Search

Aqueous zinc-ion batteries (AZIBs) have great potential in the field of stationary energy storage due to their low manufacturing cost and high safety. However, the zinc dendrite growth arising from the uneven deposition of zinc ions has been inhibiting the application of AZIBs. In this work, hydrophilic and nanocrystalline carbon quantum dots (CQDs) are synthesized and used as electrolyte additives to improve the dendrite issue. The abundant hydrophilic groups on CQDs are favorable for homogeneous Zn deposition, whereas the improved conductivity due to the high graphitization of CQDs reduces the solid-electrolyte interface impedance and lowers the polarization voltage, resulting in better rate capability of Zn-ion batteries. Owing to the reduced energy barrier of Zn2+ nucleation and the enhanced kinetics of Zn2+ plating/stripping derived from the hydrophilic and nanocrystalline CQDs, the Zn//Zn symmetrical batteries with CQDs can operate stably for more than 1000 h at 1 mA cm−2 and 1 mA h cm−2, and show superior rate performance with low voltage hysteresis of 98.3, 120.5, 156.4, and 210.2 mV at current densities of 1, 2, 3 and 4 mA cm−2. Moreover, Zn//Cu half-cells with CQDs achieve a high average coulombic efficiency of 99.7% at 1 mA cm−2 and 0.5 mA h cm−2, and Zn//MnO2 full batteries can be cycled more than 500 times with a capacity retention of 74%. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have become one of the most potential energy storage devices due to their high safety and low cost. Vanadium oxide is an ideal cathode material for AZIBs because of its unique tunnel structure and multivalent nature. In this work, electrospun VO 2 /carbon fibers (VO 2 @CPAN) with a three-dimensional (3D) network are obtained by an electrospinning strategy combining with a controlled heat treatment. As cathode for AZIBs, the 3D network of the carbon fiber significantly improves the conductivity of VO 2 , avoids the agglomeration of VO 2 , and increases the stability of VO 2 . Therefore, VO 2 @CPAN delivers a specific capacity of 323.2 mA h g -1 at 0.2 A g -1 , which is higher than pure VO 2 . At the same time, excellent capacity retention of 76.6% is obtained at high current density of 10 A g -1 after 3000 cycles., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)