The high‐polarity β‐phase poly(vinylidene difluoride) (β‐PVDF), which has all trans conformation with F and H atoms located on the opposite sides of the polymer backbone, is demonstrated to be a ...promising artificial solid‐electrolyte interphase coating on both Cu and Li metal anodes for dendrite‐free Li deposition/stripping and enhanced cycling performance. A thin (≈4 µm) β‐PVDF coating on Cu enables uniform Li deposition/stripping at high current densities up to 5 mA cm−2, Li‐plating capacity loadings of up to 4 mAh cm−2, and excellent cycling stability over hundreds of cycles under practical conditions (1 mA cm−2 with 2 mAh cm−2). Full cells containing an LiFePO4 cathode and an anode of either β‐PVDF coated Cu or Li also exhibit excellent cycling stability. The profound effects of the high‐polarity PVDF coating on dendrite suppression are attributed to the electronegative F‐rich interface that favors layer‐by‐layer Li deposition. This study offers a new strategy for the development of dendrite‐free metal anode technology.
Li metal anodes with a thin β‐phase poly(vinylidene difluoride) coating demonstrate dendrite‐free Li deposition and enhanced cycling performance at practical current densities and capacity loadings. The high chemical polarity of the polymer with its preferentially sided F alignment provides a new strategy for optimizing the interfacial interactions that favor layer‐by‐layer Li deposition.
A mechanically robust and ion‐conductive polymeric coating containing two polymers, polyethylene glycol tert‐octylphenyl ether and poly(allyl amine), with four tailored functional groups is developed ...for graphite and graphite–Si composite anodes. The coating, acting as an artificial solid electrolyte interphase, leads to remarkable enhancement in capacity reversibility and cycling stability, as well as a high‐rate performance of the studied anodes.
A homogeneous Nb‐doped rutile TiO2 mesocrystal material was synthesized successfully through a facile hydrothermal route. The incorporation of Nb5+ not only promotes the crystallization of the ...building subunits of the rutile TiO2 mesocrystal, but also improves the electrochemical performance at higher current rates. A capacity of 96.3 mAh g−1 at a current density as high as 40 C and an excellent long‐term cycling stability with a capacity loss of approximately 0.006 % per cycle at 5 C could be achieved when an appropriate amount of Nb5+ was doped into rutile TiO2 mesocrystal. The reasons for the improvement of rate capability may be attributed to the enhancement of electronic conductivity, Li‐ion diffusion kinetics, and the surface storage property for the Nb‐doped rutile TiO2 mesocrystal.
(Meso)crystal clear: Nb‐doped rutile TiO2 mesocrystal was synthesized successfully through a facile hydrothermal route for the first time and exhibited an improved electrochemical performance at higher current rates, which might be attributed to the enhancement of electronic conductivity, Li‐ion diffusion kinetics, and surface storage ability.
Hierarchical TiO2-x imbedded with graphene quantum dots was synthesized through a facile synthetic route and investigated as an anode material for lithium-ion batteries. It delivers a high specific ...capacity and excellent rate capability (160.1 mA h g-1 at 10 C after 500 cycles).
Nanoporous anatase TiO2 mesocrystals with tunable architectures and crystalline phases were successfully fabricated in the presence of the butyl oleate and oleylamine. Especially, the introduced ...surfactants served as a carbon source, bring a uniform carbon layer (about 2–8 nm) for heightening the electronic conductivity. The carbon coated TiO2 mesocrystals assembled from crystalline tiny subunits have more space sites for sodium-ion storage. When the material was applied as an electrode material in rechargeable sodium-ion batteries, it exhibited a superior capacity of about 90 mA h g−1 at 20 C (1 C = 168 mA g−1) and a highly reversible capacity for 5000 cycles, which is the longest cycle life reported for sodium storage in TiO2 electrodes.
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•A new strategy was proposed for preparing carbon coated TiO2 mesocrystals.•Anatase TiO2 mesocrystals with tunable architectures were successfully formed.•A highly reversible capacity up to 5000 cycles was achieved.
