Solid composite electrolytes (SCEs) are regarded as an effective solution to ensure safety and enhance the energy density of lithium-based batteries. This work reports an ultrathin SCE membrane (∼ 15 μm) based on Li6.4La3Zr1.4Ta0.6O12/PVDF-HFP/LiTFSI/succinonitrile; it not only possesses good ionic conductivity (6.53 × 10–4 S cm–1 with a little amount of liquid electrolyte) at 30 °C and a satisfactory lithium ion transfer number (0.55 without electrolyte), but also exhibits excellent thermal and mechanical properties. A symmetric cell with SCE succinonitrile-10% (SN-10%) can be continuously cycled without short circuit at 0.2 mA cm–2 for about 340 h. Moreover, a high reversible discharge capacity of 150.2 mAh g–1 at 0.5 C was maintained by the cell (LiFePO4/SCE SN-10%/Li) after 269 cycles at room temperature. Notably, a capacity of about 100 mAh g–1 at 5 C was also obtained. This work might guide the improvement of future solid-state lithium/sodium metal batteries and lithium–sulfur batteries, even for wearable flexible batteries.

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Polyoxometalate (POM)-based metal–organic framework (MOF)-derived Co 3 O 4 /CoMoO 4 nanohybrids were successfully fabricated by a facile solvothermal method combined with a calcination process, in which a Co-based MOF, that is, ZIF-67 acts as a template while a Keggin-type POM (H 3 PMo 12 O 40 ) serves as a compositional modulator. The materials were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) mapping, and electrochemical measurements. When the Co 3 O 4 /CoMoO 4 nanohybrids were applied as anode materials for lithium-ion batteries (LIBs), they display large lithium storage capacity (around 900 mAh g –1 at 0.1 A g –1 ) and high cycling stability, and they can also exhibit good rate performances. This work might shed some light on the POM-based MOF host–guest synthesis strategy for the preparation of polymetallic oxides for enhanced electrochemical energy storage and further applications.

Anion-immobilized solid composite electrolytes (SCEs) are important to restrain the propagation of lithium dendrites for all solidstate lithium metal batteries (ASSLMBs). Herein, a novel SCEs based on metal-organic frameworks (MOFs, UiO-66-NH 2 ) and superacid ZrO 2 (S-ZrO 2 ) fillers are proposed, and the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), thermo-gravimetric analyzer (TGA) and some other electrochemical measurements. The -NH 2 groups of UiO-66-NH 2 combines with F atoms of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) chains by hydrogen bonds, leading to a high electrochemical stability window of 5 V. Owing to the incorporation of UiO-66-NH 2 and S-ZrO 2 in PVDF-HFP polymer, the open metal sites of MOFs and acid surfaces of S-ZrO 2 can immobilize anions by strong Lewis acid-base interaction, which enhances the effect of immobilization anions, achieving a high Li-ion transference number (t + ) of 0.72, and acquiring a high ionic conductivity of 1.05×10 -4 S•cm -1 at 60°C. The symmetrical Li/Li cells with the anion-immobilized SCEs may steadily operate for over 600 h at 0.05 mA•cm -2 without the shortcircuit occurring. Besides, the solid composite Li/LiFePO 4 (LFP) cell with the anion-immobilized SCEs shows a superior discharge specific capacity of 158 mAh•g -1 at 0.2 C. The results illustrate that the anion-immobilized SCEs are one of the most promising choices to optimize the performances of ASSLMBs.

All-solid-state Li-ion batteries (ASSLIBs) have been widely studied to achieve Li-ion batteries (LIBs) with high safety and energy density. Recent reviews and experimental papers have focused on methods that improve the ionic conductivity, stabilize the electrochemical performance, and enhance the electrolyte/electrode interfacial compatibility of several solid-state electrolytes (SSEs), including oxides, sulfides, composite and gel electrolytes, and so on. Garnet-structured Li 7 La 3 Zr 2 O 12 (LLZO) is highly regarded an SSE with excellent application potential. However, this type of electrolyte also possesses a number of disadvantages, such as low ionic conductivity, unstable cubic phase, and poor interfacial compatibility with anodes/cathodes. The benefits of LLZO have urged many researchers to explore effective solutions to overcome its inherent limitations. Herein, we review recent developments on garnet-structured LLZO and provide comprehensive insights to guide the development of garnet-structured LLZO-type electrolytes. We not only systematically and comprehensively discuss the preparation, element doping, structure, stability, and interfacial improvement of LLZOs but also provide future perspectives for these materials. This review expands the current understanding on advanced solid garnet electrolytes and provides meaningful guidance for the commercialization of ASSLIBs.