Sulfate-Based Cathode Materials for Li- and Na-Ion Batteries.

Electrochemical energy storage via Li-ion batteries has changed modern life drastically and has enabled technologies such as portable electronic devices, electric vehicles and stationary grid storage. However, with the steadfast technological evolution and increasing energy demands, batteries need to be constantly improved to meet the needs of our society. Furthermore, increasing concerns are raised regarding sustainability, availability of raw materials and cost. Therefore, extensive research efforts have been focused on the development of new battery types leading to the emergence of the Na-ion technology and the discovery of a myriad of new materials. In this context, polyanions became a prominent alternative to layered oxides. A large variety of polyanionic frameworks has been studied in the past years including phosphates, silicates and borates, but it was especially sulfates, which attracted a lot of attention due to their elevated operating voltages. The here presented article gives an overview of the exhaustive research on sulfate-based cathode materials for Li- and Na-ion batteries discussing recent findings and future perspectives.