Sn accommodation in tunable-void and porous graphene bumper for high-performance Li- and Na-ion storage

Nanoscale microstructure designing is playing an important role in improving the performance of electrode materials of an electrochemical battery. The Sn based anode is among the very high-capacity but less-stable materials, and has been used mostly for anode of the Li-ion battery with unsatisfactory performance. In this work, we design a new type of 3D porous graphene and nano-Sn composite (Sn/Void@G) by simple one-step annealing of graphene oxide, polystyrene spheres and stannic chloride for both high performance Li- and Na-ion battery anodes. More importantly, the 3D porous graphene formed tunable micro-nano void as a highly efficient “bumper” to accommodate the large volume expansion of nano-Sn particles. As results, the discharge specific capacity of the Sn/Void@G, anode still remains 45.3% while the charge-discharge current is increased 50 times, and the capacity is more than 400 mAh g⁻¹ after 500 cycles at 5C rate. For Na storage, the integrated anodes deliver the Na storage capacity of 786.1 mAh/g at 0.1C rate and the capacity of more than 340 mAh/g after 800 cycles at 2C rate. The present result on Li and Na ion battery may pave the way to next generation high power and energy density batteries.