MOF-based quasi-solid-state electrolyte for long-life Al-Se battery

Aluminum-selenium (Al-Se) batteries, which possess a high theoretical specific capacity of 1357 mA h g−1, represent a promising energy storage technology. However, they suffer from significant attenuation of capacity and low cycle life due to the shuttle effect. To mitigate the shuttle effect induced by soluble selenium chloroaluminate compound that tends to migrate towards the negative electrode, a quasi-solid-state Al-Se battery was fabricated through the synthesis of a multi-aperture structure quasi-solid-state electrolyte (MOF@GPE) based on metal–organic framework (MOF) material and gel-polymer electrolyte (GPE). The high ionic conductivity (1.13 × 10−3 S cm−1) of MOF@GPE at room temperature, coupled with its wide electrochemical stability window (2.45 V), can facilitate ion transport kinetics and enhance the electrochemical performance of Al-Se batteries. The MOF@GPE-based quasi-solid-state Al-Se batteries exhibit outstanding long-life cycling stability, delivering a high specific discharge capacity of 548 mA h g−1 with a maintained discharge specific capacity of 345 mA h g−1 after 500 cycles at a current density of 200 mA g−1. The stable ion transmission and high ion transport kinetics in MOF@GPE can be attributed to the stable structure and permeable channel of MOF, which effectively captures the soluble selenium chloroaluminate compound and further restrains the shuttle effect, resulting in improved cycling performance.