The renewable energy sector constantly requires new and inventive grid storage solutions to meet the growing demand. It is particularly important to handle the strain on the electrical grid caused by the diurnal shift from peak energy production to peak energy demand. Although lithium-ion technology is currently the most advanced battery technology, it has significant drawbacks, including high cost, material supply risks, and low sustainability. These drawbacks have directed significant attention towards alternative battery technologies in the scientific community today. Among these alternatives, the most promising one currently is the sodium ion battery (SIB), which is chemically similar to lithium ion batteries. While commercial SIB products are beginning to emerge and are announced to be utilized in even electric vehicles, they have yet to match the performance of lithium ion batteries in terms of gravimetric or volumetric energy density. Nonetheless, the main driving force behind the development of high-performance sodium ion batteries is the desire to avoid escalating costs and supply risks associated with the limited availability of resources. As a result, sodium ion battery development is primarily focused on applications in large-scale grid storage, where sacrificing energy density for lower costs or longer battery life is more acceptable. Since the discovery of hard carbon (nongraphitizable carbon) as a suitable anode material for sodium ion insertion, the cathode material has become the bottleneck of SIB development. In this regard, materials based on Prussian blue (PB, A 0-2 Fe[Fe(CN) 6 ]) and their analogues (PBA, A 0-2 B[B ' (CN) 6 ])) are a highly suitable cathode candidate for a sustainable grid storage solution utilizing SIBs. These materials offer a combination of long cycle life, high rate capability, and abundant elements, resulting in low material costs and no supply risk, even in the long run. This advantage is particularly prominent in the historically longest-known Prussian blue variant, where iron atoms occupy both transition metal (TM) sites.