rGO/g-C3N4 and rGO/g-C3N4/CNT microspheres are synthesized through the simple ethanol-assisted spray-drying method. The ethanol, as the additive, changes the structure of the rGO/g-C3N4 or ...rGO/g-C3N4/CNT composite from sheet clusters to regular microspheres. In the microspheres, the pores formed by reduced graphene oxide (rGO), g-C3N4, and carbon nanotube (CNT) stacking provide physical confinement for lithium polysulfides (LiPSs). In addition, enriched nitrogen (N) atoms of g-C3N4 offer strong chemical adhesion to anchor LiPSs. The dual immobilization mechanism can effectively alleviate the notorious “shuttle effect” of the lithium–sulfur battery. Meanwhile, the cathode with high cyclic stability can be achieved. The rGO/g-C3N4/CNT/S cathode delivers a discharge capacity of 620 mA h g–1 after 500 cycles with a low capacity fading rate of only 0.03% per cycle at 1 C. Even, the cathode shows a retained capacity of 712 mA h g–1 over 300 cycles with a high sulfur loading (4.2 mg cm–2) at 0.2 C.
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A novel multifunctional binder (P-ppCMC) with cross-linked and porous structure is simply prepared through partially protonation and template methods for silicon anodes to accommodate the large ...volume change of silicon and to enhance the lithium-ion diffusion during the charge/discharge process. In this binder, the cross-linked structure, formed through the carboxyl and hydroxyl groups in partially protonated carboxymethyl cellulose, increases the adhesion and mechanical property of binder, buffering the volume variation of silicon during repeated cycles. The porous structure, generated via template approach, enhances the lithium-ion diffusion and tolerates the volume variation of silicon. Therefore, the P-ppCMC binder significantly improves the cycling stability and rate performance of silicon anodes. The silicon anode with P-ppCMC displays a reversible capacity of 1835 mA h g−1 after 200 cycles at a current density of 0.5 A g−1, and a rate capability of 1707 mA h g−1 at 5 A g−1. The P-ppCMC binder also effectively increases the cycling stability of tin anodes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A new binder was cross-linked by physical and chemical cross-linkers.•The new binder has self-healing property.•The new binder provides strong adhesion and promotes lithium-ion diffusion.•The new ...binder can suppress the shuttle effect of lithium-sulfur batteries.•The cycling performance of lithium-sulfur batteries is significantly improved.
One of major issues of lithium-sulfur batteries is the lithium polysulfides shuttling effect which decreases utilization of sulfur and cycling stability. Besides, low lithium-ion diffusion, causing serious polarization, limits to achieve lithium-sulfur batteries with high rate capability. Herein, a multifunctional polymer-Laponite nanocomposite binder, cross-linked by chemical and physical cross-linkers, was prepared for sulfur cathode. In this binder, the polymer and cross-linked structure can drastically increase the uniform dispersion of active materials and the adhesion property. The Laponite, a physical cross-linker, can effectively enhance the lithium-ion transfer and greatly retard the shuttle effect, leading to low polarization and high capacity at high rate. Therefore, the polymer-Laponite nanocomposite binder can significantly improve the cycling performance and high-rate capability of the electrode. The electrode with this binder exhibits a reversible capacity of 593 mAh g−1 after 500 cycles at 0.5 C, which is much higher than that of PVDF.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this work, a new effective and low-cost binder applied in porous silicon anode is designed through blending of low-cost poly(acrylic acid) (PAA) and poly(ethylene-co-vinyl acetate) (EVA) latex ...(PAA/EVA) to avoid pulverization of electrodes and loss of electronic contact because of huge volume changes during repeated charge/discharge cycles. PAA with a large number of carboxyl groups offers strong binding strength among porous silicon particles. EVA with high elastic property enhances the ductility of the PAA/EVA binder. The high-ductility PAA/EVA binder tolerates the huge silicon volume variations and keeps the electrode integrity during the charge/discharge cycle process. EVA colloids acting as host materials for electrolytes increase the electrolyte uptake of electrodes. The porous silicon electrode with the PAA/EVA binder exhibits a reversible capacity of 2120 mA h g–1 at 500 mA g–1 after 140 cycles because of the excellent ductility and lithium-ion transport properties of the PAA/EVA binder.
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Silicon (Si) is regarded as a promising negative material for Li-ion batteries (LIBs), but the poor cyclic performance limits its practical applications. Herein, we used several different ...carbonaceous materials as carbon sources to form Si/C composites, which was formed by etched Fe–Si alloys followed by mechanical ball mill mixing with carbon. It is found that the artificial graphite as the carbonaceous material can form a well-distributed mixture during the ball milling, and then uniformly coated with amorphous carbon pyrolyzed by the phenolic resin. The pore structure of Si particles can provide rapid diffusion for lithium ions, resulting in improving the electrochemical properties. The well-coated carbon layer promotes the formation of stable SEI layer on the composites surface, which is advantageous for the long cycle performance. The carbonaceous materials (artificial graphite, flake graphite and soft carbon) have remarkable influence on the electrochemical performance of Si/C composites. The silicon/graphite-artificial graphite (Si/C-AG) exhibits the best performance among these three Si/C composites. It delivers a specific capacity of 445 mAh g-1 at 0.5 A g−1 with a retention of 94% after 200 cycles. This work would be helpful with choosing suitable carbonaceous materials for the Si/C composites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An amorphous cross‐linked binder is prepared from abundant and low‐cost sodium alginate and carboxymethyl cellulose by protonation and mixing and is used to improve the electrochemical performance of ...silicon anodes in lithium‐ion batteries. The amorphous cross‐linked structure, formed by intermolecular hydrogen bonding between the functional groups in the two polymers, effectively enhances the flexibility and strength of the binder, resulting in strong adhesion between the binder and other components in the silicon anodes. Furthermore, the binder tolerates large volume changes and reduces the pulverization of silicon during the charge–discharge process. The hydrogen bonding in the binder helps to maintain the anode integrity during the volume change, leading to an excellent cycling stability and superior rate capability with a capacity of 1863 mAh g−1 at 500 mA g−1 after 150 cycles.
Binders, keepers! An amorphous cross‐linked binder formed through hydrogen bonding can effectively tolerate the volume change of silicon during the cycling process, resulting in excellent cycling performance of a silicon anode. The hydrogen bonding in the binder maintains the anode integrity during the volume change, leading to an excellent cycling stability and superior rate ability with a capacity of 1863 mAh g−1 at 500 mA g−1 after 150 cycles.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
