The LiVO Superlattice Cathode with Optimized Zinc Ion Insertion Chemistry for High Mass-Loading Aqueous Zinc-Ion Batteries.

Resolving the sluggish transport kinetics of divalent Zn in the cathode lattice and improving mass-loading performance are crucial for advancing the zinc-ion batteries (AZIBs) application. Herein, PEO-LiVO 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 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 insertion chemistry with increased Zn storage ratio, which is facilitated by the interlayer PEO in lowering the Zn 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 for freestanding electrode with 24 mg cm mass-loading and 2.8 mAh cm at 130 mA cm for conventional electrode with 27 mg cm 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.