RESUMEN
Currently, the durability of electrode materials remains a big obstacle to the widespread adoption of proton exchange membrane fuel cells (PEMFCs). Herein thiourea and sodium dodecyl benzene sulfonate (SDS) were employed as sulfur source and carbon source to modify the pristine carbon black (Ketjen black EC300â J). A highly durable carbon supported Pt nanosized catalyst with higher platinum utilization for oxygen reduction reaction (ORR) in PEMFCs was produced by doping elemental sulfur into carbon supports and decreasing the carbon pore sizes and volume through a successive impregnation technique. The catalyst exhibits an initial activity of 0.167â A mgPt -1 at 0.90â V and demonstrates minimal activity loss after acceleration stress test (30,000 cycles of AST). The half-wave potential loss for representative sample (Pt/S-C-3) is only 14â mV with only 21.8 % ECSA decrease, 27.5 % MA loss and 5.9 % SA loss. A sintering test at various temperature shows a minor average size increase for sulfur-doped carbon (S-C) supported one (from 2.09 to 2.52â nm). In single-cell test, the MEA sample employing the platinum catalyst on modified carbon as cathode exhibited almost negligible performance loss after 30,000 cycles of AST.
RESUMEN
Recently, rock-salt NiCoO2 (NCO) with desirable electronic conductivity has drawn enormous interest worldwide for energy-related applications. However, the intrinsically sluggish kinetics and electrode aggregation/volumetric change/pulverization during Li-insertion/-extraction processes hugely limit its applications in Li-ion batteries (LIBs). In the contribution, we first devise a bottom-up method for scalable fabrication of the nanodimensional NCO particles encapsulated in porous nitrogen-doped carbon submicrospheres (NCS), which are derived from a bimetal (Ni, Co) metal-organic framework. The porous NCS, as a flexible conductive skeleton, can buffer distinct volume expansion as an efficient buffering phase, restrain agglomeration of nanoscaled NCO, and enhance electronic conductivity and wettability of the electrode. Benefiting from the synergistic functions between the nanodimensional NCO and porous NCS, the obtained NCO@NCS anode (â¼74.5 wt % NCO) is endowed with remarkable high-rate reversible capacity (â¼403.0 mAh g-1 at 1.0 A g-1) and cycling behaviors (â¼371.4 mAh g-1 after being cycled for 1000 times at 1.0 A g-1) along with a high lithium diffusion coefficient and remarkable pseudocapacitive contribution. Furthermore, the NCO@NCS-based full LIBs exhibit competitive lithium-storage properties in terms of energy density (â¼217.0 Wh kg-1) and cyclic stability. Furthermore, we believe that the methodology is highly promising in versatile design and construction of binary metal oxide/carbon hybrid anodes for advanced LIBs.
RESUMEN
The exploration of anode materials with a high degree of electrochemical utilization for Li-ion batteries (LIBs) still remains a huge challenge despite pioneering breakthroughs. Rational engineering of electrode structures/components by facile strategies would offer infinite possibilities for the development of LIBs. In this study, one-dimensional ultralong nanohybrids of ultrafine NiCoO2 nanoparticles dispersed in situ in and/or on the surface of amorphous N-doped carbon nanofibers (NCO@ANCNFs) were fabricated by a bottom-up electrospinning protocol. By virtue of synergistic structural/component features, the obtained ultralong NCO@ANCNFs with low NCO loading (≈33.6â wt %) show highly efficient Li+ storage performance with high reversible capacity, high rate capability, and long cycle life. The unusual reversible crystalline transformation during cycling was analyzed. Quantitative analysis revealed that the pseudocapacitive contribution mainly accounts for the superior lithium storage of the NCO@ANCNFs. Besides, the ability of the hybrid anode to deliver competitive Li-storage properties even without conductive carbon greatly enhances its commercial applicability. An NCO@ANCNFs//LiNi0.8 Co0.15 Al0.05 O2 full battery was assembled and exhibited striking electrochemical properties. This contribution offers a scalable methodology to fabricate highly efficient hybrid anodes for advanced next-generation LIBs.
RESUMEN
Cost-efficient carbonaceous materials have been utilized extensively for advanced electrochemical supercapacitors. However, modest gravimetric/volumetric capacitances are the insuperable bottleneck in their practical applications. Herein, we develop a simple yet scalable method to fabricate low-cost micro-/mesoporous N/O-enriched carbon (NOC-K) by using natural rose multiflora as a precursor with KOH activation. The biomass-derived NOC-K is endowed with a large surface area of â¼1646.7 m2 g-1, micro-/mesoporosity with â¼61.3% microporosity, high surface wettability, and a high content of N (â¼1.2 at%)/O (â¼26.7 at%) species. When evaluated as an electroactive material for supercapacitors, the NOC-K electrode (5 mg cm-2) yields large gravimetric/volumetric specific capacitances of â¼340.0 F g-1 (â¼238.0 F cm-3) at 0.5 A g-1, and even â¼200.0 F g-1 (â¼140.0 F cm-3) at 5.0 A g-1, a low capacitance decay of â¼4.2% after 8200 consecutive cycles, and a striking specific energy of â¼8.3 W h kg-1 in aqueous KOH electrolyte, benefiting from its intrinsic structural and compositional superiorities. Moreover, a remarkable specific energy of â¼52.6 W h kg-1 and â¼96.6% capacitance retention over 6500 cycles for the NOC-K based symmetric cell are obtained with the organic electrolyte. More promisingly, the competitive NOC-K demonstrates enormous potential towards advanced supercapacitors both with aqueous and organic electrolytes as a sustainable electrode candidate.