The development of metal oxides as anodes of lithium‐ion batteries is severely limited because of their poor conductivity and serious volume expansion during the cycles. This work focuses on the improvement of electronic conductivity and cycle stability of metal oxides. The nanocubes of Prussian blue analogues are firstly encapsulated in the network of graphene aerogel (GA), and then the Co3O4@GA composites are synthesized after the subsequent calcination treatment. The resulting products are used as free‐standing and high‐performance anodes of LIBs, and the optimal electrode delivers a specific capacity of 624 mAh g−1 at 100 mA g−1 after 100 cycles together with a good cycle stability. The extraordinary lithium‐storage performances can be ascribed to the synergistic interaction between metal oxides and GA substrate. The incorporation of GA improves the electrode conductivity and alleviates the aggregation and volume expansion of metal oxide particles upon cycling, whereas cobalt oxides contribute a high specific capacity.
Metal selenides as anode materials of lithium‐ion batteries (LIBs) has received considerable attention recently. In order to boost the electronic conductivity and alleviate the volume change of electrode materials upon the cycles, a facile strategy is employed in this work, where Prussian blue analogue (PBA) nanocubes are encapsulated into three‐dimensional (3D) network of graphene aerogel (GA), followed by a high‐temperature selenization treatment to isolate the composite of FeCoSe2@GA. The composite can be directly employed as free‐standing anode materials of LIBs. Studies reveal that the FeCoSe2@GA electrode demonstrates an intriguing cycle stability and rate capability with a specific capacity of ∼500 mAh g−1 at 100 mA g−1 after 100 cycles. The outstanding lithium‐storage properties can be attributed to the 3D porous feature as well as the strong confinement effect of GA for FeCoSe2 particles, which provides a large number of ion‐exchange channels, and prevents the severe agglomeration and large volume expansion of active particles during the charge/discharge process.
Designing core‐shell heterostructures is essential for electrocatalytic hydrogen evolution reaction (HER). In this study, ultrathin MoS2 sheets are uniformly anchored on CoxP/nitrogen dual‐doped carbon nanocubes (CoxP/NC) through a template sacrificial method followed by a hydrothermal reaction. The resultant hybrid CoxP/NC@MoS2 possesses a core‐shell structure and superior catalytic activity to individual counterparts. The hybrid catalyst needs a low overpotential of 148 mV to drive the current density of 10 mA cm−2, together with an extremely small Tafel slope of 33 mV dec−1 and outstanding stability in acidic media. Most importantly, the best catalytic activity is achieved by coupling MoS2 nanosheets with the matrix CoxP/NC rather than Co/NC. The remarkably high HER activity of CoxP/NC@MoS2 mainly benefits from the core‐shell feature and strong synergistic interaction between CoxP/NC and MoS2. The present study inspires a continuous exploration of engineering MoS2 nanosheets on nanostructured metal phosphides for electrochemical applications.
Transition metal phosphides have received increasing attention in the field of lithium‐ion batteries (LIBs) due to their potential advantages in optimizing electrochemical performances. In order to improve the structural stability and electrochemical reaction kinetics of metal phosphides, it's an effective strategy for introducing foreign metal atoms to isolate bimetallic phosphides. Herein, a metal‐organic‐framework (MOF)‐templated protocol is utilized to synthesize CoFeP hollow nanorods as high‐performance LIBs anode materials. The results reveal that the substitution of Co ions enriches Fe‐based MOF‐derived structure with active sites, meanwhile the Co doping boosts the electronic conductivity. Therefore, the obtained CoFeP electrode displays a superior lithium‐storage ability to single metal phosphide (FeP), in terms of specific capacity, cycle stability, and rate capability. The reversible specific capacity of CoFeP at a current density of 0.1 A g−1 is as high as 897.2 mA h g−1, and the capacity can be still maintained at 478.5 mA h g−1 even at 1 A g−1 after 800 cycles. The intriguing LIBs performance of CoFeP is mainly ascribed to the collaborative contribution of hollow structure and Co doping.
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