Bo Wang,Jianping Yan,Yufei Zhang,Minghui Ye,Yang Yang,Cheng Chao Li
Aqueous zinc-ion batteries (ZIBs) have attracted significant attention due to their intrinsic safety, cost-effectiveness, and environmental friendliness. However, the common zinc metal anode suffers from zinc dendrite formation, self-corrosion, and surface passivation, which impede the further application of aqueous ZIBs. Herein, carbon-inserted molybdenum dioxide (MoO 2 ) materials with laminated structure are designed as novel intercalation-type anodes for ZIBs by combination of interlayer engineering and in situ carbonization of aniline guest in molybdenum trioxide interlayers. The uniform dispersion of carbon layers in laminated MoO 2 not only provide fast transportation paths for electron but also strengthen the framework of MoO 2 , leading to high structural integration during high-rate cycling. Benefiting from the unique structural design, the carbon-inserted MoO 2 electrode exhibits high initial Coulombic efficiency, excellent cycling stability, and outstanding rate capability. Multiple ex situ characterizations reveal its excellent electrochemical stability is derived from reversible intercalation mechanism and ultrastable structural framework. Furthermore, the rocking-chair zinc-ion full battery assembled with the zinc pre-intercalated Na 3 V 2 (PO 4 ) 2 O 2 F cathode presents excellent stability and ultralong lifespan with a high capacity retention of 91% over 8000 cycles.
The development of durable and stable metal oxide anodes for potassium ion batteries (PIBs) has been hampered by poor electrochemical performance and ambiguous reaction mechanisms. Herein, we design and fabricate molybdenum dioxide (MoO 2 )@ N -doped porous carbon (NPC) nano-octahedrons through metal–organic frameworks derived strategy for PIBs with MoO 2 nanoparticles confined within NPC nano-octahedrons. Benefiting from the synergistic effect of nanoparticle level of MoO 2 and N -doped carbon porous nano-octahedrons, the MoO 2 @NPC electrode exhibits superior electron/ion transport kinetics, excellent structural integrity, and impressive potassium-ion storage performance with enhanced cyclic stability and high-rate capability. The density functional theory calculations and experiment test proved that MoO 2 @NPC has a higher affinity of potassium and higher conductivity than MoO 2 and N -doped carbon electrodes. Kinetics analysis revealed that surface pseudocapacitive contributions are greatly enhanced for MoO 2 @NPC nano-octahedrons. In-situ and ex-situ analysis confirmed an intercalation reaction mechanism of MoO 2 @NPC for potassium ion storage. Furthermore, the assembled MoO 2 @NPC//perylenetetracarboxylic dianhydride (PTCDA) full cell exhibits good cycling stability with 72.6 mAh g −1 retained at 100 mA g −1 over 200 cycles. Therefore, this work present here not only evidences an effective and viable structural engineering strategy for enhancing the electrochemical behavior of MoO 2 material in PIBs, but also gives a comprehensive insight of kinetic and mechanism for potassium ion interaction with metal oxide.
Ming Zhong,Xue Guo,Lingling Li,Yun-Wu Li,Kun Zhao,Hui Peng,Xiaobo Zhang
Owing to the mixed insertion and multielectron conversion reaction mechanisms, nonstoichiometric copper selenide (Cu2–xSe) has been known as a potential anode for lithium-ion batteries. However, huge volume changes during discharge and charge limit its ability for lithium-ion storage. Constructing heterophase nanocomposite uniformly distributed in the carbon network has been recognized as an effective approach to address the above issue. In this work, polyoxometalate-based metal–organic frameworks were used as the self-template to derive octahedral mesoporous carbon-coated heterophase copper selenide and molybdenum dioxide (MoO2/Cu2–xSe@C) nanocomposites, and the phase transformation of copper selenides from CuSe to Cu2–xSe can be achieved by tuning the pyrolysis temperature, thus optimizing the electrochemical performance. As a result, the optimized electrode delivers a high reversible specific capacity of 864.8 mAh g–1 at 0.2 A g–1 after 100 cycles, an excellent rate capability with a capacity of 480.9 mAh g–1 at 2.0 A g–1, and a long-term stability up to 500 cycles with a capacity decay rate per cycle of only 0.003%. Also, the reaction mechanism and structural stability after cycling were analyzed in detail.
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