Fabrication of an Energy-Dense, Binder-Free Zn//V₅O₁₂·6H₂O Solid-State In-Plane Flexible Battery via a Rapid and Scalable Approach

Herein we demonstrate the fabrication of a high-performance rechargeable zinc ion battery based on a laser-scribed carbon (LSC)-supported electrodeposited zinc anode and vanadium oxide (V 5 O 12 ·6H 2 O) cathode with a planar-interdigitated electrode architecture and a polymeric solid electrolyte. This is the first report on a full-cell Zn//V 5 O 12 ·6H 2 O planar flexible battery where a practical zinc loading (∼76 times that of the cathode loading) is maintained. The electrodeposited Zn@LSC anode showed excellent stability with very low polarization over the tested 500 h (750 cycles). We demonstrate a high initial capacity of 325 mAh/g for the Zn//V 5 O 12 ·6H 2 O planar battery at 2 A/g in a 3 M ZnSO 4 aqueous electrolyte. However, the capacity dropped to 70 mAh/g only after 1000 cycles. Nonetheless, the cell performance, in particular the cycle stability, was significantly improved when the aqueous electrolyte was replaced with a gelatin/ZnSO 4 /glutaraldehyde-based solid-state electrolyte. The solid-state planar battery showed a high initial capacity of 556 mAh/g at 0.1 A/g current corresponding to an energy density of 381 Wh/kg active cathode and an impressive cycle stability with only 0.0067% capacity loss per cycle over 5500 cycles at 2 A/g. The cell also demonstrated excellent flexibility with comparable specific capacity under different bending conditions. The solid-state device exhibited a high areal energy density of 72 and 14 μWh/cm 2 at the corresponding areal power density of 130 and 2511 μW/cm 2, respectively. Overall, the rapid (complete device fabrication in ∼2 h) and scalable fabrication approach, high performance with excellent safety features, and accompanying high flexibility make the as-fabricated Zn//V 5 O 12 ·6H 2 O planar flexible battery suitable for next-generation flexible electronics applications.