Bamboo‐Like Hollow Tubes with MoS₂/N‐Doped‐C Interfaces Boost Potassium‐Ion Storage

Abstract

Potassium-ion batteries (KIBs) are new-concept of low-cost secondary batteries, but the sluggish kinetics and huge volume expansion during cycling, both rooted in the size of large K ions, lead to poor electrochemical behavior. Here, a bamboo-like MoS 2 /N-doped-C hollow tubes are presented with an expanded interlayer distance of 10 Å as a high-capacity and stable anode material for KIBs. The bamboo-like structure provides gaps along axial direction in addition to inner cylinder hollow space to mitigate the strains in both radial and vertical directions that ultimately leads to a high structural integrity for stable long-term cycling. Apart from being a constituent of the interstratified structure the N-doped-C layers weave a cage to hold the potassiation products (polysulfide and the Mo nanoparticles) together, thereby effectively hindering the continuing growth of solid electrolyte interphase in the interior of particles. The density functional theory calculations prove that the MoS 2 /N-doped-C atomic interface can provide an additional attraction toward potassium ion. As a result, it delivers a high capacity at a low current density (330 mAh g −1 at 50 mA g −1 after 50 cycles) and a high-capacity retention at a high current density (151 mAh g −1 at 500 mA g −1 after 1000 cycles).

Mosaic Red Phosphorus/MoS2 Hybrid as an Anode to Boost Potassium‐Ion Storage

“…In the first cathodic scan, two cathodic peaks were observed at ∼0.24 and 0.85 V. However, these two reduction peaks disappeared in subsequent scans, which could be resulted from the formation of solid electrolyte interphase (SEI) and the structural change to accommodate the insertion of K + . The wide cathodic peak at ∼0.7–1.2 V is ascribed to K + insertion into MoS 2 interlayer (MoS 2 +x K + +x e − ⇆K x MoS 2 ) and the potassiation of RP . Meanwhile, the oxidation peak at ∼1.5–1.8 V reveals the depotassiation process .…”

Heterostructures of 2D Molybdenum Dichalcogenide on 2D Nitrogen‐Doped Carbon: Superior Potassium‐Ion Storage and Insight into Potassium Storage Mechanism

“…[ 19–21 ] Among these TMDs, MoS 2 and MoSe 2 have been regarded as the most promising electrode materials for KIBs because of the high theoretical capacity and unique 2D layer structure. [ 22–26 ] However, the MoS 2 or MoSe 2 as anodes for KIBs have rarely been reported because of the poor electrochemical performance due to the slow reaction kinetic and the huge volume expansion during K + intercalation. [ 27 ] Consequently, it is urgent to develop advanced MoS 2 (MoSe 2 )‐based electrode materials for KIBs by rational component optimization and interfacial modification.…”

“…[ 23 ] The K 0.4 MoS 2 possesses the same hexagonal structure as MoS 2 , but the d ‐spacing is expanded from 0.64 to 0.83 nm because of the K + intercalation. [ 24 ] The other two peaks at 0.60 and 0.18 V correspond to the conversion of K 0.4 MoS 2 to Mo and K 2 S and the formation of SEI film on the MoS 2 ‐on‐NC surface, respectively. [ 40 ] Moreover, an oxidation peak appears at 1.50 V, which is assigned to the oxidation reaction from discharging product Mo and K 2 S to MoS 2 .…”

“…The initial Coulombic efficiency (ICE) is low, which is mostly attributed to the formation of SEI layer derived from the side reactions of electrolyte on the MoS 2 ‐on‐NC surface. [ 24,40 ] After 240 cycles the MoS 2 ‐on‐NC can still keep a capacity of 453 mAh g −1 . However, the capacities of the MoS 2 /NC and the MoS 2 nanosheets decay to 75 and 141 mAh g −1 after 40 and 100 cycles, respectively.…”

Highly Concentrated KTFSI : Glyme Electrolytes for K/Bilayered‐V2O5 Batteries

“…[8,14] So far, the investigation has focused on negative electrode materials. [19,20] In fact, numerous anode materials with high stability, capacity, and rate performance have been developed, such as carbonaceous materials, [21,22] transitional-metal dichalcogenides, [23][24][25] alloy materials, [26,27] phosphides, [11,28] and organic compounds. [10,29] On the other hand, the choice of positive electrode materials for PBs is very limited due to, among other reasons, the sluggish insertion kinetics resulting from the large K + ionic radius.…”