Dual-metal synergy in MOFs: A green synthesis high-yield strategy for anodes with all-climate high-performance lithium storage

The introduction of secondary metal ions into monometallic metal–organic frameworks (MOFs) has emerged as an effective strategy for enhancing energy storage properties compared to their monometallic counterparts. Bimetallic MOFs exhibit superior performance due to their increased active site density, optimized local crystallinity, and reduced long-range disorder. Using a facile room-temperature stirring method, we successfully synthesized Ni/Co bimetallic MOFs, with the Ni/Co-MOF (NC-7) material achieving an exceptional synthesis yield of 98.7%. Electrochemical characterization demonstrates that NC-7 delivers a reversible specific discharge capacity of 1063.2/1077.4 mAh·g⁻¹ at 0.1 A·g⁻¹, surpassing those of the corresponding Co- and Ni-based monometallic MOFs. Remarkably, the NC-7 electrode maintains outstanding cycling stability, retaining 70.42% of its capacity after 60 cycles at −30 °C and exhibiting a 37.1% enhancement at 60 °C. When assembled into full cells with LiFePO₄ cathodes, the material retains a specific capacity of 191.0 mAh·g⁻¹ after 100 cycles at 0.1 A·g⁻¹. To further elucidate the lithium storage mechanism, we conducted in-situ Fourier-transform infrared (FTIR) spectroscopy to dynamically characterize the first-cycle charge–discharge process. The in-situ FTIR analysis revealed reversible C=C/COO⁻ vibrational changes (1250–1310 cm⁻¹) during lithiation/delithiation, confirming synergistic lithium storage via carboxylate-benzene conjugation in NC-7. These findings not only validate the potential of bimetallic MOFs in energy storage applications but also establish foundational guidelines for rational material design and performance optimization.