Intrinsic Solubilization of Lithium Nitrate in Ester Electrolyte by Multivalent Low-Entropy-Penalty Design for Stable Lithium-Metal Batteries.

LiNO3 is a remarkable additive that can dramatically enhance the stability of ether-based electrolytes at lithium metal anodes. However, it has long been constrained by its incompatibility with commercially used ester electrolytes. Herein, we correlated the fundamental role of entropy with the limited LiNO3 solubility and proposed a new low-entropy-penalty design that achieves high intrinsic LiNO3 solubility in ester solvents by employing multivalent linear esters. This strategy is conceptually different from the conventional enthalpic methods that relies on extrinsic high-polarity carriers. In this way, LiNO3 can directly interact with the primary ester solvents and fundamentally alters the electrolyte properties, resulting in substantial improvements in lithium-metal batteries with high Coulombic efficiency and cycling stability. This work illustrates the significance of regulating the solvation entropy for high-performance electrolyte design.

Regulating the Solvation Structure in Polymer Electrolytes for High-Voltage Lithium Metal Batteries.

Solid polymer electrolytes are promising electrolytes for safe and high-energy-density lithium metal batteries. However, traditional ether-based polymer electrolytes are limited by their low lithium-ion conductivity and narrow electrochemical window because of the well-defined and intimated Li+-oxygen binding topologies in the solvation structure. Herein, we proposed a new strategy to reduce the Li+-polymer interaction and strengthen the anion-polymer interaction by combining strong Li+-O (ether) interactions, weak Li+-O (ester) interactions with steric hindrance in polymer electrolytes. In this way, a polymer electrolyte with a high lithium ion transference number (0.80) and anion-rich solvation structure is obtained. This polymer electrolyte possesses a wide electrochemical window (5.5 V versus Li/Li+) and compatibility with both Li metal anode and high-voltage NCM cathode. Li||LiNi0.5Co0.2Mn0.3O2 full cells with middle-high active material areal loading (~7.5 mg cm-2) can stably cycle at 4.5 V. This work provides new insight into the design of polymer electrolytes for high-energy-density lithium metal batteries through the regulation of ion-dipole interactions.

Multivalent Design of Low-Entropy-Penalty Ion-Dipole Interactions for Dynamic Yet Thermostable Supramolecular Networks.

Dynamic supramolecular networks are constantly accompanied by thermal instability. The fundamental reason is most reversible noncovalent bonds quickly decay at elevated temperatures and dissociate below 100 °C. Here, in this paper, we realize a reversible ion-dipole interaction with high-temperature stability exceeding 150 °C. The resultant supramolecular network can simultaneously possess mechanical strength of 1.32 MPa (14.8 times that of pristine material), dynamic self-healing capability, and a stable working temperature of up to 200 °C. From the prolonged characteristic relaxation time of 600 s even at 100 °C, our material represents one of the most thermally stable dynamic supramolecular polymers. These remarkable performances are achieved by using a new multivalent yet low-entropy-penalty molecular design. In this way, the noncovalent bond can reach a high enthalpy while minimizing the entropy-dominated thermal dissociations.

Stable High-Temperature Lithium-Metal Batteries Enabled by Strong Multiple Ion-Dipole Interactions.

Lithium-metal batteries (LMBs) capable of operating stably at high temperature application scenarios are highly desirable. Conventional lithium-ion batteries could only work stably under 60 °C because of the thermal instability of electrolyte at elevated temperature. Here we design and develop a thermal stable electrolyte based on stable solvation structure using multiple ion-dipole interactions. The strong coordination in solvated structure of electrolyte defines the Li deposition behaviour and the evolution of solid electrolyte interphase at high temperature, which is important to achieve high Li Coulombic efficiency and avoid Li dendritic growth. For high mass loading LiFePO4 -Li cells, the cells at 60 °C with conventional electrolyte easily run into failures, but the cells with our electrolyte at 90 °C and 100 °C could cycle more than 120 and 50 cycles respectively. This work provides new insight into electrolyte design and contributes to the development of high temperature LMBs.

A hyperelastic hydrogel with an ultralarge reversible biaxial strain.

