Although silicon is a promising anode material for lithium-ion batteries, scalable synthesis of silicon anodes with good cyclability and low electrode swelling remains a significant challenge. ...Herein, we report a scalable top-down technique to produce ant-nest-like porous silicon from magnesium-silicon alloy. The ant-nest-like porous silicon comprising three-dimensional interconnected silicon nanoligaments and bicontinuous nanopores can prevent pulverization and accommodate volume expansion during cycling resulting in negligible particle-level outward expansion. The carbon-coated porous silicon anode delivers a high capacity of 1,271 mAh g
at 2,100 mA g
with 90% capacity retention after 1,000 cycles and has a low electrode swelling of 17.8% at a high areal capacity of 5.1 mAh cm
. The full cell with the prelithiated silicon anode and Li(Ni
Co
Mn
)O
cathode boasts a high energy density of 502 Wh Kg
and 84% capacity retention after 400 cycles. This work provides insights into the rational design of alloy anodes for high-energy batteries.
Potassium-ion batteries (KIBs) are a promising alternative to lithium-ion batteries (LIBs) for large-scale renewable energy storage owning to the natural abundance and low cost of potassium. However, ...the biggest challenge for KIBs application lies in the lack of suitable electrode materials that can deliver long cycle life and high reversible capacity. In this work, we realized unprecedented long cycle life with high reversible capacity (465 mAh g–1 at 2 A g–1 after 800 cycles) as well as outstanding rate capability (342 mAh g–1 at 5 A g–1) for KIBs by embedding red P into free-standing nitrogen-doped porous hollow carbon nanofibers (red P@N-PHCNFs). This design circumvents the problems of pulverization and aggregation of P particles. The in situ transmission electron microscopy (TEM) investigation reveals the structural robustness of the composite fibers during potassiation. The formation of P–C chemical bonds as well as nitrogen doping in the carbon matrix can facilitate the sturdy contact and enhance the adsorption energy of P atoms evidenced by DFT results. In situ Raman and ex situ XRD demonstrate that the final discharge product of the red P@N-PHCNFs is K4P3.
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IJS, KILJ, NUK, PNG, UL, UM
Given the merits of low cost, fast ionic transport in electrolyte, and high operating voltage, potassium ion batteries (PIBs) are promising alternatives to lithium‐ion batteries. However, developing ...suitable electrode materials that can reversibly accommodate large potassium ions is a great challenge. Here, guided by density functional theory (DFT) calculations, it is demonstrated that the strategy of interfacial engineering via surface amorphization of VO2 (B) nanorods (SA‐VO2), which results in the formation of a crystalline core/amorphous shell heterostructure, enables superior K+ storage performance in terms of large capacity, outstanding rate capability, and long cycle stability working as an anode for PIBs. DFT calculations reveal that the created crystalline/amorphous heterointerface in SA‐VO2 can substantially lower the surface energy, narrow the band gap, and reduce the K+ diffusion barrier of VO2 (B). These conditions enable enhanced K+ storage capacity and rapid K+/electron transfer, which result in large capacity and outstanding rate capability. Using in situ X‐ray diffraction and in situ transmission electron microscopy complemented by ex situ microscopic and spectroscopic techniques, it is unveiled that the superior cycling stability originates from the excellent phase reversibility with negligible strain response and robust mechanical behavior of SA‐VO2 upon (de)potassiation.
