Mn-based Prussian blue analogues (Mn-PBAs), featuring a three-dimensional (3D) metal-organic framework and multiple redox couples, have gained wide interests in Zn-ion batteries (ZIBs). However, owing to the Jahn-Teller distortion and disproportionation reaction of Mn³⁺, these materials suffer from poor electrochemical performances and inferior structural stability. Herein, we prepare a typical high-entropy Prussian blue analogue (HE-PBA) with increased configuration entropy through integrating five transition metal elements of Mn, Co, Ni, Fe and Cu into the nitrogen-coordinated -M- lattice sites. Consequently, the HE-PBA presents enhanced uptake of Zn²⁺ with 80 mAh·g⁻¹ compared to those medium-entropy PBAs, low-entropy PBAs and conventional PBAs, which can be assigned to “cocktail” effect of multiple transition metal active redox couples. Furthermore, a phase transition process from monoclinic phase to rhombohedral phase occurs in HE-PBA cathode, resulting in a stable structure of MN₆ (M = Mn, Co, Fe, Ni, Cu) and ZnN₄ co-linked to FeC₆ through the cyanide ligands. Additionally, the advantages of entropy-driven stability are also confirmed by the calculated reduction energy and the density of states between HE-PBA and KMn[Fe(CN)₆] (KMnHCF). This work not only presents a high-performance HE-PBA cathode in ZIBs, but also introduces a novel concept of high entropy benefiting for designing advanced materials.

Lithium-iodine (Li-I₂) battery exhibits high potential to match with high-rate property and large energy density. However, problems of the system, such as evident sublimation of iodine elements, dissolution of iodine species in electrolyte, and lithium anode corrosion, prevent the practical use of rechargeable Li-I₂ batteries. In this work, a molten Li-I₂ typical cell design which has distinct advantages based on the solid-state garnet electrolyte with the eutectic iodate cathode is firstly developed. The U-shaped ceramic electrolyte tube can separate Li anode from the eutectic iodate cathode, so as to better tackle the above-mentioned inherent challenges for the liquid electrolyte systems. Without self-discharging and lithium anode corrosion, this solid-state battery system demonstrates high safety margin and excellent electrochemical performance. Also, the simple battery structure also indicates the easy assembly process and recycling of electrode materials. With the cathode loading of 593 mg in a single cell, an energy density of ~ 506.7 Wh·kg⁻¹ was achieved at 1 C and a long-term cycling life for 2,000 cycles also displays negligible capacity decay.