Controllable 3D nanoporous Cu current collector towards enhanced Na storage for Sb electrode

Abstract

Utilizing 3D porous current collectors has been proved to be an efficient method to enhance the Na storage performance of alloying-type electrodes, however construction of suitable 3D porous structure is still a challenge. Here, a nanoporous Cu (NPCu) with controllable pore size is constructed by a simple and easily scalable strategy involving chemical oxidizing and chemical etching in sequence and utilized as the current collector to achieve nanoporous Sb (NPCu@Sb). This electrode configuration can afford enough free space for maintaining the electrode integrity and good electrical contact between active materials and current collector through accommodating volume variation, and thus avoids the electrochemical polarization increase. Simultaneously, the abundant nanopores can afford rapid transport channels for Na+. Thus, the NPCu@Sb shows obvious enhancement in the long-term cyclability and significant enhancement in the high-rate capacity. It displays a high reversible capacity of 602.4 mAh/g after 300 cycles with a high retention of 93.9 % at 0.3 A/g, and a high capacity of 502.8 mAh/g even at high current density of 10 A/g, better than most of previous reports. This work provides a new pathway to enhance the Na storage performance through constructing nanoporous current collector using a facile strategy.