Phase regulation enabling dense polymer-based composite electrolytes for solid-state lithium metal batteries.

Solid polymer electrolytes with large-scale processability and interfacial compatibility are promising candidates for solid-state lithium metal batteries. Among various systems, poly(vinylidene fluoride)-based polymer electrolytes with residual solvent are appealing for room-temperature battery operations. However, their porous structure and limited ionic conductivity hinder practical application. Herein, we propose a phase regulation strategy to disrupt the symmetry of poly(vinylidene fluoride) chains and obtain the dense composite electrolyte through the incorporation of MoSe2 sheets. The electrolyte with high dielectric constant can optimize the solvation structures to achieve high ionic conductivity and low activation energy. The in-situ reactions between MoSe2 and Li metal generate Li2Se fast conductor in solid electrolyte interphase, which improves the Coulombic efficiency and interfacial kinetics. The solid-state Li||Li cells achieve robust cycling at 1 mA cm-2, and the Li||LiNi0.8Co0.1Mn0.1O2 full cells show practical performance at high rate (3C), high loading (2.6 mAh cm-2) and in pouch cell.

Specific Adsorption-Oxidation Strategy in Cathode Inner Helmholtz Plane Enabling 4.6 V Practical Lithium-Ion Full Cells.

Increasing the cutoff voltage effectively maximizes the available capacity of the state-of-art layered-oxide cathodes (LiTMO2). However, the spontaneous dehydrogenation-oxidation of carbonates in the cathode inner Helmholtz plane (C-IHP) under high voltage/temperature leads to side effects, including weak cathode electrolyte interphase (CEI) and cathode structural collapse. Here, we report a specific adsorption-oxidation (Ad-O) mechanism that dominates the later CEI formation through molecular regulation in C-IHP. The two tailored additives with specific electron-rich groups will enter the C-IHP and mask the active sites of cathodes, thereby reducing the weak CEI generation from conventional carbonates. As-formed hierarchical CEI with inner LiF and outer B-F/-CN rich organic structure will further protect the aggressive cathode from harmful electrolyte corrosion under harsh conditions of high voltages (4.6 V) and elevated temperatures (60 °C). This synergistic strategy guided by the specific Ad-O mechanism enables 3.5 Ah LiNi0.8Co0.1Mn0.1O2/Graphite pouch cells, which remarkably achieve 270 Wh/kg with 450 cycles.

Electrocrystallization Regulation Enabled Stacked Hexagonal Platelet Growth toward Highly Reversible Zinc Anodes.

Realizing durative flattened and dendrite-free zinc (Zn) metal configuration is the key to resolving premature battery failure caused by the internal short circuit, which is highly determined by the crystal growth in the electrocrystallization process. Herein, we report that regulating the molecular structure of the inner Helmholtz plane (HIP) can effectively convert the deposition into activation control by weakening the solvated ion adsorption at the interface. The moderated electrochemical reaction kinetics lower than the adatom self-diffusion rate steers conformal stratiform Zn growth and dominant Zn (0001) texture, achieving crystallographic optimization. Through in situ mediation of electrolyte engineering, orientational plating and stripping behaviors at edge-sites and tailored solvation structure immensely improve the utilization efficiency and total charge passed of Zn metal, even under extreme conditions, including high areal capacity (3 mAh cm-2 ) and wide temperature range (-40-60 °C).

Outside-In Nanostructure Fabricated on LiCoO2 Surface for High-Voltage Lithium-Ion Batteries.

The energy density of batteries with lithium cobalt oxide (LCO) can be maximized by increasing the cut-off voltage to approach the theoretical capacity limit. However, it is not realized in the practical applications due to the restricted cycle life caused by vulnerable cathode surface in deep delithiation state, where severe side reactions, oxygen/cobalt loss and structure degradation often happen. Here, an outside-in oriented nanostructure on LiCoO2 crystals is fabricated. The outer electrochemically stable LiF and Li2 CoTi3 O8 particles perform as physical barrier to prevent damage of both cathodes and electrolytes, while the inner F doping promote Li ions diffusivity and stabilize the lattice oxygen. With the spinel-like transition layer between them, a solid and complete lithium-ion transport channel generation along the lithium concentration gradient. Under the protection from this structure, the LiCoO2 withstand the high voltage of 4.6 V and the LCO/graphite pouch full cell with high loading density exhibits 81.52% energy density retention after 135 cycles at 4.5 V.

Advanced liquid electrolytes enable practical applications of high-voltage lithium-metal full batteries.