In the present work, TiO 2 -B nanowires have been successfully synthesized for the first time based on a topological conversion process by using titanate as a precursor and exhibited a length of ...several hundred nanometers and a width of approximately 10 nm. This resulted in excellent electron/ion transport properties and reaction kinetics in lithium intercalation. Consequently, as an anode material for lithium-ion batteries, TiO 2 -B nanowires exhibited an extraordinary rate performance and outstanding long-term cycling stability with a capacity of 192.4 mA h g −1 after 3600 cycles at a rate as high as 10C.
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•Preparation of silicon-graphite composites via fluidized bed for lithium-ion anodes.•High capacity silicon-on-graphite composites with ≈600mAh g−1.•Ethyl cellulose enables strong ...adhesion of silicon nanoparticles on graphite.•Pitch coating improves electrical conductivity and stability of composite particles.•Pitch coated composites retain >70% of specific capacity after 400 cycles.
Composites consisting of graphite and silicon have been considered as potential high-capacity anode materials for the next-generation Li-ion batteries (LIBs). The synthesis method is critical for determining the microstructure, which is directly related to the material performance and the cost-efficiency for making commercial electrode materials. Herein, we report the fabrication of silicon-on-graphite (Si@Gr) composites by fluidized bed granulation (FBG) for the first time. The FBG process is shown to produce composite powders comprising a uniform layer of nano-sized Si particles lodged onto the surface of micron-sized graphite particles to possess a core-shell microstructure. Adopting a suitable binder during the FBG process enables a firm adhesion of the Si nanoparticles on graphite surface during subsequent carbon-coating, where the composite particles are coated with pitch and then carbonised to form a highly electronically conductive and mechanical stabilizing layer of amorphous carbon. These carbon-coated composites exhibit a high capacity reaching over 600 mAh g−1, high rate capability and illustrates the potential of long-cycle stability in Si@Gr || Li metal cells, showing more than 70% capacity retention after 400 charge-discharge cycles even without electrolyte optimization. Furthermore, a significantly improved cycling stability is found for the carbon-coated Si@Gr materials in LiNi0.6Co0.2Mn0.2O2 (NCM-622) || Si@Gr full-cells.
Brookite TiO2 mesocrystals were synthesized for the first time using amorphous titanate used as a precursor, exhibiting a high rate capability when applied as an anode for lithium-ion batteries. An ...in situ X-ray diffraction test of lithium intercalation into the brookite TiO2 structure was further investigated and revealed a reversible phase transformation.
Innocuous hydrogels with the characteristics of high conductivity, stretchability and air-stability have potential applications for emerging wearable and bio-related electronic devices. In this ...study, we develop a rapid and green method for stretchable supercapcitors using safer chemicals to produce hygroscopic conductive polymer hydrogels, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/poly(vinyl alcohol)/poly(methacrylic acid) (PEDOT:PSS/PVA/PMAA). The as-fabricated conductive polymer hydrogels show a high stretchability as well as a high conductivity (3.1 S cm−1) after absorbing water moisture as the plasticizer, which are used as current collectors and electrode materials to assemble the supercapacitor. By modulating the PEDOT: PSS composition in the hydrogel, the fabricated supercapacitor exhibits fascinating mechanical properties and excellent electrochemical characteristics. The supercapacitor has a maximum specific capacitance of 7.38 mF cm−2 at 10 mV/s, and shows 82% capacitance retention over 2000 charge-discharge electrochemical cycling testing at a current density of 10 mA cm−2. More importantly, the device could be stretched up to 100% strain without affecting the electrochemical performance and is well conserved after stretching 1000 times under 30% tensile strain.
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•Conductive polymer hydrogels prepared by a rapid and green method.•Stretchable hydrogels showed a high conductivity after absorbing water.•Highly stretchable supercapacitor exhibited a large areal specific capacitance.•Supercapacitor conserved after stretching 1000 times under 30% tensile strain.
