How Prussian Blue Analogues Can Be Stable inConcentrated Aqueous Electrolytes

Prussian blue analogues (PBAs) are promising candidates forstoring various ions in aqueous electrolytes. But they often suffer from metal-iondissolution induced structural degradation, resulting in fast capacity fade and shortcycle life. Long-term cycling of PBAs has recently been successfully demonstratedby using highly concentrated aqueous electrolytes, while the stabilizationmechanism of PBAs in the electrolytes has remained unclear. In this work, theexperimental and molecular modeling evidence indicates that the hydrophobiclayer on the PBA/electrolyte interface and the highly restricted network in theconcentrated aqueous electrolyte both play critical roles in suppressing metal-iondissolution of PBAs. That explains why the NH4+full battery consisting of a PBAcathode can be stably cycled over 4000 cycles with 72.3% capacity retention (8C).The molecular-level understanding of the stabilization mechanism establishes aguiding principle for the stable storage of diverse ions in PBAs, including but notlimited to NH4+,Li+,Na+,Mg2+, etc

Automated summary

The hydrophobic layer on the PBA/electrolyte interface and the highly restricted network in the concentrated aqueous electrolyte both play critical roles in suppressing metal-ion dissolution of PBAs.