Yang Yu

Bio: Yang Yu is an academic researcher from Shandong University. The author has contributed to research in topics: Self-healing hydrogels & Ionic liquid. The author has an hindex of 6, co-authored 10 publications receiving 107 citations.

Alkaline Double-Network Hydrogels with High Conductivities, Superior Mechanical Performances, and Antifreezing Properties for Solid-State Zinc–Air Batteries

Abstract: For the development of advanced flexible and wearable electronic devices, functional electrolytes with excellent conductivity, temperature tolerance, and desirable mechanical properties need to be engineered. Herein, an alkaline double-network hydrogel with high conductivity and superior mechanical and antifreezing properties is designed and promisingly utilized as the flexible electrolyte in all-solid-state zinc-air batteries. The conductive hydrogel is comprised of covalently cross-linked polyelectrolyte poly(2-acrylamido-2-methylpropanesulfonic acid potassium salt) (PAMPS-K) and interpenetrating methyl cellulose (MC) in the presence of concentrated alkaline solutions. The covalently cross-linked PAMPS-K skeleton and interpenetrating MC chains endow the hydrogel with good mechanical strength, toughness, an extremely rapid self-recovery capability, and an outstanding antifatigue property. Gratifyingly, the entrapment of a concentrated alkaline solution in the hydrogel matrix yields an extremely high ionic conductivity (105 mS cm-1 at 25 °C) and an excellent antifreezing capacity. The hydrogel retains comparable conductivity and eligible strength to withstand various mechanical deformations at -20 °C. The all-solid-state zinc-air batteries using PAMPS-K/MC hydrogels as flexible alkaline electrolytes exhibit comparable values of specific capacity (764.7 mAh g-1), energy capacity (850.2 mWh g-1), cycling stability, and mechanical flexibility. The batteries still possess competitive electrochemical performances even when the operating temperature drops to -20 °C.

Single lithium-ion polymer electrolytes based on poly(ionic liquid)s for lithium-ion batteries.

Abstract: A promising method of synthesizing a lithium-containing room temperature polymeric ionic liquid (PIL) by utilizing the zwitterionic effect to turn a lithium salt into a liquid for single lithium-ion conduction was proposed. In this work, the room temperature PIL was constructed by the equimolar monomer mixture of zwitterion 3-(1-vinyl-3-imidazolic)propanesulfonate (VIPS) and 4-styrenesulfnny(trifluoromethylsulfony)imde (LiSTFSI) based on intermolecular electrostatic interactions. In situ photopolymerization with flexible chain poly(ethylene glycol)methyl ether methacrylate (PEGM) and cross-linker poly(ethylene glycol)dimethacrylate (PEGDM) in the presence of propylene carbonate (PC) generated free-standing PIL electrolyte films. The PIL electrolytes with Li+-rich channels have an excellent lithium transference number approaching unity (0.93 at room temperature) while attaining comparable ionic conductivity (σ ≈ 1.31 × 10−4 S cm−1 at 30 °C). The charge–discharge performance of a Li/LiFePO4 half-cell equipped with this PIL electrolyte would provide a promising model system for novel single lithium ion conductors.

Polyoxometalate-Based Photochromic Supramolecular Hydrogels with Highly Ordered Spherical and Cylindrical Micellar Nanostructures

Abstract: Polyoxometalates (POMs) have attracted much attention in the field of photochromic materials. However, POM-based photochromic supramolecular hydrogels with high transparency and good photochromic properties are seldom reported. In this work, a homogenous, optically transparent, injectable, and photochromic supramolecular hydrogel was fabricated through the coassembly of ammonium heptamolybdate (Mo7 ) and an imidazolium-based zwitterionic amphiphile (3-(1-hexadecyl-3-imidazolio)propanesulfonate (C16 IPS)). The balance between electrostatic attraction and repulsion of Mo7 clusters and zwitterionic amphiphiles enables them to coassemble into a homogenous and transparent supramolecular hydrogel. By adjusting the molar ratio of C16 IPS/Mo7 , ordered spherical micelle-based hydrogels and aligned wormlike micelle-based hydrogels can be obtained. The incorporation of Mo7 into hydrogels endows these hydrogels with excellent photochromic properties. Specifically, after coassembly with C16 IPS, the photochromic ability of hydrogels is significantly enhanced compared with that of a pure aqueous solution of Mo7 . These hydrogels exhibit great potential applications as photochromic materials for the recording of rewritable information.

Engineering Dual Single‐Atom Sites on 2D Ultrathin N‐doped Carbon Nanosheets Attaining Ultra‐Low Temperature Zn‐Air Battery

Abstract: Herein, a novel dual single-atom catalyst comprising adjacent Fe-N4 and Mn-N4 sites on 2D ultrathin N-doped carbon nanosheets with porous structure (FeMn-DSAC) was constructed as the cathode for a flexible low-temperature Zn-air battery (ZAB). FeMn-DSAC exhibits remarkable bifunctional activities for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Control experiments and density functional theory calculations reveal that the catalytic activity arises from the cooperative effect of the Fe/Mn dual-sites aiding *OOH dissociation as well as the porous 2D nanosheet structure promoting active sits exposure and mass transfer during the reaction process. The excellent bifunctional activity of FeMn-DSAC enables the ZAB to operate efficiently at ultra-low temperature of -40 °C, delivering 30 mW cm-2 peak power density and retaining up to 86 % specific capacity from the room temperature counterpart.

Polysulfide Regulation by the Zwitterionic Barrier toward Durable Lithium–Sulfur Batteries

Abstract: Rational regulation on polysulfide behaviors is of great significance in pursuit of reliable solution-based lithium-sulfur (Li-S) battery chemistry. Herein, we develop a unique polymeric zwitterion (PZI) to establish a smart polysulfide regulation in Li-S batteries. The zwitterionic nature of PZI integrates sulfophilicity and lithiophilicity in the matrix, fostering an ionic environment for selective ion transfer through the chemical interactions with lithium polysulfides (LiPS). When implemented as a functional interlayer in the cell configuration, PZI empowers strong obstruction against polysulfide permeation but simultaneously allows fast Li+ conduction, thus contributing to significant shuttle inhibition as well as the resultant facile and stable sulfur electrochemistry. The PZI-based cells realize excellent cyclability over 1000 cycles with a minimum capacity fading rate of 0.012% per cycle and favorable rate capability up to 5 C. Moreover, a high areal capacity retention of 5.3 mAh cm-2 after 300 cycles can be also obtained under raised sulfur loading and limited electrolyte, demonstrating great promise in developing high-efficiency and long-lasting Li-S batteries.