SnO2 nanoparticles embedded in 3D nanoporous/solid copper current collectors for high-performance reversible lithium storage†
Nanostructured SnO2 is an attractive anode material for high-energy-density lithium-ion batteries because of the fourfold higher theoretical charge capacity than commercially used graphite. However, the poor capacity retention at high rates and long-term cycling have intrinsically limited applications of nanostructured SnO2 anodes due to large polarization and ∼300% volume change upon lithium insertion/extraction. Here we report the design of a SnO2-based anode, which is constructed by embedding SnO2 nanoparticles into a seamlessly integrated 3D nanoporous/solid copper current collector (S/NP Cu/SnO2), with an aim at tackling both problems for the high-performance reversible lithium storage. As a result of the unique hybrid architecture that enhances electron transfer and rapid access of the lithium ion into the particle bulk, the S/NP Cu/SnO2 anode can store charge with a capacity density as high as ∼3695 mA h cm−3 and an exceptional rate capability. Even when the discharge rate is increased by a factor of 160 (12 A g−1), it still retains ∼1178 mA h cm−3, one order of magnitude higher than that of a traditional SnO2-based electrode (∼111.6 mA h cm−3), which is assembled by mixing SnO2 nanoparticles with conductive carbon black and a polymeric binder and coating on flat Cu foil. In addition, not only do the rigid Cu skeleton and the stable Cu/SnO2 interface improve the microstructural stability, but also the pore channels accommodate the large SnO2 volume changes, enlisting the S/NP Cu/SnO2 anode to exhibit high specific capacity over 1000 cycles at a high rate.