Mass-Producible, Quasi-Zero-Strain, Lattice-Water-Rich Inorganic Open-Frameworks for Ultrafast-Charging and Long-Cycling Zinc-Ion Batteries

Adv Mater. 2020 Nov;32(45):e2003592. doi: 10.1002/adma.202003592. Epub 2020 Oct 5.

Abstract

Low-cost and high-safety aqueous Zn-ion batteries are an exceptionally compelling technology for grid-scale energy storage. However, their development has been plagued by the lack of stable cathode materials allowing fast Zn2+ -ion insertion and scalable synthesis. Here, a lattice-water-rich, inorganic-open-framework (IOF) phosphovanadate cathode, which is mass-producible and delivers high capacity (228 mAh g-1 ) and energy density (193.8 Wh kg-1 or 513 Wh L-1 ), is reported. The abundant lattice waters functioning as a "charge shield" enable a low Zn2+ -migration energy barrier, (0.66 eV) even close to that of Li+ within LiFePO4 . This fast intrinsic ion-diffusion kinetics, together with nanostructure effect, allow the achievements of ultrafast charging (71% state of charge in 1.9 min) and an ultrahigh power density (7200 W kg-1 at 107 Wh kg-1 ). Equally important, the IOF exhibits a quasi-zero-strain feature (<1% lattice change upon (de)zincation), which ensures ultrahigh cycling durability (3000 cycles) and Coulombic efficiencies of 100%. The cell-level energy and power densities reach ≈90 Wh kg-1 and ≈3320 W kg-1 , far surpassing commercial lead-acid, Ni-Cd, and Ni-MH batteries. Lattice-water-rich IOFs may open up new opportunities for exploring stable and fast-charging Zn-ion batteries.

Keywords: cathodes; inorganic open-framework; ultrafast charging; zero-strain; zinc-ion batteries.