Heteroatom facilitated preparation of electrodes for sodium ion batteries

Sodium ion batteries are attractive due to the abundance of sodium in the earth's crust. Sodium ion is larger than the lithium ion; hence, transforming the understanding emanated from lithium ion battery research into sodium ion battery investigations is not straightforward. However, a successful lithium battery electrode exhibited impressive performance while it was being used as an electrode in a sodium ion battery. This was an exception. Oen, natural resources are carbonized to prepare sodium ion battery electrodes. These electrodes exhibit specic capacities ranging between 180 mA h g 1 to 355 mA h g . Conjugated and vinyl polymers can be carbonized to prepare sodium ion battery electrodes. One common feature of these electrodes is heteroatom doping. Sulfur and nitrogen atoms increase the spacing between the graphene layers, which improves sodium ion insertion and deinsertion. Recently, conjugated porous polymers (CPPs) have become a preferred precursor for the synthesis of energy storage materials. We hypothesized that a CPP comprising of sulfur, nitrogen and oxygen would be a useful precursor for preparing carbon-based electrodes with increased interlayer spacings. The removal of oxygen during carbonization was easier than the removal of other heteroatoms during high temperature annealing. However, the removal of heteroatoms varies as a function of temperature. Thus, at the optimum temperature, the interlayer spacing, as well as the presence of heteroatoms, can become ideal for synthesis of a sodium ion battery electrode. To test this hypothesis, we synthesized a CPP (Scheme 1) using Stille coupling. Then, the CPP was carbonized at three temperatures (800, 1000 and 1200 C) to identify suitable synthesis conditions for a sodium ion battery electrode. One of the carbonized materials showed an impressive specic