Suspension electrolyte with modified Li+ solvation environment for lithium metal batteries.

Designing a stable solid-electrolyte interphase on a Li anode is imperative to developing reliable Li metal batteries. Herein, we report a suspension electrolyte design that modifies the Li+ solvation environment in liquid electrolytes and creates inorganic-rich solid-electrolyte interphases on Li. Li2O nanoparticles suspended in liquid electrolytes were investigated as a proof of concept. Through theoretical and empirical analyses of Li2O suspension electrolytes, the roles played by Li2O in the liquid electrolyte and solid-electrolyte interphases of the Li anode are elucidated. Also, the suspension electrolyte design is applied in conventional and state-of-the-art high-performance electrolytes to demonstrate its applicability. Based on electrochemical analyses, improved Coulombic efficiency (up to ~99.7%), reduced Li nucleation overpotential, stabilized Li interphases and prolonged cycle life of anode-free cells (~70 cycles at 80% of initial capacity) were achieved with the suspension electrolytes. We expect this design principle and our findings to be expanded into developing electrolytes and solid-electrolyte interphases for Li metal batteries.

Correlating Kinetics to Cyclability Reveals Thermodynamic Origin of Lithium Anode Morphology in Liquid Electrolytes.

The rechargeability of lithium metal batteries strongly depends on the electrolyte. The uniformity of the electroplated Li anode morphology underlies this dependence, so understanding the main drivers of uniform plating is critical for further electrolyte discovery. Here, we correlate electroplating kinetics with cyclability across several classes of electrolytes to reveal the mechanistic influence electrolytes have on morphology. Fast charge-transfer kinetics at fresh Li-electrolyte interfaces correlate well with uniform morphology and cyclability, whereas the resistance of Li+ transport through the solid electrolyte interphase (SEI) weakly correlates with cyclability. These trends contrast with the conventional thought that Li+ transport through the electrolyte or SEI is the main driver of morphological differences between classes of electrolytes. Relating these trends to Li+ solvation, Li nucleation, and the charge-transfer mechanism instead suggests that the Li/Li+ equilibrium potential and the surface energy─thermodynamic factors modulated by the strength of Li+ solvation─underlie electrolyte-dependent trends of Li morphology. Overall, this work provides an insight for discovering functional electrolytes, tuning kinetics in batteries, and explaining why weakly solvating fluorinated electrolytes favor uniform Li plating.

Steric Effect Tuned Ion Solvation Enabling Stable Cycling of High-Voltage Lithium Metal Battery.

1,2-Dimethoxyethane (DME) is a common electrolyte solvent for lithium metal batteries. Various DME-based electrolyte designs have improved long-term cyclability of high-voltage full cells. However, insufficient Coulombic efficiency at the Li anode and poor high-voltage stability remain a challenge for DME electrolytes. Here, we report a molecular design principle that utilizes a steric hindrance effect to tune the solvation structures of Li+ ions. We hypothesized that by substituting the methoxy groups on DME with larger-sized ethoxy groups, the resulting 1,2-diethoxyethane (DEE) should have a weaker solvation ability and consequently more anion-rich inner solvation shells, both of which enhance interfacial stability at the cathode and anode. Experimental and computational evidence indicates such steric-effect-based design leads to an appreciable improvement in electrochemical stability of lithium bis(fluorosulfonyl)imide (LiFSI)/DEE electrolytes. Under stringent full-cell conditions of 4.8 mAh cm-2 NMC811, 50 µm thin Li, and high cutoff voltage at 4.4 V, 4 M LiFSI/DEE enabled 182 cycles until 80% capacity retention while 4 M LiFSI/DME only achieved 94 cycles. This work points out a promising path toward the molecular design of non-fluorinated ether-based electrolyte solvents for practical high-voltage Li metal batteries.

Mild Synthesis of 3,4-Dihydroisoquinolin-1(2H)-ones via Rh(III)-Catalyzed Tandem C-H-Allylation/N-Alkylation Annulation with 2-Methylidenetrimethylene Carbonate.

