications.

In Situ Study of Strain-Dependent Ion Conductivity of Stretchable Polyethylene Oxide Electrolyte

There is a strong need in developing stretchable batteries that can accommodate stretchable or irregularly shaped applications including medical implants, wearable devices and stretchable electronics. Stretchable solid polymer electrolytes are ideal candidates for creating fully stretchable lithium ion batteries mainly due to their mechanical and electrochemical stability, thin-film manufacturability and enhanced safety. However, the characteristics of ion conductivity of polymer electrolytes during tensile deformation are not well understood. Here, we investigate the effects of tensile strain on the ion conductivity of thin-film polyethylene oxide (PEO) through an in situ study. The results of this investigation demonstrate that both in-plane and through-plane ion conductivities of PEO undergo steady and linear growths with respect to the tensile strain. The coefficients of strain-dependent ion conductivity enhancement (CSDICE) for in-plane and through-plane conduction were found to be 28.5 and 27.2, respectively. Tensile stress-strain curves and polarization light microscopy (PLM) of the polymer electrolyte film reveal critical insights on the microstructural transformation of stretched PEO and the potential consequences on ionic conductivity.