A brightener-inspired polymer interphase enables highly reversible aqueous Zn anodes via suppressing side-reactions and manipulating the nucleation process.

The surface chemistry of solid electrolyte interphase is one of the critical factors that govern the cycling life of rechargeable batteries. However, this chemistry is less explored for zinc anodes, owing to their relatively high redox potential and limited choices in electrolyte. Here, we report the observation of a zinc fluoride-rich organic/inorganic hybrid solid electrolyte interphase on zinc anode, based on an acetamide-Zn(TFSI)2 eutectic electrolyte. A combination of experimental and modeling investigations reveals that the presence of anion-complexing zinc species with markedly lowered decomposition energies contributes to the in situ formation of an interphase. The as-protected anode enables reversible (~100% Coulombic efficiency) and dendrite-free zinc plating/stripping even at high areal capacities (>2.5 mAh cm‒2), endowed by the fast ion migration coupled with high mechanical strength of the protective interphase. With this interphasial design the assembled zinc batteries exhibit excellent cycling stability with negligible capacity loss at both low and high rates.

In-situ constructing multifunctional solid electrolyte interphase (SEI) for Zn anode is promising to address the dendrite growth and side reactions (corrosion and hydrogen evolution) in aqueous Zn-ion batteries. However, there...

Low ionic conductivity at room temperature and limited electrochemical window of poly(ethylene oxide) (PEO) are the bottlenecks restricting its further application in high‐energy density lithium metal battery. Herein, a differentiated salt designed multilayered PEO‐based solid polymer electrolyte (DSM‐SPE) is exploited to achieve excellent electrochemical performance toward both the high‐voltage LiCoO2 cathode and the lithium metal anode. The LiCoO2/Li metal battery with DSM‐SPE displays a capacity retention of 83.3% after 100 cycles at 60 °C with challenging voltage range of 2.5 to 4.3 V, which is the best cycling performance for high‐voltage (≥4.3 V) LiCoO2/Li metal battery with PEO‐based electrolytes up to now. Moreover, the Li/Li symmetrical cells present stable and low polarization plating/stripping behavior (less than 80 mV over 600 h) at current density of 0.25 mA cm−2 (0.25 mAh cm−2). Even under a high‐area capacity of 2 mAh cm−2, the profiles still maintain stable. The pouch cell with DSM‐SPE exhibits no volume expansion, voltage decline, ignition or explosion after being impaled and cut at a fully charged state, proving the excellent safety characteristic of the DSM‐SPE‐based lithium metal battery.

Nonflammable functional electrolytes with remarkably interfacial compatibility toward both lithium anodes and high-voltage cathodes are considered as the ultimate pursuit for rechargeable lithium metal battery. For this target, we report a dual-anion deep eutectic solution (D-DES) based on elaborately selected combination of nitrile and functional lithium salts. The interactions of succinonitrile with cation/anion are highlighted by in situ/ex situ measurements, which endow D-DES with excellent ionic conductivity and significantly enhanced interface stability. By using this D-DES, constant Li|Li cycling over 1 year (>10,000 h) under a Li capacity of 5 mA h cm–2 can be achieved. The capacity retention is still over 70% with a high charging voltage of 4.7 V for 500 cycles in LiCoO2|Li battery. Pouch cells with high areal capacity close to practical application also deliver superior safe performance. This study paves a new pathway for designing high-safety electrolyte and boosts the practical application of high-voltage lithium metal battery.

The inhomogeneous deposition/dissolution of Li metal and an unstable SEI layer are still tough issues for lithium metal batteries, causing severe safety problems and low Coulombic efficiency. In this paper, we design an artificial SEI layer based on in situ polymerization of ethyl α-cyano­acrylate precursor with LiNO3 additive. The CN– and NO3 – groups can react with lithium metal during cycling to form a nitrogenous interface inorganic layer, facilitating ions conduction and blocking further undesirable interface reaction. The poly­(ethyl α-cyano­acrylate) with excellent mechanical property presents as the dominate organic species in the artificial SEI layer to offer a uniform and firm protective outer layer. A lithium metal battery with this artificial SEI film exhibits a capacity retention of 93% even after 500 cycles at a rate of 2C. A smooth surface morphology of the lithium metal anode is obtained without any cracks and dendrites.

Layered ternary oxide cathode materials LiNi x Mn y Co1–x–y O2 (NMC) and LiNi x Co y Al1–x–y O2 (NCA) (referred to as ternary cathode materials, TCMs) with large reversible capacity, high operating voltage as well as low cost are considered as the most potential candidate materials for high energy density lithium ion batteries (LIBs) used in hybrid electric vehicles and electric vehicles (EVs). However, next-generation long-range EVs require an energy density of 800 W h kg–1 at the cathode level, which cannot be obtained using the commercially available TCMs. Developing high-voltage TCMs is a promising solution to enhance energy density of LIBs. Nonetheless, the capacity decay, poor long-term cycle life and microcrack at high operating voltage have limited their practical applications. In this paper, the development of the high-voltage TCMs is reviewed from degradation mechanism, cathode electrode modification, electrolyte design, solid state electrolytes and so on. The critical factors, recent progress and perspectives that improve the performance of TCMs with high-voltage operation are reviewed, which could provide important information and precautions to the practical use of these cathode materials under high operating voltage.

In situ polymerization system can provide a compact and compatible interface with minimum polymer electrolyte, which is imperative to address the bottleneck of notorious solid−solid interface issues for high-energy-density solid-state batteries. However, the existing in situ formed solid-state electrolyte still faces many problems, such as low polymerization conversion and inferior high-voltage stability, prohibiting its applications in practical high-voltage lithium-metal batteries. Herein, we present a deep eutectic solvent (DES)-based in situ polymerized solid electrolyte, which is facile and well matched with the commercially available lithium-ion battery technology. The DES precursor is made from a molten mixture of solid powders, containing a synthesized monomer named (2-(((2-oxo-1,3-dioxolan-4-yl) methoxy) carbonylamino))-ethyl methacrylate (CUMA), a succinonitrile (SN) plastic crystal, and two kinds of lithium salts. After in situ ploymerization triggered by free radical, the liquid again turns into a solid composite electrolyte (PDES-CPE) with a superior polymerization conversion of 99.8%. It delivers a promising lithium-ion conductivity (1.07 × 10 −3 S/cm with a high lithium-ion transference number of 0.62 at 30 °C) and prominent high-voltage stability (100 cycles with 82.4% capacity retention coupled with 4.6 V LiCoO 2 cathode). Through in situ Fourier transform infrared (FTIR) spectroscopy, we reveal a robust interface chemistry with thermodynamically improved high-voltage stability (compared to polyether-based electrolyte). This as-presented strategy makes a big leap to address the interface issues and boost the development of high-energy-density solid-state lithium-metal batteries.