A tandem rhodium(III)-catalyzed system was established to access 3,4-dihydroisoquinolin-1(2H)-one by coupling of N-methoxy-3-methylbenzamide with 2-methylidenetrimethylene carbonate. This one-pot synthesis protocol processed smoothly under mild reaction conditions. Moreover, a total of 28 examples, broad substrate scope, and high functional-group compatibility were observed. Preliminary mechanism studies were also conducted and demonstrated that the rhodium(III) catalyst played a vital role in the C-H-allylation and N-alkylation cyclization process.

Access to acridones by tandem copper(I)-catalyzed electrophilic amination/Ag(I)-mediated oxidative annulation of anthranils with arylboronic acids.

An efficient and practical approach for the synthesis of medicinally important acridones was developed from anthranils and commercially available arylboronic acids by a tandem copper(I)-catalyzed electrophilic amination/Ag(I)-mediated oxidative annulation strategy. This new and straightforward protocol displayed a broad substrate scope (25 examples) and high functional group tolerance. What's more, a possible mechanistic proposal was also presented.

Stretchable electrochemical energy storage devices.

The increasingly intimate contact between electronics and the human body necessitates the development of stretchable energy storage devices that can conform and adapt to the skin. As such, the development of stretchable batteries and supercapacitors has received significant attention in recent years. This review provides an overview of the general operating principles of batteries and supercapacitors and the requirements to make these devices stretchable. The following sections provide an in-depth analysis of different strategies to convert the conventionally rigid electrochemical energy storage materials into stretchable form factors. Namely, the strategies of strain engineering, rigid island geometry, fiber-like geometry, and intrinsic stretchability are discussed. A wide range of materials are covered for each strategy, including polymers, metals, and ceramics. By comparing the achieved electrochemical performance and strain capability of these different materials strategies, we allow for a side-by-side comparison of the most promising strategies for enabling stretchable electrochemical energy storage. The final section consists of an outlook for future developments and challenges for stretchable supercapacitors and batteries.

A Cation-Tethered Flowable Polymeric Interface for Enabling Stable Deposition of Metallic Lithium.

A fundamental challenge, shared across many energy storage devices, is the complexity of electrochemistry at the electrode-electrolyte interfaces that impacts the Coulombic efficiency, operational rate capability, and lifetime. Specifically, in energy-dense lithium metal batteries, the charging/discharging process results in structural heterogeneities of the metal anode, leading to battery failure by short-circuit and capacity fade. In this work, we take advantage of organic cations with lower reduction potential than lithium to build an electrically responsive polymer interface that not only adapts to morphological perturbations during electrodeposition and stripping but also modulates the lithium ion migration pathways to eliminate surface roughening. We find that this concept can enable prolonging the long-term cycling of a high-voltage lithium metal battery by at least twofold compared to bare lithium metal.

Revealing the Multifunctions of Li3N in the Suspension Electrolyte for Lithium Metal Batteries.

Inorganic-rich solid-electrolyte interphases (SEIs) on Li metal anodes improve the electrochemical performance of Li metal batteries (LMBs). Therefore, a fundamental understanding of the roles played by essential inorganic compounds in SEIs is critical to realizing and developing high-performance LMBs. Among the prevalent SEI inorganic compounds observed for Li metal anodes, Li3N is often found in the SEIs of high-performance LMBs. Herein, we elucidate new features of Li3N by utilizing a suspension electrolyte design that contributes to the improved electrochemical performance of the Li metal anode. Through empirical and computational studies, we show that Li3N guides Li electrodeposition along its surface, creates a weakly solvating environment by decreasing Li+-solvent coordination, induces organic-poor SEI on the Li metal anode, and facilitates Li+ transport in the electrolyte. Importantly, recognizing specific roles of SEI inorganics for Li metal anodes can serve as one of the rational guidelines to design and optimize SEIs through electrolyte engineering for LMBs.

Conducting polymer-based granular hydrogels for injectable 3D cell scaffolds.

