Rare earth pillars for stable layered birnessite cathodes propelling aqueous zinc-ion batteries with ultra-long cyclability†

Abstract

The weak structural stability, low intrinsic conductivity, and strong electrostatic interaction of cathode materials are still bottlenecks in aqueous zinc-ion batteries. Herein, a novel win–win strategy was proposed to fabricate a yttrium ion pre-intercalated birnessite-MnO₂ cathode material. Benefiting from the unique advantages of rare earth ions with large radii, it could serve as an interlayer pillar in the crystal lattice to stabilize the structure and enhance ionic conductivity. Furthermore, the high valence state of rare earth ions could significantly weaken the electrostatic interaction between zinc ions and host structures, thereby reducing charge transfer resistance and promoting ion transport. As a result, Y_0.04K_0.16Mn₂O₄·2.3H₂O exhibits an ultra-long cycling stability of 24 000 cycles at a high current density of 8 A g⁻¹, and the average capacity decay rate is only 0.002% per cycle. This work paves the way for the application of rare earth elements in energy storage.