Resolving the sluggish transport kinetics of divalent Zn 2+ in the cathode lattice and improving mass-loading performance are crucial for advancing the zinc-ion batteries (AZIBs) application. Herein, PEO-LiV 3 O 8 superlattice nanosheets (PEO-LVO) with expanded interlayer spacing (1.16 nm) are fabricated to provide a high-rate, stable lifetime, and large mass-loading cathode. The steady in-plane expansion without shrinkage after the first cycle, but reversible H + /Zn 2+ co-insertion in PEO-LVO are demonstrated by operando synchrotron X-ray diffraction and ex situ characterizations. Moreover, the large capacity of PEO-LVO is traced back to the optimized Zn 2+ insertion chemistry with increased Zn 2+ storage ratio, which is facilitated by the interlayer PEO in lowering the Zn 2+ diffusion barrier and increased number of active sites from additional interfaces, as anticipated by density functional theory. Due to the optimized ion insertion resulting in stalled interfacial byproducts and rapid kinetics, PEO-LVO achieves excellent high mass-loading performance (areal capacity up to 6.18 mAh cm −2 for freestanding electrode with 24 mg cm −2 mass-loading and 2.8 mAh cm −2 at 130 mA cm −2 for conventional electrode with 27 mg cm −2 mass-loading). As a proof-of-concept, the flexible all-solid-state fiber-shaped AZIBs with high mass-loading woven into a fabric can power an electronic watch, highlighting the application potential of PEO-LVO cathode.
Following the rapid development of wearable technology , fiber-shaped energy storage systems integrating the merits of being lightweight and flexible are receiving unprecedented attention. Meanwhile, considering the increasing concerns for the scarcity of lithium (Li) resources, research on rechargeable batteries that use sodium (Na) as the shuttling ion is rapidly growing. As yet, there have been very few successful demonstrations of fiber-shaped Na-ion batteries, probably due to the lack of mechanically stable electrodes that can sustain the insertion of large-sized Na ions . Herein, by stacking giant two-dimensional sheet forms of an electrochemically active material, titania, along with reduced graphene oxide (rGO), into a belt-shape and placing one-dimensional carbon nanotubes (CNTs) sporadically between the neighboring sheets, a fiber electrode with decent Na-ion storage performance was successfully obtained. Benefiting from the conformal stacking of the electrochemically active and charge-collecting components, the fiber electrode did not require any conducting backbones, and thus exhibited outstandingly robust integrity. The incorporation of CNTs with a differing dimension disordered the stacking structure, which opened up paths for Na-ion intercalation, thus enabling exceptionally long-term reversible Na-ion intercalation/deintercalation, even under bending conditions. This work developed a new paradigm toward designing novel fiber electrodes that can host large alkaline ions for use in future flexible and portable electronic devices.
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