Hyperelastic materials exhibit a nonlinear elastic response to large strains, whereas hydrogels typically possess a low elastic range due to the nonuniform cross-linking and limited chain segments among cross-links. We developed a hyperelastic hydrogel that possesses a broader elastic range by introducing a reversible pearl-necklace structure, in which beads are connected by strings. The subnanometric beads can efficiently unfold and refold under cyclic mechanical strains; thus, the hydrogel can rapidly recover after being stretched to an areal strain of more than 10,000%. Additionally, the hydrogel can quickly heal from minor mechanical damages such as needle punctures and cuts. These advancements make our ionic hydrogels ideal for multifunctional pneumatic gripper materials; they simultaneously offer an ultralarge gripping range, self-sensing capabilities, and fast healing abilities.

A large-strain and ultrahigh energy density dielectric elastomer for fast moving soft robot.

Dielectric elastomer actuators (DEAs) with large actuation strain and high energy density are highly desirable for actuating soft robots. However, DEAs usually require high driving electric fields (>100 MV m-1) to achieve high performances due to the low dielectric constant and high stiffness of dielectric elastomers (DEs). Here, we introduce polar fluorinated groups and nanodomains aggregated by long alkyl side chains into DE design, simultaneously endowing DE with a high dielectric constant and desirable modulus. Our DE exhibits a maximum area strain of 253% at a low driving electric field of 46 MV m-1. Notably, it achieves an ultrahigh specific energy of 225 J kg-1 at only|| ||40|| MV m-1, around 6 times higher than natural muscle and twice higher than the state-of-the-art DE. Using our DE, soft robots reach an ultrafast running speed of 20.6 BL s-1, 60 times higher than that of commercial VHB 4910, representing the fastest DEA-driven soft robots ever reported.

Tough, stable and self-healing luminescent perovskite-polymer matrix applicable to all harsh aquatic environments.

Gelatinous underwater invertebrates such as jellyfish have organs that are transparent, luminescent and self-healing, which allow the creatures to navigate, camouflage themselves and, indeed, survive in aquatic environments. Artificial luminescent materials that can mimic such functionality can be used to develop aquatic wearable/stretchable displays and water-resistant devices. Here, a luminescent composite that is simultaneously transparent, tough and can autonomously self-heal in both dry and wet conditions is reported. A tough, self-healable fluorine elastomer with dipole-dipole interactions is synthesized as the polymer matrix. It exhibits excellent compatibility with metal halide perovskite quantum dots. The composite possesses a toughness of 19 MJ m-3, maximum strain of 1300% and capability to autonomously self-heal underwater. Notably, the material can withstand extremely harsh aqueous conditions, such as highly salty, acidic (pH = 1) and basic (pH = 13) environment for more than several months with almost no decay in mechanical performance or optical properties.

Superstretchable, yet stiff, fatigue-resistant ligament-like elastomers.

Ligaments are flexible and stiff tissues around joints to support body movements, showing superior toughness and fatigue-resistance. Such a combination of mechanical properties is rarely seen in synthetic elastomers because stretchability, stiffness, toughness, and fatigue resistance are seemingly incompatible in materials design. Here we resolve this long-standing mismatch through a hierarchical crosslinking design. The obtained elastomer can endure 30,000% stretch and exhibit a Young's modulus of 18 MPa and toughness of 228 MJ m-3, outperforming all the reported synthetic elastomers. Furthermore, the fatigue threshold is as high as 2,682 J m-2, the same order of magnitude as the ligaments (~1,000 J m-2). We reveal that the dynamic double-crosslinking network composed of Li+-O interactions and PMMA nanoaggregates allows for a hierarchical energy dissipation, enabling the elastomers as artificial ligaments in soft robotics.

Green Nanoparticle Scavengers against Oxidative Stress.

The usage of exogenous antioxidant materials to relieve oxidative stress offers an important strategy for the therapy of oxidative stress-induced injuries. However, the fabrication processes toward the antioxidant materials usually require the involvement of extra metal ions and organic agents, as well as sophisticated purification steps, which might cause tremendous environmental stress and induce unpredictable side effects in vivo. To address these issues, herein, we proposed a novel strategy to fabricate green nanoparticles for efficiently modulating oxidative stress, which was facilely prepared from tea polyphenol extracts (originated from green tea) via a green enzymatic polymerization-based chemistry method. The resulting nanoparticles possessed a uniform spherical morphology and good stability in water and biomedium and demonstrated excellent radical scavenging properties. These nanoparticle scavengers could effectively prevent intracellular oxidative damage, accelerate wound recovery, and protect the kidneys from reactive oxygen species damaging in the acute kidney injury model. We hope this work will inspire the further development of more types of green nanoparticles for antioxidant therapies via similar synthetic strategies using green biomass materials.