In Situ Polymerized 1,3-Dioxolane Electrolyte for Integrated Solid-State Lithium Batteries.

Solid-state lithium batteries are promising and safe energy storage devices for mobile electronics and electric vehicles. In this work, we report a facile in situ polymerization of 1,3-dioxolane electrolytes to fabricate integrated solid-state lithium batteries. The in situ polymerization and formation of solid-state dioxolane electrolytes on interconnected carbon nanotubes (CNTs) and active materials is the key to realizing a high-performance battery with excellent interfacial contact among CNTs, active materials and electrolytes. Therefore, the electrodes could be tightly integrated into batteries through the CNTs and electrolyte. Electrons/ions enable full access to active materials in the whole electrode. Electrodes with a low resistance of 4.5â€…Ω â–¡-1 and high lithium-ion diffusion efficiency of 2.5×10-11  cm2 s-1 can significantly improve the electrochemical kinetics. Subsequently, the batteries demonstrated high energy density, amazing charge/discharge rate and long cycle life.

Dual-Network Structured Hydrogel Electrolytes Engaged Solid-State Rechargeable Zn-Air/Iodide Hybrid Batteries.

As a key component of batteries, the electrolyte determines the ion transport and interface chemistry of the cathode and anode. In this work, we develop a dual-network structured hydrogel electrolyte composed of polyacrylamide (PAM), sodium alginate (SA) and potassium iodide (KI) for solid-state zinc-air/iodide hybrid batteries. The assembled hybrid battery shows excellent renewability and a long cycling life of 110 h with a high energy efficiency of 80 %. The ion-crosslinked dual-network structure endows the material with improved mechanical strength and increased ionic conductivity. More importantly, the introduction of iodine species not only offers more favorable cathodic kinetics of iodide/iodate redox than oxygen electrocatalysis but also regulates the solvation structure of zinc ions to ensure better interface stability. This work provides significant concepts for developing novel solid-state electrolytes to realize high-performance energy devices and technologies.

Metal-Organic Framework-Derived Carbon/Carbon Nanotubes Mediate Impedance Matching for Strong Microwave Absorption at Fairly Low Temperatures.

The use of magnetic particles and carbon materials, particularly those with compatible dielectric and magnetic loss, is crucial in managing microwave pollution. However, the mismatched impedance of currently available absorbers constrains their practical applications. Herein, we demonstrate the potential of a metal-organic framework (MOF)-derived composite whose impedance matching is optimized through spraying and immersion of MOF precursors in carbon nanotube socks followed by carbonization. The composite presents extremely strong microwave absorption with a reflection loss of -30 dB, a thin thickness of 1.5 mm, and a wide frequency bandwidth of 7.8 GHz. The excellent absorption can still be maintained even at a fairly low temperature of -40 °C. Such results are primarily attributed to the synergistic effect between the hierarchical architecture and multiple components that greatly optimizes the impedance matching. We believe that the composite is a promising microwave absorber that can help to solve the critical electromagnetic wave pollution.

A Dendrite-Free Lithium/Carbon Nanotube Hybrid for Lithium-Metal Batteries.

Lithium (Li) metal is promising in the next-generation energy storage systems. However, its practical application is still hindered by the poor cycling performance and serious safety issues for the consequence of dendritic Li. Herein, a dendrite-free Li/carbon nanotube (CNT) hybrid is proposed, which is fabricated by direct coating molten Li on CNTs, for Li-metal batteries. The favorable thermodynamic and kinetic conditions are the powerful force to drive the rapid lift upwards and infusion of molten Li into CNTs network, which is the key to form a uniform metallic layer in Li/CNTs hybrid. The obtained hybrid indicates super-stable functions even at an ultrahigh current density of 40 mA cm-2 for 2000 cycles with a stripping/plating capacity of 2 mAh cm-2 in symmetric cells. Subsequently, this hybrid also demonstrates a significantly decreased resistance, excellent cycling stability at high current density and flexibility in the full Li-S battery. This work provides valuable concepts in fabricating Li anodes toward Li-metal batteries and beyond for their high-level services.

Protecting Silicon Film Anodes in Lithium-Ion Batteries Using an Atomically Thin Graphene Drape.

Silicon (Si) shows promise as an anode material in lithium-ion batteries due to its very high specific capacity. However, Si is highly brittle, and in an effort to prevent Si from fracturing, the research community has migrated from the use of Si films to Si nanoparticle based electrodes. However, such a strategy significantly reduces volumetric energy density due to the porosity of Si nanoparticle electrodes. Here we show that contrary to conventional wisdom, Si films can be stabilized by two strategies: (a) anchoring the Si films to a carbon nanotube macrofilm (CNM) current collector and (b) draping the films with a graphene monolayer. After electrochemical cycling, the graphene-coated Si films on CNM resembled a tough mud-cracked surface in which the graphene capping layer suppresses delamination and stabilizes the solid electrolyte interface. The graphene-draped Si films on CNM exhibit long cycle life (>1000 charge/discharge steps) with an average specific capacity of ∼806 mAh g-1. The volumetric capacity averaged over 1000 cycles of charge/discharge is ∼2821 mAh cm-3, which is 2 to 5 times higher than what is reported in the literature for Si nanoparticle based electrodes. The graphene-draped Si anode could also be successfully cycled against commercial cathodes in a full-cell configuration.

A Foldable Lithium-Sulfur Battery.

The next generation of deformable and shape-conformable electronics devices will need to be powered by batteries that are not only flexible but also foldable. Here we report a foldable lithium-sulfur (Li-S) rechargeable battery, with the highest areal capacity (∼3 mAh cm(-2)) reported to date among all types of foldable energy-storage devices. The key to this result lies in the use of fully foldable and superelastic carbon nanotube current-collector films and impregnation of the active materials (S and Li) into the current-collectors in a checkerboard pattern, enabling the battery to be folded along two mutually orthogonal directions. The carbon nanotube films also serve as the sulfur entrapment layer in the Li-S battery. The foldable battery showed <12% loss in specific capacity over 100 continuous folding and unfolding cycles. Such shape-conformable Li-S batteries with significantly greater energy density than traditional lithium-ion batteries could power the flexible and foldable devices of the future including laptops, cell phones, tablet computers, surgical tools, and implantable biomedical devices.