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

Abstract

Herein we demonstrate the fabrication of a highperformance 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.

Direct Laser Writing: From Materials Synthesis and Conversion to Electronic Device Processing

“…Additionally, lithium costs and electrolyte toxicity further hamper the application of LIB in flexible technologies. [322,[379][380][381][382][383] Thus, thin film electrode battery cells have become increasingly desirable within this context, and laser processing has been employed over the years in several tasks, from electrode cutting, annealing, or structuring. [384] Alongside electrode processing by lasers, printing technologies have also been increasingly explored in thin battery concepts, for current collectors, electrolyte, and separator printing, to avoid physical vapor deposition under vacuum of metal electrode material (e.g., aluminum and copper).…”

“…[250] In a very elegant way, Yadav et al address this issue, by assembling a flexible zinc-ion battery (ZIB) based on DLW-engineered current collectors followed by electrodeposition of active materials. [379,382] The team laser-scribed interdigitated electrodes on PI followed by the electrodeposition of vanadium oxide and zinc. The obtained aqueous rechargeable ZIB exhibited a high initial capacity of 556 mAh g −1 at a current density of 0.1 A g −1 , even after considerable mechanical deformation tests, [379] showing comparable performance with other cells reported in the literature using other synthesis and assemblies methods.…”

“…[379,382] The team laser-scribed interdigitated electrodes on PI followed by the electrodeposition of vanadium oxide and zinc. The obtained aqueous rechargeable ZIB exhibited a high initial capacity of 556 mAh g −1 at a current density of 0.1 A g −1 , even after considerable mechanical deformation tests, [379] showing comparable performance with other cells reported in the literature using other synthesis and assemblies methods. The cell exhibited a remarkable 0.0067% capacity loss per cycle over 5500 cycles at 2 A g −1 .…”

A Minireview of the Solid-State Electrolytes for Zinc Batteries

“…A gelatin/ZnSO 4 /glutaraldehyde electrolyte was designed to be employed in a novel in-plane interdigitated configuration of ZIB with the V 5 O 12 •6H 2 O cathode, which could avoid the utilization of separator, binder, and metallic current collector and greatly enhance the energy density [121]. A high capacity of 556 mAh/g was achieved at 0.1 A/g, with no noticeable difference under bending conditions, demonstrating its flexibility.…”

Electrochemically Induced Phase Transformation in Vanadium Oxide Boosts Zn-Ion Intercalation

“…Aqueous Zn-ion batteries (AZIBs) are a prospective technology for large-scale stationary energy storage because of their sustainability, safety, and high energy density. − To facilitate the commercial application of this technology, innovative cathode materials have been developed to achieve new performance benchmarks. Vanadium oxides have been widely explored as a promising cathode candidate for AZIBs because of their multiple oxidation states, diverse structures, and natural abundance. − Nonetheless, the low electronic conductivity and sluggish Zn 2+ diffusion kinetics have hampered the demonstration of vanadium oxide dominance. Despite intensive efforts (e.g., guest ion or molecule preintercalation, interfacial modification, and defect engineering) having been invested in the development of high-performance vanadium-based oxides, − these issues are still difficult to settle simultaneously, and the cycling performance is still unsatisfactory. , It is urgent for one to seek a breakthrough from a new perspective.…”