Interfacial engineering via surface amorphization is applied to prepare VO2 nanorods (SA‐VO2) with an impressive potassium ion storage capability. Surface oxygen vacancies lower the surface energy, narrow the band gap, and reduce the K+ diffusion barrier of VO2. Various in situ studies reveal that the superior cycling stability originates from the excellent phase reversibility with negligible strain evolution of SA‐VO2 upon (de)potassiation.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The development of high-performance supercapacitors (SCs) often faces some contradictory and competing requirements such as excellent rate capability, long cycling life, and high energy density. One ...effective strategy is to explore electrode materials of high capacitance, electrode architectures of fast charge and mass transfer, and electrolytes of wide voltage window. Here we report a facile and readily scalable strategy to produce high-performance N-doped graphene with a high specific capacitance (∼390 F g−1). A symmetric SC device with a wide voltage window of 3.5 V is also successfully fabricated based on the N-doped graphene electrode. More importantly, the as-assembled symmetric SC delivers a high energy density of 55 Wh kg−1 at a power density of 1800 W kg−1 while maintaining superior cycling life (retaining 96.6% of the initial capacitance after 20,000 cycles). Even at a power density as high as 8800 W kg−1, it still retains an energy density of 29 Wh kg−1, higher than those of previously reported graphene-based symmetric SCs.
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•N-doped graphene with 3D porous architecture was successfully prepared.•The electrode delivered high specific capacitance and excellent cycling stability.•The symmetrical supercapacitor achieved a remarkable energy and power density.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Potassium‐ion batteries (PIBs) are promising alternatives to lithium‐ion batteries because of the advantage of abundant, low‐cost potassium resources. However, PIBs are facing a pivotal challenge to ...develop suitable electrode materials for efficient insertion/extraction of large‐radius potassium ions (K+). Here, a viable anode material composed of uniform, hollow porous bowl‐like hard carbon dual doped with nitrogen (N) and phosphorus (P) (denoted as N/P‐HPCB) is developed for high‐performance PIBs. With prominent merits in structure, the as‐fabricated N/P‐HPCB electrode manifests extraordinary potassium storage performance in terms of high reversible capacity (458.3 mAh g−1 after 100 cycles at 0.1 A g−1), superior rate performance (213.6 mAh g−1 at 4 A g−1), and long‐term cyclability (205.2 mAh g−1 after 1000 cycles at 2 A g−1). Density‐functional theory calculations reveal the merits of N/P dual doping in favor of facilitating the adsorption/diffusion of K+ and enhancing the electronic conductivity, guaranteeing improved capacity, and rate capability. Moreover, in situ transmission electron microscopy in conjunction with ex situ microscopy and Raman spectroscopy confirms the exceptional cycling stability originating from the excellent phase reversibility and robust structure integrity of N/P‐HPCB electrode during cycling. Overall, the findings shed light on the development of high‐performance, durable carbon anodes for advanced PIBs.
A viable anode material composed of nitrogen/phosphorus co‐doped hollow porous bowl‐like hard carbon is developed for potassium ion batteries. The resulting anode manifests prominent merits in structure, endowing it with extraordinary K+ storage capability. The K+ storage mechanisms are revealed through in‐depth studies by combining in situ TEM studies, ex situ microscopic, and Raman spectroscopy in conjunction with DFT calculations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Rechargeable metal-air batteries and water splitting are highly competitive options for a sustainable energy future, but their commercialization is hindered by the absence of cost-effective, highly ...efficient and stable catalysts for the oxygen evolution reaction. Here we report the rational design and synthesis of a double perovskite PrBa
Sr
Co
Fe
O
nanofiber as a highly efficient and robust catalyst for the oxygen evolution reaction. Co-doping of strontium and iron into PrBaCo
O
is found to be very effective in enhancing intrinsic activity (normalized by the geometrical surface area, ∼4.7 times), as validated by electrochemical measurements and first-principles calculations. Further, the nanofiber morphology enhances its mass activity remarkably (by ∼20 times) as the diameter is reduced to ∼20 nm, attributed to the increased surface area and an unexpected intrinsic activity enhancement due possibly to a favourable e
electron filling associated with partial surface reduction, as unravelled from chemical titration and electron energy-loss spectroscopy.
