▎ 摘　　要

The electrochemical performances of most transition metal oxides for lithium and sodium ion batteries are often greatly hindered by rapid capacity decay caused by their low intrinsic electrical conductivity and sluggish kinetics during cycling. In this work, we develop a novel coral-like composite consisting of Mn3O4 nanotubes embedded in 2D porous graphene sheets (denoted as Mn3O4@pGS) by using dual templates NaCl crystals and SiO2 nanospheres. Benefitting from the special construction, the Mn3O4@pGS composite exhibits unprecedented electrochemical properties. The as-prepared Mn3O4@pGS composite represents a high specific capacity of 770 mAh g(-1) after 200 cycles when evaluated as an anode for lithium storage. More importantly, the Mn3O4@pGS electrode exhibits a charge capacity of 233 mAh g(-1) after 55 cycles for sodium storage. The enhanced high-rate lithium/sodium storage capacity and stability originate from the strong synergistic effects between high loading content of Mn3O4 and good electron conductivity of 2D porous graphene sheets, which can not only provide enough void space for accommodation of the mechanical stresses induced by the volume variations, but also effectively avoid the aggregation of Mn3O4 nanotubes during the repeated discharge/charge processes. The synthesis strategy proposed here introduces a new methodology to fabricate transition metal oxide@porous graphene sheet composites for energy storage and conversion.