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Garnet‐based solid‐state Li‐metal batteries (GSSBs) have the merits of high energy density and high safety. However, the realization of a stable and well‐matched Li|garnet interface for GSSBs remains challenging due to electron leakage and lithiophobic Li2CO3 impurity. To address these issues, herein, new surface chemistry is reported that converts the undesired Li2CO3 contaminant into an ultra‐thin lithium polyphosphate (Li‐PPA) layer through anhydrous polyphosphoric acid ‐induced in situ substitution reaction without damaging the water‐sensitive garnet electrolyte. In particular, the Li‐PPA interlayer not only facilitates the homogenous spreading of molten Li but also creates a robust electron‐blocking shield to suppress Li dendrite formation. As a result, the assembled Li symmetric cell exhibits a low interfacial impedance (4 Ω cm2) and high critical current density (1.8 mA cm−2) at 25 °C, which enables the cell to continuously cycle over 2500 h at 0.2 mA cm−2. Furthermore, the GSSBs paired with LiFePO4 deliver a high capacity of 149.3 mAh g−1 at 1 C and maintain 92.3% of the initial capacity after 500 cycles and can be used for solar energy storage, suggesting the feasibility of this interfacial engineering strategy for GSSBs. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes (GPEs) are intrinsically advantageous over rigid inorganic ones due to their easy processability and scalability. However, in terms of poor mechanical strength, GPEs can hardly satisfy the requirement of practical Li metal batteries. Herein, a novel one‐dimensional Cu‐metal–organic framework (MOF)‐filler‐reinforced GPE with the merits of high mechanical strength and high ionic conductivity is developed. When such GPE is used in Li symmetrical cells, small and stable Li‐plating/stripping overpotentials (~50 mV) can be maintained over 350 h at.3 mA/cm2. Benefitting from the above MOF‐filler‐reinforced GPE, a full cell with the Li metal anode and LiFePO4 cathode presents a stable cycling performance with a low capacity decay rate of.004% per cycle over 800 cycles at 1 C. [ABSTRACT FROM AUTHOR]

The self‐catalyzed growth of nanostructures on material surfaces is one of the most time‐ and cost‐effective ways to design multifunctional catalysts for a wide range of applications. Herein, the use of this technique to develop a multicomponent composite catalyst with CoSx core encapsulated in an ultrathin porous carbon shell entangled with Co, N‐codoped carbon nanotubes is reported. The as‐prepared catalyst has a superior catalytic activity for oxygen evolution and oxygen reduction reactions, an ultralow potential gap of 0.74 V, and outstanding durability, surpassing most previous reports. Such superiority is ascribed, in part, to the unique 3D electrode architecture of the composite, which is favorable for transporting oxygen species and electrons and creates a synergy between the components with different functionalities. Moreover, the flexible solid Zn–air battery assembled with such an air electrode shows a steady discharge voltage plateau of 1.25 V and a round‐trip efficiency of 70% at 1 mA cm−2. This work presents a simple strategy to design highly efficient bifunctional oxygen electrocatalysts and may pave the way for the practical application of these materials in many energy conversion/storage devices. [ABSTRACT FROM AUTHOR]

Abstract Poor electrical conductivity of sulfur, sluggish redox kinetics, dissolution of intermediate polysulfides, and expansion in volume upon cycling are the main drawbacks that hamper the practical application of Li-S batteries. By taking advantages of the high conductivity and favorable catalytic activity of RuO 2 , we design a 3D carbon nanotube film with embedded RuO 2 nanoparticles as a freestanding type of chemisorptive and catalyst-like cathode for Li-S batteries, which can be facilely prepared by a surfactant-assisted vacuum infiltration method. Both experimental and theoretical results reveal the excellent capability of RuO 2 for anchoring polysulfides and accelerating the kinetics of polysulfides catalytic redox reactions. Besides, the 3D freestanding cathode is beneficial to overcoming pulverization during volume changes, especially for long-term cycling. At a high areal sulfur loading of 2 mg cm−2, favorable initial capacities of 750 and 1060 mA h g−1 respectively at 2 and 0.5 C are achieved. More attractively, the capacity after 1000 cycles maintains 405 mA h g−1 at 0.5 C with a loss in capacity of only 0.06% per cycle. Additionally, such freestanding cathode allows the batteries to be tested under various bending stages, hence encouraging more research works on fabrication of other 3D nanostructure families as high-performance cathodes for Li-S batteries. Graphical abstract A 3D free-standing catalyst-like cathode is designed and prepared for Li-S battery through a surfactant-assisted infiltration approach. Favorable high-rate performances and stabilities are delivered for Li-S battery with the as-prepared cathode due to the excellent chemisorption, high conductivity and for various redox reactions of RuO 2. The 3D free-standing catalyst-like cathode provides an inspirational model for promising flexible energy storage devices. Image 1 Highlights • A free-standing porous RuO 2 -embedded 3D CNT film is fabricated. • The freestanding film can overcome the pulverization of sulfur cathode. • Conductive RuO 2 shows favorable catalytic activity for polysulfides. • The cross-linked CNT enables the electron transport in whole cathode. • The Li-S battery with the freestanding cathode operates over 1000 cycles. [ABSTRACT FROM AUTHOR]

