Hollow porous NiCo2O4-nanoboxes (NCO-NBs) were synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the template followed by a subsequent annealing treatment. The structure and morphology of the NCO-NBs were characterized using X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. When tested as potential anode materials for lithium-ion batteries, these porous NCO-NBs with a well-defined hollow structure manifested enhanced performance of Li storage. The discharge capacity of the NCO-NBs remained 1080 mA h g−1 after 150 cycles at a current rate of 500 mA g−1 and 884 mA h g−1 could be obtained at a current density of 2000 mA g−1 after 200 cycles. Even when cycled at a high density of 8000 mA g−1, a comparable capacity of 630 mA h g−1 could be achieved. Meanwhile, the Na storage behavior of NCO-NBs as anode materials of sodium ion batteries (SIBs) was initially investigated and they exhibited a high initial discharge capacity of 826 mA h g−1, and a moderate capacity retention of 328 mA h g−1 was retained after 30 cycles. The improved electrochemical performance for NCO-NBs could be attributed to the hierarchical hollow structure and the desirable composition, which provide enough space to alleviate volume expansion during the Li+/Na+ insertion/extraction process and facilitate rapid transport of ions and electrons.

Novel 3-dimensional (3 D) flower-like NiCo2O4 (NCO) nanorod clusters are fabricated by a facile hydrothermal process using styrene–acrylonitrile copolymer (PSA) nanospheres as a complex agent. The structure and morphology of NCO are characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the PSA modified NCO (PNCO) exhibits excellent electrochemical performance. Compared with pure NCO, the flower-like PNCO materials with enough free space as anodes in lithium ion batteries (LIBs) deliver an initial discharge capacity of 1519.1, 1447.3 and 1337.3 mA h g−1 at the current densities of 500, 1000 and 2000 mA g−1, as well as 1417.5, 819.0 and 719.5 mA h g−1 after 100 cycles. Meanwhile, they display improved rate performance at elevated current rates, such as 1247.3, 1193.5 and 944.5 mA h g−1 at current densities of 1000, 2000 and 4000 mA g−1, respectively. They have great prospects for the application of anode materials for lithium-ion batteries.

Amorphous and crystalline hybrid structure Co2SnO4/C composites have been prepared by a facile way using coprecipitation process and high-energy ball milling technology. Electrochemical performance tests show that the composite anodes could maintain reversible capacity of higher than 550 mAh g−1 up to 100 cycles, much better than that of pure Co2SnO4 (194.1 mAh g−1). These materials also present better rate performance with fairly stable capacity retention when the current ranges from 100 to 500 mA g−1. Impedance measurements confirm that these composites are more beneficial for lithium diffusion compared to pure Co2SnO4. The graphite carbon not only buffers the volume expansion-related cracking but also provides excellent conductivity for this material.

Hollow porous NiCo2O4-nanoboxes (NCO-NBs) were synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the template followed by a subsequent annealing treatment. The structure and morphology of the NCO-NBs were characterized using X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. When tested as potential anode materials for lithium-ion batteries, these porous NCO-NBs with a well-defined hollow structure manifested enhanced performance of Li storage. The discharge capacity of the NCO-NBs remained 1080 mA h g−1 after 150 cycles at a current rate of 500 mA g−1 and 884 mA h g−1 could be obtained at a current density of 2000 mA g−1 after 200 cycles. Even when cycled at a high density of 8000 mA g−1, a comparable capacity of 630 mA h g−1 could be achieved. Meanwhile, the Na storage behavior of NCO-NBs as anode materials of sodium ion batteries (SIBs) was initially investigated and they exhibited a high initial discharge capacity of 826 mA h g−1, and a moderate capacity retention of 328 mA h g−1 was retained after 30 cycles. The improved electrochemical performance for NCO-NBs could be attributed to the hierarchical hollow structure and the desirable composition, which provide enough space to alleviate volume expansion during the Li+/Na+ insertion/extraction process and facilitate rapid transport of ions and electrons.