Heterojunction of SnO2/Sn nanoparticles coated by graphene-like porous carbon as ultrahigh capacity anode of lithium-ion batteries

SnO 2 -based anode of lithium-ion batteries (LIB) suffers from excessive volume expansion and low conductivity, resulting in very poor capacity stability and rate capability. To solve the problems, three kinds of SnO 2 /Sn@carbon heterostructures were synthesized by a salt template following calcination using tartaric acid, p-phthalic acid and ethylenediamine tetraacetic acid with different carboxyl groups as carbon sources, respectively. The acidity, carbon atoms number and position affect the ratio of SnO 2 /Sn, the morphology and content of derived carbon, the advantage crystal plane and the surface defects of SnO 2 . The carbon atoms located at carboxyl are transformed to CO and formed pores, and the carbon atoms at alkane chain are polycondensed and transformed to amorphous carbon during annealing process. The SnO 2 /Sn@C derived from tartaric acid (SnO 2 /Sn@TA) has the largest ratio of SnO 2 /Sn, which fixed on graphene-like porous carbon , exposed the most surface defects and more high energy crystal plane. The specific structure ensures structural stability and ultrahigh capacity, lower Li + diffusion barrier energy and super rate capability. It exhibits the charge/discharge capacity of 1059.7/1064.4 mAh g −1 at 2 A g −1 after 1500 cycles and super rate performance of 399.3/404.5 mAh g −1 at 6 A g −1 , which are superior to most reference data.