Low temperature synthesis of polyhedral hollow porous carbon with high rate capability and long-term cycling stability as Li-ion and Na-ion battery anode material

Abstract

A unique polyhedral-shaped hollow porous carbon with high specific capacity, high rate capability, and excellent cycling stability as both lithium-ion and sodium-ion battery anode material has been prepared from a Ni-ion exchanged resin at significantly low temperature (500 °C). Low temperature synthesis is achieved by room temperature exposure of Ni-ion exchanged resin to hydrazine hydrate, which reduces Ni2+ to active Ni metal catalyst prior to calcination. As an anode material for lithium-ion and sodium-ion batteries, the material delivers large reversible capacity and long-term cycle stability even at high current densities. As a lithium-ion battery anode material, it delivers 620 and 225 mAh g−1 at 1 and 20 A g−1, respectively, and 380 mAh g−1 after 3000 cycles at 5 A g−1. As a sodium-ion battery anode material, it delivers 227 and 133 mAh g−1 at 1 and 20 A g−1, respectively, and 144 mAh g−1 after 9000 cycles at 5 A g−1. The high rate capability and cycling stability arises from an appropriate balance of graphitization, nanoporosity, and thin-walled interconnected hollow structure. Overall, the performance of the material is exceptional for porous carbon, especially considering its low temperature bulk synthesis method.