Considering significant safety advantages, all solid-state LIBs have attracted considerable attentions as alternative power sources for electric vehicles where safety is a big concern, while the development of solid electrolyte membrane with high lithium-ion conductivity, negligible electron conductivity and high stability is the key challenge. Here, Sr and Sb co-doping strategy was applied to further improve the sintering capability and conductivity properties of Li 7 La 3 Zr 2 O 12 garnet-type electrolytes. Specifically, Li 6.6+x La 3-x Sr x Zr 1.6 Sb 0.4 O 12 (x = 0–0.2) oxides were designed and the physical and electrochemical performance of the various materials were comparatively studied. The results of X-ray diffraction and Raman spectra revealed Li 6.6+x La 3-x Sr x Zr 1.6 Sb 0.4 O 12 (x = 0–0.2) prepared by conventional solid-state reaction was in cubic structure. The introduction of a small amount of Sr into the La sites is beneficial for membrane densification and lithium-ion mobility, turning out high density of 95.1% and ionic conductivity of 8.83 × 10−4 S cm−1 at room temperature. The EIS showed the doping of Sr in La sites resulted in improved conductivity at both grain boundary and the oxide bulk. The batteries consisting of lithium film anode, Li 6.66 La 2.94 Sr 0.06 Zr 1.6 Sb 0.4 O 12 solid electrolyte membrane and LiFePO 4 cathode reached the first discharge capacity of 157 mAh g−1 at 0.1 C between 4.2 and 2.0 V (vs. L/Li+) with capacity retention of 93% after 100 cycles at ambient temperature. These results displayed that the Sr, Sb co-doped LLZO electrolytes are alternative for all solid-state Li-ion batteries. Image 1 • A Sr, Sb co-doping strategy was used to design Li 7 La 3 Zr 2 O 12 electrolyte membrane. • A new garnet-type Li 6.66 La 2.94 Sr 0.06 Zr 1.6 Sb 0.4 O 12 (LLSZSO) membrane was developed. • The LLSZSO shows high ionic conductivity of 8.83 × 10−4 S cm−1 at room temperature. • The capacity of LLSZSO is 146 mAh g−1 with retention rate of 93% after 100 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Contact issue of the anode-electrolyte interface was tackled by a Li-Mo composite. • Lower cohesive energy and higher binding energy are beneficial to better contact. • Symmetric cell shows a high critical current density and a stable 1200-h cycling. • A full cell with a LiFePO 4 cathode presented stable performance for 200 cycles. • The work provides a facile and feasible way to overcome interface problems. Interface issues are the biggest challenges that hindering the commercialization of solid-state lithium metal batteries (SSLMBs). Here, we propose a novel strategy targeting for effectively resolving the tedious lithium-garnet solid electrolyte interface problem from the lithium side. We intentionally introduce α-MoO 3 nanobelts into the molten metallic lithium, forming a Li-Mo composite. Compared to molten lithium, the composite improves wettability on the garnet electrolyte. As revealed by density functional theory calculations, such improvement could be ascribed to the reduced cohesive energy and the improved interface binding energy to the LLZTO. Intimate surface contact can be easily achieved without complicated surface treatment, which not only significantly reduces the interface resistance to ~ 1 Ω cm2, but could also effectively inhibits the generation of lithium dendrites. These features ensure a significant critical current density of 1700 µA cm−2 and a stable electrochemical Li plating/stripping process for more than 1200 h. A full cell with the Li-Mo composite anode and LiFePO 4 cathode also presents a fairly stable cycling performance at room temperature. Different from most previous strategies that try to tackle the interface issues from the electrolyte side, our research results suggest that designing lithium composite anodes with low cohesive energy and high interface binding energy to the solid electrolyte is an attractive and feasible solution to overcome interface problems. [ABSTRACT FROM AUTHOR]