High-voltage lithium metal batteries (HVLMBs) have received widespread attention as next generation high-energy-density batteries to meet the urgent demands of modern life. However, the unstable interphase between electrolytes and highly reactive electrodes is still an important threshold for practical applications. In this feature article, we review the formation mechanism of the electrode-electrolyte interphase in terms of cathodes and the Li metal anode, respectively, and summarize the surface modification methods to stabilize the interphase of HVLMBs. Electrolyte regulation strategies especially those using electrolyte additives are introduced, and the relationship between liquid electrolyte formulation, interphase engineering and the electrochemical performance of HVLMBs is analyzed. Finally, an industry-level evaluation is carried out and the remaining challenges are discussed for advanced electrolytes to guarantee the practical applications and commercialization of HVLMBs.

Tuning the Interfacial Electronic Conductivity by Artificial Electron Tunneling Barriers for Practical Lithium Metal Batteries.

The native solid electrolyte interphase (SEI) in lithium metal batteries (LMBs) cannot effectively protect Li metal due to its poor ability to suppress electron tunneling, which may account for the increase of the SEI and even dead Li. It is desirable to introduce artificial electron tunneling barriers (AETBs) with ultrahigh insulativity and chemical stability to maintain a sufficiently low electronic conductivity of the SEI. Herein, a nanodiamond particle (ND)-embedded SEI is constructed by a self-transfer process. The ND serving as the AETB reduces the risk of electron penetration through the SEI, readjusts the electric field at the interface, and eliminates the tip effect. As a result, a dendrite-free morphology and dense massive microstructure of Li deposition are realized even with high areal capacity. Notably, full cells using ultrathin Li anodes (45 µm) and LiNi0.8Co0.1Mn0.1O2 cathodes (4.3 mA h cm-2) can cycle stably over 110 cycles, demonstrating that the AETB-embedded SEI significantly alleviates the anode pulverization and safety concerns in practical LMBs.

A general catalyst for Suzuki-Miyaura and Sonogashira reactions of aryl and heteroaryl chlorides in water.

We report the synthesis of 2-(3-sulfonatomesityl)-5-sulfonatoindenyl)dicyclohexylphosphine hydrate sodium salt and its use in palladium-catalyzed Suzuki-Miyaura and Sonogashira coupling reactions in water (and biphasic water-organic solvent mixtures) to prepare a variety of functionalized biaryls and aryl alkynes in excellent yield.

A highly active catalytic system for Suzuki-Miyaura cross-coupling reactions of aryl and heteroaryl chlorides in water.

An easily available Pd(OAc)(2)/(2-mesitylindenyl)dicyclohexylphosphine/Me(octyl)(3)N(+)Cl(-)/K(3)PO(4)·3H(2)O catalytic system was developed and it shows high catalytic activity in the Suzuki-Miyaura cross-coupling reaction of a diverse array of aryl and heteroaryl chlorides in water. Notably, this catalytic system also works with ultra-low loading of the catalyst with high turnover numbers.

Phenyl substituted indenylphosphine ruthenium complexes as catalysts for dehydrogenation of alcohols.

Thermal treatment of (1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (1) and (3-mesityl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (3) with tBuONa followed by [(η(6)-cymene)RuCl(2))](2) in methanol gave the adduct {(η(6)-cymene)RuCl(2)[(1H-inden-3-yl)PCy(2)]} (6) and {(η(6)-cymene)RuCl(2)[(3-mesityl-1H-inden-3-yl)PCy(2)]} (7), respectively. Thermal treatment of (2-phenyl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (4) with tBuONa followed by [(η(6)-cymene)RuCl(2))](2) or RuCl(3)·3H(2)O in methanol gave {Ru[κ(P):(η(6)-2-phenyl-1H-inden-3-yl)PCy(2)]Cl(2)} (8). Whereas (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (5) reacted with [(η(6)-cymene)RuCl(2))](2) (in toluene) or RuCl(3)·3H(2)O (in ethanol) to afford {Ru[κ(P):(η(6)-2-mesityl-1H-inden-3-yl)PCy(2)]Cl(2)} (9). The molecular structures of complexes 6, 8 and 9 have been determined by single-crystal X-ray diffraction analysis. In addition, complexes 8 and 9 have been found to catalyze the acceptorless dehydrogenation of alcohols in toluene. 9 displayed high activity and different substrates, including cyclic and linear alcohols, were efficiently oxidized to ketones by using 2.0 mol% of catalyst.