Freestanding Potassium Vanadate/Carbon Nanotube Films for Ultralong-Life Aqueous Zinc-Ion Batteries

Abstract

Among various energy storage devices, aqueous zinc-ion batteries (ZIBs) have captured great attention due to their high safety and low cost. One of the most promising cathodes of aqueous ZIBs is layered vanadium-based compounds. However, they often suffer from the capacity decaying during cycling. Herein, we prepared KV3O8·0.75H2O (KVO) and further incorporated it into a single-walled carbon nanotube (SWCNT) network, achieving freestanding KVO/SWCNT composite films. The KVO/SWCNT cathodes exhibit a Zn2+/H+ insertion/extraction mechanism, resulting in fast kinetics of ion transfer. In addition, the KVO/SWCNT composite films possess a segregated network structure, which offers the fast kinetics of electron transfer and guarantees an intimate contact between KVO and SWCNTs during cycling. As a result, the resultant batteries deliver a high capacity of 379 mAh g–1, excellent rate capability, and an ultralong cycle life up to 10,000 cycles with a high capacity retention of 91%. In addition, owing to the high conductivity and flexibility of KVO/SWCNT films, flexible soft-packaged ZIBs based on KVO/SWCNT film cathodes were assembled and displayed stable electrochemical performance at different bending states.

Electrolyte Concentration Regulation Boosting Zinc Storage Stability of High-Capacity K0.486V2O5 Cathode for Bendable Quasi-Solid-State Zinc Ion Batteries

“…When charged to 1.65 V, the (001) peak gradually returns back to the original position with the disappearance of Zn 5 (OH) 8 Cl 2 ·H 2 O signals, indicative of good Zn 2+ /H + insertion/deinsertion reversibility. All these results are in good agreement with previous reports on other vanadate cathodes [ 18 , 35 ]. The XPS analysis was further used to investigate the valence change of V in KVO during the discharge/charge process (Fig.…”

“…3 d. In general, no detectable phase change can be observed for the KVO cathode. During the discharge process from 1.65 to 0 V, the diffraction peak related to (001) facets at 9.3° of KVO gradually shifts toward higher angles, resulting from the decrease of interlayer spacing caused by the Zn 2+ insertion [ 35 ] (attracting the negatively charged V–O slabs). Meanwhile, a new XRD peak at 11.2° is observed, which can be indexed to Zn 5 (OH) 8 Cl 2 ·H 2 O (JCPDS No.…”

“…2g-j) further demonstrates the homogenous distribution of K in the KVO nanowire, indicating that K ions have been successfully incorporated into the layered structure. [18,35]. The XPS analysis was further used to investigate the valence change of V in KVO during the discharge/charge process (Fig.…”

The Current Developments and Perspectives of V2O5 as Cathode for Rechargeable Aqueous Zinc‐Ion Batteries

“…[ 103 ] Therefore, the development of flexible zinc ion batteries (F‐ZIBs) is promising application in daily life and received extra attention. [ 21,104,105 ] F‐ZIBs are generally composed of cathode, anode, current collector, electrolyte, separator, and others (such as packaging materials, Figure 8 a) and all these parts must have good ability to withstand deformation for high requirements on mechanical properties and it must maintain highly reversible electrochemical performance during this process. The structure of common F‐ZIBs usually includes two types of sandwich type (Figure 8b) and cable type (Figure 8c–e).…”

Aqueous Rechargeable Zn‐ion Batteries: Strategies for Improving the Energy Storage Performance

“…Carbonaceous materials have also been used to improve the overall conductivity and hence the cycling performance and rate capability of vanadium-based ZIBs. [69,[220][221][222][223][224]…”