In Situ Encapsulation of MoS_xSe_2–x Nanocrystals with the Synergistic Function of Anion Doping and Physical Confinement with Chemical Bonding for High-Performance Sodium/Potassium-Ion Batteries with Wide Temperature Workability

Abstract

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are envisioned as desirable candidates for the realization of future battery systems due to the advantages of their high energy and high power density. However, the construction of anode materials with excellent performance remains a challenge. Herein, few-layered molybdenum sulfide selenide (MoS x Se 2−x ) nanocrystals with a large number of anion defects triggered by both S 2− and Se 2− improve the electrical conductivity and long lifespan of Na + /K + storage. Concurrently, the unique physical confinement with the chemical bonding structure of selenide polyacrylonitrile (SePAN) fibers can mitigate the loss of active material and provide multientry active sites for Na + /K + diffusion. As a result, the MoS 0.25 Se 1.75 -SePAN electrode delivered a superior sodium-storage performance of 521 mAh g −1 for SIBs and 439 mAh g −1 for PIBs at 0.1 A g −1 . Moreover, the long-life cycling performance of the SIBs is remarkable, reaching 391 mAh g −1 over 3600 cycles at 1 A g −1 . In addition, it displays excellent feasibility in a wide working temperature range from −15 to 50 °C for SIBs. This work elucidates a new design for in situ encapsulation and the synergistic function of anion doping and confinement to construct defectrich anodes for high-performance SIBs and PIBs with wide temperature workability.

Doping Engineering in Electrode Material for Boosting the Performance of Sodium Ion Batteries

“…For example, the performance of the widely known NaTiO 2 anode of SIBs can be tuned by substituting O with other suitable anions such as F. 31 Similarly, doping in the anionic part of various alloys anode results in a significant boost of performance, e.g., doping of S 2− in anionic part of MoSe 2 results in an improvement in the electrical conductivity of material. 32 2.1.3. Multielement Doping.…”

Boosted Hydrogen Evolution via Molten Salt Synthesis of Vacancy-Rich MoSxSe2–x Electrocatalysts

“…The successful design and synthesis of MoS x Se 2– x are critical for its application on a large scale. Currently, MoS x Se 2– x is primarily produced from elemental Se using high-temperature methods such as chemical vapor deposition and chemical vapor transport, due to the unreactive nature of powdered Se. − The integration of Se into the MoS 2 lattice improves the intrinsic HER activity by modulation of the electronic structure. Nonetheless, the high-temperature synthesis often damages the defect sites that are crucial for catalytic activity, leading to suboptimal performance.…”