Synthesis, structure, and lithium storage performance of non-conductive metal-organic frameworks for high-performance lithium-ion batteries

Some metal-organic frameworks (MOFs) cannot be used as electrode materials for lithium-ion batteries because of their inferior intrinsic electrocatalytic activity and poor conductivity. Herein, the application of two nickel (II) cluster-based pillar-layered MOFs, Ni-mba-Na ([Ni8(mba)6(Cl)2Na(OH-)3]n, H2mba is 2-mercaptobenzoic acid) and Ni-mba-K ([Ni8(mba)6(Cl)2K(OH-)3]n), as electrode materials are reported. They differ from conductive MOFs because they are insulators with small specific surface areas (<10 m2g-1) and H2mba is an inexpensive chemical raw material. The conductivities of Ni-mba-Na and Ni-mba-K at 30 celcius are 4.002 x 10-10 and >10-11 S cm-1, respectively. They exhibit excellent lithium storage performance, stability, and high inherent density (1.835 and 1.838 g cm-3) and specific capacity (1091.6, and 905.6 mAh/g at the first cycle). Design recommendations for these MOFs are provided based on their structure and performance differences. This paper provides a novel application of non-conductive MOFs in the energy storage field and strategy for design of high-performance electrode materials for lithium-ion batteries.