Surface engineered terephthalic acid-ligated antimony metal-organic framework nanocubes as high-performance negatrodes for Na⁺/Li⁺ pouch full batteries

Metal–organic framework (MOF)-derived negatrodes offer significant advantages for sodium–ion (SIB) and lithium–ion (LIB) batteries due to their high gravimetric and volumetric capacities, as well as their low sodiation and lithiation potentials. However, the requirement for post-synthetic high-temperature carbonization treatments hinders their commercialization. In this work, we introduce a simple low-temperature surface-phosphatization strategy for surface-engineering terephthalic acid-derived antimony (Sb) MOF nanocubes as negatrodes in SIB and LIB pouch-type full batteries, effectively bypassing the need for high-temperature carbonization. The surface-phosphatized nanocubes deliver reversible capacities of 567 and 692 mAh·g⁻¹ for SIBs and LIBs, respectively (based on Sb content), in 4.5 cm × 3 cm pouch batteries. After 400 cycles at ∼ 0.15C, they retain 502 and 612 mAh·g⁻¹, respectively. In terms of scalability, the corresponding 13.5 cm² pouch-type full batteries (with compatible cathodes) deliver 4.22 mAh (312.7 µAh∙cm⁻²) and 11.1 mAh (822.3 µAh∙cm⁻²) in SIB and LIB formats, respectively. Based on gross weight of the SIB and LIB pouch batteries, the energy densities were estimated to be 20.37 Wh∙kg⁻¹ (SIB) and 66.17 Wh∙kg⁻¹ (LIB), respectively. Detailed structural and electrochemical testing confirm that this surface-phosphatization strategy significantly enhances the performance of MOF-derived Sb-based negatrodes for advanced SIBs and LIBs compared to other post-synthetic modification methods such as high-temperature carbonization. These results challenge the prevailing preference for high-temperature carbonization-assisted structural modification of MOFs and can be extrapolated onto other viable MOF candidates as well.