Hybrid Nano Flake-like Vanadium Diselenide Combined on Multi-Walled Carbon Nanotube as a Binder-Free Electrode for Sodium-Ion Batteries.

As the market for electric vehicles and portable electronic devices continues to grow rapidly, sodium-ion batteries (SIBs) have emerged as energy storage systems to replace lithium-ion batteries (LIBs). However, sodium-ion is heavier and larger than lithium-ion, resulting in volume expansion and slower ion transfer. It is necessary to find suitable anode materials with high capacity and stability. In addition, wearable electronics are starting to be commercialized, requiring a binder-free electrode used in flexible batteries. In this work, we synthesized nano flake-like VSe2 using organic precursor and combined it with MWCNT as carbonaceous material. VSe2@MWCNT was mixed homogenously using sonication and fabricated film electrodes without a binder and substrate via vacuum filter. The hybrid electrode exhibited high-rate capability and stable cycling performance with a discharge capacity of 469.1 mAhg-1 after 200 cycles. Furthermore, VSe2@MWCNT exhibited coulombic efficiency of ~99.7%, indicating good cycle stability. Additionally, VSe2@MWCNT showed a predominant 85.5% of capacitive contribution at a scan rate of 1 mVs-1 in sodiation/desodiation process. These results showed that VSe2@MWCNT is a suitable anode material for flexible SIBs.