Mixed transition metal oxides with hierarchical, porous structures, constructed from interconnected nano-building blocks, are considered promising positive electrodes for high-performance hybrid ...supercapacitors. Here we report our findings in design, fabrication, and characterization of 3D hierarchical, porous quaternary zinc-nickel-aluminum-cobalt oxide (ZNACO) architectures assembled from well-aligned nanosheets grown directly on nickel foam using a facile and scalable chemical bath deposition process followed by calcination. When tested as a binder-free electrode in a 3-electrode configuration, the ZNACO display high specific capacity (839.2Cg−1 at 1Ag−1) and outstanding rate capability (~82% capacity retention from 1Ag−1 to 20Ag−1), superior to those of binary-component NiCo2O4 and ZnCo2O4 as well as single-component Co3O4 electrode. More remarkably, a hybrid supercapacitor consisting of an as-fabricated ZNACO positive electrode and an activated carbon negative electrode exhibits a high energy density of 72.4Whkg−1 at a power density of 533Wkg−1 while maintaining excellent cycling stability (~90% capacitance retention after 10,000 cycles at 10Ag−1), demonstrating a promising potential for development of high-performance hybrid supercapacitors. Further, the unique electrode architecture is also applicable to other electrochemical systems such as batteries, fuel cells, and membrane reactors.
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•3D hierarchical porous Zn-Ni-Al-Co oxide (ZNACO) nanosheets grown directly on Ni foam is constructed for the first time.•The resultant binder-free electrodes manifest outstanding electrochemical performances with high capacity, excellent rate capability and cycling stability.•The synergetic contribution and advantageously structural features contribute to outstanding capacitive performance.•The assembled ZNACO//AC hybrid supercapacitor achieved a remarkable energy density of 72.4Whkg−1 at a power density of 533Wkg−1.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Metal oxides and carbon-based materials are the most promising electrode materials for a wide range of low-cost and highly efficient energy storage and conversion devices. Creating unique ...nanostructures of metal oxides and carbon materials is imperative to the development of a new generation of electrodes with high energy and power density. Here we report our findings in the development of a novel graphene aerogel assisted method for preparation of metal oxide nanoparticles (NPs) derived from bulk MOFs (Co-based MOF, Co(mIM)2 (mIM = 2-methylimidazole). The presence of cobalt oxide (CoO x ) hollow NPs with a uniform size of 35 nm monodispersed in N-doped graphene aerogels (NG-A) was confirmed by microscopic analyses. The evolved structure (denoted as CoO x /NG-A) served as a robust Pt-free electrocatalyst with excellent activity for the oxygen reduction reaction (ORR) in an alkaline electrolyte solution. In addition, when Co was removed, the resulting nitrogen-rich porous carbon–graphene composite electrode (denoted as C/NG-A) displayed exceptional capacitance and rate capability in a supercapacitor. Further, this method is readily applicable to creation of functional metal oxide hollow nanoparticles on the surface of other carbon materials such as graphene and carbon nanotubes, providing a good opportunity to tune their physical or chemical activities.
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IJS, KILJ, NUK, PNG, UL, UM
Lithium (Li) metal with high theoretical capacity and low electrochemical potential is the most ideal anode for next-generation high-energy batteries. However, the practical implementation of Li ...anode has been hindered by dendritic growth and volume expansion during cycling, which results in low Coulombic efficiency (CE), short lifespan, and safety hazards. Here, we report a highly stable and dendrite-free Li metal anode by utilizing N-doped hollow porous bowl-like hard carbon/reduced graphene nanosheets (CB@rGO) hybrids as three-dimensional (3D) conductive and lithiophilic scaffold host. The lithiophilic carbon bowl (CB) mainly works as excellent guides during the Li plating process, whereas the rGO layer with high conductivity and mechanical stability maintains the integrity of the composite by confining the volume change in long-range order during cycling. Moreover, the local current density can be reduced due to the 3D conductive framework. Therefore, CB@rGO presents a low lithium metal nucleation overpotential of 18 mV, high CE of 98%, and stable cycling without obvious voltage fluctuation for over 600 cycles at a current density of 1 mA·cm
−2
. Our study not only provides a good CB@rGO host and pre-Lithiated CB@rGO composite anode electrode, but also brings a new strategy of designing 3D electrodes for those active materials suffering from severe volume expansion.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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