Highly Efficient Spatially-Temporally Synchronized Construction of Robust Li3 PO4 -rich Solid-Electrolyte Interphases in Aqueous Li-ion Batteries.

Solid electrolyte interphase (SEI) makes the electrochemical window of aqueous electrolytes beyond the thermodynamics limitation of water. However, achieving the energetic and robust SEI is more challenging in aqueous electrolytes because the low SEI formation efficiency (SFE) only contributed from anion-reduced products, and the low SEI formation quality (SFQ) negatively impacted by the hydrogen evolution, resulting in a high Li loss to compensate for SEI formation. Herein, we propose a highly efficient strategy to construct Spatially-Temporally Synchronized (STS) robust SEI by the involvement of synergistic chemical precipitation-electrochemical reduction. In this case, a robust Li3 PO4 -rich SEI enables intelligent inherent growth at the active site of the hydrogen by the chemical capture of the OH- stemmed from the HER to trigger the ionization balance of dihydrogen phosphate (H2 PO4 - ) shift to insoluble solid Li3 PO4 . It is worth highlighting that the Li3 PO4 formation does not extra-consume lithium derived from the cathode but makes good use of the product of HER (OH- ), prompting the SEI to achieve 100 % SFE and pushing the HER potential into -1.8 V vs. Ag/AgCl. This energetic and robust SEI offers a new way to achieve anion/concentration-independent interfacial chemistry for the aqueous batteries.

Lithium Salt Dissociation Promoted by 18-Crown-6 Ether Additive toward Dilute Electrolytes for High Performance Lithium Oxygen Batteries.

Lithium-oxygen batteries (LOBs) are well known for their high energy density. However, their reversibility and rate performance are challenged due to the sluggish oxygen reduction/evolution reactions (ORR/OER) kinetics, serious side reactions and uncontrollable Li dendrite growth. The electrolyte plays a key role in transport of Li+ and reactive oxygen species in LOBs. Here, we tailored a dilute electrolyte by screening suitable crown ether additives to promote lithium salt dissociation and Li+ solvation through electrostatic interaction. The electrolyte containing 100 mM 18-crown-6 ether (100-18C6) exhibits enhanced electrochemical stability and triggers a solution-mediated Li2 O2 growth pathway in LOBs, showing high discharge capacity of 10 828.8 mAh gcarbon -1 . Moreover, optimized electrode/electrolyte interfaces promote ORR/OER kinetics on cathode and achieve dendrite-free Li anode, which enhances the cycle life. This work casts new lights on the design of low-cost dilute electrolytes for high performance LOBs.

Electrolytes for Rechargeable Lithium-Air Batteries.

Lithium-air batteries are promising devices for electrochemical energy storage because of their ultrahigh energy density. However, it is still challenging to achieve practical Li-air batteries because of their severe capacity fading and poor rate capability. Electrolytes are the prime suspects for cell failure. In this Review, we focus on the opportunities and challenges of electrolytes for rechargeable Li-air batteries. A detailed summary of the reaction mechanisms, internal compositions, instability factors, selection criteria, and design ideas of the considered electrolytes is provided to obtain appropriate strategies to meet the battery requirements. In particular, ionic liquid (IL) electrolytes and solid-state electrolytes show exciting opportunities to control both the high energy density and safety.

An "Ether-In-Water" Electrolyte Boosts Stable Interfacial Chemistry for Aqueous Lithium-Ion Batteries.

Aqueous batteries are promising devices for electrochemical energy storage because of their high ionic conductivity, safety, low cost, and environmental friendliness. However, their voltage output and energy density are limited by the failure to form a solid-electrolyte interphase (SEI) that can expand the inherently narrow electrochemical window of water (1.23 V) imposed by hydrogen and oxygen evolution. Here, a novel (Li4 (TEGDME)(H2 O)7 ) is proposed as a solvation electrolyte with stable interfacial chemistry. By introducing tetraethylene glycol dimethyl ether (TEGDME) into a concentrated aqueous electrolyte, a new carbonaceous component for both cathode-electrolyte interface and SEI formation is generated. In situ characterizations and ab initio molecular dynamics (AIMD) calculations reveal a bilayer hybrid interface composed of inorganic LiF and organic carbonaceous species reduced from Li+ 2 (TFSI- ) and Li+ 4 (TEGDME). Consequently, the interfacial films kinetically broaden the electrochemical stability window to 4.2 V, thus realizing a 2.5 V LiMn2 O4 -Li4 Ti5 O12 full battery with an excellent energy density of 120 W h kg-1 for 500 cycles. The results provide an in-depth, mechanistic understanding of a potential design of more effective interphases for next-generation aqueous lithium-ion batteries.

Reducing the overpotential of an aprotic Li-O2 battery using a conductive graphene interlayer.

An aprotic Li-O2 battery incorporating a conductive graphene interlayer displays an ultralow overpotential of 0.67 V and a stable cyclability over 200 cycles at a high current density of 500 mA g-1. The improved performance of the battery is attributed to the role of the graphene interlayer in boosting the formation and decomposition of discharge products.