We employ a sulfur-assisted decomposition process to create agglomerates of large (200−500 nm) yet highly nanoporous threedimensional MoO 2 single crystals partially covered with a few atomic layers of MoS 2 ("MoS 2 /MoO 2 nanonetworks"). These materials are highly promising as lithium ion battery anodes. At a current density of 100 mA g −1 , the MoS 2 /MoO 2 nanonetworks exhibit a reversible discharge specific capacity of 1233 mAh g −1 , with only 5% degradation after 80 full charge/discharge cycles. Moreover at the relatively fast discharging rates of 200 and 500 mA g −1 , the capacities are 1158 and 826 mAh g −1 , respectively. A comparison with literature shows that these are among the more promising reversible capacity, cycling capacity, and rate capability values reported for MoO 2 . The electrochemical properties are attributed to the material's nanoporous crystal morphology that allows for facile reversible transport of Li ions without either disintegration or agglomeration of the structure.

Molybdenum disulfide (MoS2), a 2D‐layered compound, is regarded as a promising anode for sodium‐ion batteries (SIBs) due to its attractive theoretical capacity and low cost. The main challenges associated with MoS2 are the low rate capability suffering from the sluggish kinetics of Na+ intercalation and the poor cycling stability owning to the stack of MoS2 sheets. In this work, a unique architecture of bundled defect‐rich MoS2 (BD‐MoS2) that consists of MoS2 with large vacancies bundled by ultrathin MoO3 is achieved via a facile quenching process. When employed as anode for a SIB, the BD‐MoS2 electrode exhibits an ultrafast charge/discharge due to the pseudocapacitive‐controlled Na+ storage mechanism in it. Further experimental and theoretical calculations show that Na+ is able to cross the MoS2 layer by vacancies, not only limited to diffusion along the layer, thus realizing a 3D Na+ diffusion with faster kinetics. Meanwhile, the bundling architecture reduces the stack of sheets with a superior cycle life illustrating the highly reversible capacities of 350 and 272 mAh g−1 at 2 and 5 A g−1 after 1000 cycles.

Capacitive storage has been considered as one type of Li-ion storage with fast faradaic surface redox reactions to offer high power density for electrochemical applications. However, it is often limited by low extent of energy contribution during the charge/discharge process, providing insufficient influences to total capacity of Li-ion storage in electrodes. In this work, we demonstrate a pseudocapacitance predominated storage (contributes 82% of the total capacity) from an in-situ pulverization process of FeOOH rods on rGO (reduced graphene oxide) sheets for the first time. Such high extent of pseudocapacitive storage in the FeOOH/rGO electrode achieves high energy density with superior cycling performance over 200 cycles at different current densities (1135 mAh/g at 1 A/g and 783 mAh/g at 5 A/g). It is further revealed that the in-situ pulverization process is essential for the high pseudocapacitance in this electrode, because it not only produces a porous structure for high exposure of tiny FeOOH crystallites to electrolyte but also maintains stable electrochemical contact during ultrahigh rate charge transfer with high energy density in the battery. The utilization of in-situ pulverization in an Fe-based anode to realize high surface pseudocapacitance with superior performance may inspire future design of electrode structures in Li-ion batteries.

The potassium‐ion battery (PIB) is an attractive energy storage device that possesses the potential advantages of high energy density and low cost. Herein, a pure 1T‐MoS2 is synthesized on graphene oxide and assembled into a hydrogel. The hydrogel is further tightened to a compact 1T‐MoS2/graphene (CTMG) bulk by a densifying strategy of capillary tension. When employed as an anode for PIBs, the CTMG electrode can store K+ through reversible intercalation and conversion electrochemistry, accompanied with fast kinetics since the 1T‐MoS2 induces a pseudocapacitive storage mechanism and the extraordinary K+ transportation ability. Consequently, the CTMG electrode delivers the high and reversible rate capacities of 511 and 327 mAh g‐1 at 0.1 and 1 A g‐1, respectively. Moreover, the compact architecture reduces the electrode thickness by ≈33% enabling a high volumetric capacity (512 mAh cm‐3 at 0.1 A g‐1 after 100 cycles), as well as holding a promising application in thick electrode.