Injectable 3D cell scaffolds possessing both electrical conductivity and native tissue-level softness would provide a platform to leverage electric fields to manipulate stem cell behavior. Granular hydrogels, which combine jamming-induced elasticity with repeatable injectability, are versatile materials to easily encapsulate cells to form injectable 3D niches. In this work, we demonstrate that electrically conductive granular hydrogels can be fabricated via a simple method involving fragmentation of a bulk hydrogel made from the conducting polymer PEDOT:PSS. These granular conductors exhibit excellent shear-thinning and self-healing behavior, as well as record-high electrical conductivity for an injectable 3D scaffold material (~10 S m-1). Their granular microstructure also enables them to easily encapsulate induced pluripotent stem cell (iPSC)-derived neural progenitor cells, which were viable for at least 5 days within the injectable gel matrices. Finally, we demonstrate gel biocompatibility with minimal observed inflammatory response when injected into a rodent brain.

An Electrochemical Gelation Method for Patterning Conductive PEDOT:PSS Hydrogels.

Due to their high water content and macroscopic connectivity, hydrogels made from the conducting polymer PEDOT:PSS are a promising platform from which to fabricate a wide range of porous conductive materials that are increasingly of interest in applications as varied as bioelectronics, regenerative medicine, and energy storage. Despite the promising properties of PEDOT:PSS-based porous materials, the ability to pattern PEDOT:PSS hydrogels is still required to enable their integration with multifunctional and multichannel electronic devices. In this work, a novel electrochemical gelation ("electrogelation") method is presented for rapidly patterning PEDOT:PSS hydrogels on any conductive template, including curved and 3D surfaces. High spatial resolution is achieved through use of a sacrificial metal layer to generate the hydrogel pattern, thereby enabling high-performance conducting hydrogels and aerogels with desirable material properties to be introduced into increasingly complex device architectures.

Injectable dynamic covalent hydrogels of boronic acid polymers cross-linked by bioactive plant-derived polyphenols.

We report here the development of hydrogels formed at physiological conditions using PEG (polyethylene glycol) based polymers modified with boronic acids (BAs) as backbones and the plant derived polyphenols ellagic acid (EA), epigallocatechin gallate (EGCG), tannic acid (TA), nordihydroguaiaretic acid (NDGA), rutin trihydrate (RT), rosmarinic acid (RA) and carminic acid (CA) as linkers. Rheological frequency sweep and single molecule force spectroscopy (SMFS) experiments show that hydrogels linked with EGCG and TA are mechanically stiff, arising from the dynamic covalent bond formed by the polyphenol linker and boronic acid functionalized polymer. Stability tests of the hydrogels in physiological conditions revealed that gels linked with EA, EGCG, and TA are stable. We furthermore showed that EA- and EGCG-linked hydrogels can be formed via in situ gelation in pH 7.4 buffer, and provide long-term steady state release of bioactive EA. In vitro experiments showed that EA-linked hydrogel significantly reduced the viability of CAL-27 human oral cancer cells via gradual release of EA.

[Cardioprotection of ramipril and BQ-123 against myocardial ischemia/reperfusion injury in vivo in rats].

AIM: To study the protective effects of ramipril in combination with BQ-123 on myocardial ischemia/reperfusion (I/R) injury in vivo in anesthetized rats. METHODS: Healthy male Wistar rats were divided into 5 groups randomly and subjected to 30 min of myocardial ischemia followed by 120 min reperfusion. Ramipril, BQ-123 and their combination were given to rats respectively. To observe the protection of their combination against myocardial I/R injury. HR, MAP and the change of ST-segment were observed. Ventricular arrthymias were monitored. The activity of creatine kinase (CK) and lactate dehydrogenase (LDH) in plasma, the infarct size and morphologic change were examined. RESULTS: Compared with I/R group, the elevation of ST-segment was decreased. Onsets of VPC and VT were delayed, durations of VPC and VT were shortened, especially their combination. Incidences of VPC, VT and VF were decreased. Activity of plasma CK and LDH was decreased, especially their combination. IS, IS/AAR and the morphology of myocardium were improved, especially their combination. CONCLUSION: Ramipril, BQ-123 and combined using these two agents protected myocardium from I/R injury in vivo. The protective effects on delaying onset of VA, shortening duration of VA, decreasing the activities of CK and LDH, decreasing infrarct size and improving morphology of myocardium were better than using ramipril and BQ-123 alone.