Nanoporous gyroid Ni/NiO/C nanocomposites from block copolymer templates with high capacity and stability for lithium storage†
A nanoporous Ni/NiO/C nanocomposite with a gyroid nanostructure was fabricated by using a nanoporous polymer with gyroid nanochannels as a template. The polymer template was obtained from the self-assembly of a degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by the hydrolysis of PLLA blocks. Templated electroless plating followed by calcination was performed to create a precisely controlled Ni/NiO gyroid nanostructure. After carbon coating, a well-interconnected nanoporous gyroid Ni/NiO/C nanocomposite can be successfully fabricated. Benefiting from the well-interconnected nanoporous structure with ultrafine transition metal oxide and uniform carbon coating, the gyroid nanoporous Ni/NiO/C nanocomposite electrodes exhibited high specific capacities at various rates (1240 mA h g−1 at 0.2 A g−1, 902 mA h g−1 at 2 A g−1 and 424 mA h g−1 at 10 A g−1) and excellent cyclability (809 mA h g−1 at 1 A g−1 after 1000 cycles, average coulombic efficiency 99.86%). This research demonstrates a universal approach for constructing a nanostructured electrode with explicitly controlled block copolymer phase separation.