Flexible, Self‐Supported Anode for Organic Batteries with a Matched Hierarchical Current Collector System for Boosted Current Density. Issue 50 (14th October 2021)

• Record Type: Journal Article
• Authors: Beladi‐Mousavi, Seyyed Mohsen; Klein, Jonas; Ciobanu, Marius; Sadaf, Shamaila; Mahmood, Arsalan Mado; Walder, Lorenz
• Is Part Of: Small. Volume 17:Issue 50(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-14
• Subjects: electrodeposition -- flexible batteries -- hierarchical current collector -- organic anodes -- organic batteries -- reduced graphene oxide -- viologens; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202103885
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: The inherent flexibility of redox‐active organic polymers and carbon‐based fillers, combined with flexible current collectors (CCs) is ideal for the fabrication of flexible batteries. Herein, a one‐step electrophoretic deposition of polyviologen (PV)/graphene‐oxide (GO) aqueous composites onto a flexible mesh of 60 µm thick wires, 100 µm apart, is described. Notably, during electrodeposition, GO is transformed into conductive reduced GO (rGO), and nanoscopic pores are formed by self‐assembly allowing charge/discharge of the redox sites over dozens of micrometers. Typically, electrodeposition of PV alone on a flat CC (FCC) is limited by its electrically insulating structure to ≈0.15 mAh cm −2, but the presence of rGO allows thicker active layers without loss in (dis‐)charging kinetics and reaching areal capacities of ≈2 mAh cm −2 . Remarkably, when the FCC is replaced by a mesh, the deposition of significantly more anode materials (≈5 mAh cm −2 ) is possible, while the (dis‐)charging kinetics is considerably improved. It exhibits high capacity retention at an ultrafast rate of 100 C (<3%) and excellent bending stabilities. This represents the first combination of a microscopic‐CC (mesh wires) with a molecular‐electronic and ‐ionic conductor (rGO with its pores), i.e., a hierarchical‐CC system with maximized polymer thickness and minimized wire thickness. The stacking of such modified grids paves the road to further increase the areal capacity. Abstract : Energy storage materials and current collectors with inherent flexibility are highly desired for fabrication of bendable batteries. Herein, a one‐step electrophoretic deposition of polyviologen/reduced‐graphene‐oxide composite on a flexible grid allowing deposition of ≈5 mAh cm −2 active materials is introduced. This hierarchical system not only provides an ultrafast charging–discharging rate but also demonstrates excellent cycling and bending stability.