Mosaic Red Phosphorus/MoS 2 Hybrid as an Anode to Boost Potassium‐Ion Storage

PEDOT-Coated Red Phosphorus Nanosphere Anodes for Pseudocapacitive Potassium-Ion Storage

Potassium-ion batteries (KIBs) have come up as a potential alternative to lithium-ion batteries due to abundant potassium storage in the crust. Red phosphorus is a promising anode material for KIBs with abundant resources and high theoretical capacity. Nevertheless, large volume expansion, low electronic conductivity, and limited K+ charging speed in red phosphorus upon cycling have severely hindered the development of red phosphorus-based anodes. To obtain improved conductivity and structural stability, surface engineering of red phosphorus is required. Poly(3,4-ethylenedioxythiophene) (PEDOT)-coated red phosphorus nanospheres (RPNP@PEDOT) with an average diameter of 60 nm were synthesized via a facile solution-phase approach. PEDOT can relieve the volume change of red phosphorus and promote electron/ion transportation during charge-discharge cycles, which is partially corroborated by our DFT calculations. A specific capacity of 402 mAh g-1 at 0.1 A g-1 after 40 cycles, and a specific capacity of 302 mAh g-1 at 0.5 A g-1 after 275 cycles, were achieved by RPNP@PEDOT anode with a high pseudocapacitive contribution of 62%. The surface-interface engineering for the organic-inorganic composite of RPNP@PEDOT provides a novel perspective for broad applications of red phosphorus-based KIBs in fast charging occasions.

State-of-the-art anodes of potassium-ion batteries: synthesis, chemistry, and applications

The growing demand for green energy has fueled the exploration of sustainable and eco-friendly energy storage systems. To date, the primary focus has been solely on the enhancement of lithium-ion battery (LIB) technologies. Recently, the increasing demand and uneven distribution of lithium resources have prompted extensive attention toward the development of other advanced battery systems. As a promising alternative to LIBs, potassium-ion batteries (KIBs) have attracted considerable interest over the past years owing to their resource abundance, low cost, and high working voltage. Capitalizing on the significant research and technological advancements of LIBs, KIBs have undergone rapid development, especially the anode component, and diverse synthesis techniques, potassiation chemistry, and energy storage applications have been systematically investigated and proposed. In this review, the necessity of exploring superior anode materials is highlighted, and representative KIB anodes as well as various structural construction approaches are summarized. Furthermore, critical issues, challenges, and perspectives of KIB anodes are meticulously organized and presented. With a strengthened understanding of the associated potassiation chemistry, the composition and microstructural modification of KIB anodes could be significantly improved.

Bottom-Up Synthesis of MoS2 /CNTs Hollow Polyhedron with 1T/2H Hybrid Phase for Superior Potassium-Ion Storage

Enslaved to the large-size K-ions, the construction of suitable anode materials with superior and stable potassium-ion storage properties is a major challenge. 1T phase MoS₂ possesses higher conductivity, bigger interlayer distance, and more electrochemically active sites than the 2H phase, which offers intriguing benefits for energy-related applications. In this work, the 1T/2H-phase hybrid MoS₂ nanosheets are successfully anchored in the N-doped carbon nanotube hollow polyhedron (1T/2H-MoS₂ /NCNHP) by a bottom-up solvothermal method. For the synthesized 1T/2H-MoS₂ /NCNHP, the fewer-layer 1T/2H-MoS₂ nanosheets are embedded in an N-doped carbon nanotube hollow polyhedron, with an enlarged interlayer spacing of 0.96 nm. When evaluated as anode material for potassium-ion batteries, the 1T/2H-MoS₂ /NCNHP hybrid presents outstanding potassium storage performance. It delivers a high-specific capacity of 519.2 mAh g^-1 at 50 mA g^-1 and maintains 281.2 mAh g^-1 at 1 A g^-1 over 500 cycles. The good potassium-ion electrochemical performance is attributed to the rational structural design and the synergistic effect of the components. Moreover, the 1T-MoS₂ nanosheet has excellent electrical conductivity and its enlarged interlayer spacing reduces the barrier for the embedding and stripping of K ions. Finally, the practical application of the 1T/2H-MoS₂ /NCNHP electrode material is also evaluated by assembled K-ion full cells.