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The application of flexible, robust, and low-cost solid polymer electrolytes in next-generation all-solid-state lithium metal batteries has been hindered by the low room-temperature ionic conductivity of these electrolytes and the small critical current density of the batteries. Both issues stem from the low mobility of Li+ ions in the polymer and the fast lithium dendrite growth at the Li metal/electrolyte interface. Herein, Mg(ClO4)2 is demonstrated to be an effective additive in the poly(ethylene oxide) (PEO)-based composite electrolyte to regulate Li+ ion transport and manipulate the Li metal/electrolyte interfacial performance. By combining experimental and computational studies, we show that Mg2+ ions are immobile in a PEO host due to coordination with ether oxygen and anions of lithium salts, which enhances the mobility of Li+ ions; more importantly, an in-situ formed Li+-conducting Li2MgCl4/LiF interfacial layer homogenizes the Li+ flux during plating and increases the critical current density up to a record 2 mA cm-2. Each of these factors contributes to the assembly of competitive all-solid-state Li/Li, LiFePO4/Li, and LiNi0.8Mn0.1Co0.1O2/Li cells, demonstrating the importance of surface chemistry and interfacial engineering in the design of all-solid-state Li metal batteries for high-current-density applications.

The unclear Li+ local environment and Li+ conduction mechanism in solid polymer electrolytes, especially in a ceramic/polymer composite electrolyte, hinder the design and development of a new composite electrolyte. Moreover, both the low room-temperature Li+ conductivity and large interfacial resistance with a metallic lithium anode of a polymer membrane limit its application below a relatively high temperature. Here we have identified the Li+ distribution and Li+ transport mechanism in a composite polymer electrolyte by investigating a new solid poly(ethylene oxide) (PEO)-based NASICON-LiZr2(PO4)3 composite with 7Li relaxation time and 6Li → 7Li trace-exchange NMR measurements. The Li+ population of the two local environments in the composite electrolytes depends on the Li-salt concentration and the amount of ceramic filler. A composite electrolyte with a [EO]/[Li+] ratio n = 10 and 25 wt % LZP filler has a high Li+ conductivity of 1.2 × 10-4 S cm-1 at 30 °C and a low activation energy owing to the additional Li+ in the mobile A2 environment. Moreover, an in situ formed solid electrolyte interphase layer from the reaction between LiZr2(PO4)3 and a metallic lithium anode stabilized the Li/composite-electrolyte interface and reduced the interfacial resistance, which provided a symmetric Li/Li cell and all-solid-state Li/LiFePO4 and Li/LiNi0.8Co0.1Mn0.1O2 cells a good cycling performance at 40 °C.

The application of solid-state batteries (SSBs) is challenged by the inherently poor interfacial contact between the solid-state electrolyte (SSE) and the electrodes, typically a metallic lithium anode. Building artificial intermediate nanofilms is effective in tackling this roadblock, but their implementation largely relies on vapor-based techniques such as atomic layer deposition, which are expensive, energy-intensive, and time-consuming due to the monolayer deposited per cycle. Herein, an easy and low-cost wet-chemistry fabrication process is used to engineer the anode/solid electrolyte interface in SSBs with nanoscale precision. This coordination-assisted deposition is initiated with polyacrylate acid as a functional polymer to control the surface reaction, which modulates the distribution and decomposition of metal precursors to reliably form a uniform crack-free and flexible nanofilm of a large variety of metal oxides. For demonstration, artificial Al

The unclear Li

A selective CO evolution from photoreduction of CO2 in water was achieved on a noble-metal-free, carbide-based composite catalyst, as demonstrated by a CO selectivity of 98.3% among all carbon-containing products and a CO evolution rate of 29.2 μmol h–1, showing superiority to noble-metal-based catalyst. A rapid separation of the photogenerated electron–hole pairs and improved CO2 adsorption on the surface of the carbide component are responsible for the excellent performance of the catalyst. The high CO selectivity is accompanied by a predominant H2 evolution, which is believed to provide a proton-deficient environment around the catalyst to favor the formation of hydrogen-deficient carbon products. The present work provides general insights into the design of a catalyst with a high product selectivity and also the carbon evolution chemistry during a photocatalytic reaction.

Potassium has as rich an abundance as sodium in the earth, but the development of a K-ion battery is lagging behind because of the higher mass and larger ionic size of K+ than that of Li+ and Na+, which makes it difficult to identify a high-voltage and high-capacity intercalation cathode host. Here we propose a cyanoperovskite KxMnFe(CN)6 (0 ≤ x ≤ 2) as a potassium cathode: high-spin MnIII/MnII and low-spin FeIII/FeII couples have similar energies and exhibit two close plateaus centered at 3.6 V; two active K+ per formula unit enable a theoretical specific capacity of 156 mAh g–1; Mn and Fe are the two most-desired transition metals for electrodes because they are cheap and environmental friendly. As a powder prepared by an inexpensive precipitation method, the cathode delivers a specific capacity of 142 mAh g–1. The observed voltage, capacity, and its low cost make it competitive in large-scale electricity storage applications.

A selective CO evolution from photoreduction of CO

Garnet-structured Li7La3Zr2O12 is a promising solid Li-ion electrolyte for all-solid-state Li-metal batteries and Li-redox-flow batteries owing to its high Li-ion conductivity at room temperature and good electrochemical stability with Li metal. However, there are still three major challenges unsolved: (1) the controversial electrochemical window of garnet, (2) the impractically large resistance at a garnet/electrode interface and the fast lithium-dendrite growth along the grain boundaries of the garnet pellet, and (3) the fast degradation during storage. We have found that these challenges are closely related to a thick Li2CO3 layer and the Li–Al–O glass phase on the surface of garnet materials. Here we introduce a simple method to remove Li2CO3 and the protons in the garnet framework by reacting garnet with carbon at 700 °C; moreover, the amount of the Li–Al–O glass phase with a low Li-ion conductivity in the grain boundary on the garnet surface was also reduced. The surface of the carbon-treated garnet...

Indium-oxide (In

A cross-linked polymer containing pendant molecules attached to the polymer framework is shown to form flexible and low-cost membranes, to be a solid Li(+) electrolyte up to 270 °C, much higher than those based on poly(ethylene oxide), to be wetted by a metallic lithium anode, and to be not decomposed by the metallic anode if the anions of the salt are blocked by a ceramic electrolyte in a polymer/ceramic membrane/polymer sandwich electrolyte (PCPSE). In this sandwich architecture, the double-layer electric field at the Li/polymer interface is reduced due to the blocked salt anion transfer. The polymer layer adheres/wets the lithium metal surface and makes the Li-ion flux at the interface more homogeneous. This structure integrates the advantages of the ceramic and polymer. With the PCPSE, all-solid-state Li/LiFePO4 cells showed a notably high Coulombic efficiency of 99.8-100% over 640 cycles.