Pre-Oxidation-Tuned Microstructures of Carbon Anodes Derived from Pitch for Enhancing Na Storage Performance

Disordered carbons have captured extensive interest as anode materials for Na-ion batteries (NIBs) due to the abundant resources, competitive specific capacity, and low cost. Here, a facile strategy of pre-oxidation is successfully adopted to tune the microstructure of carbon anode to facilitate sodium storage. Pitch is selected as the low-cost and high carbon yield precursor. An easy pre-oxidation treatment in air can enable pitch to realize an effective structural conversion from ordered to disordered at further carbonization processes. Compared with the carbonized pristine pitch, the carbonized pre-oxidation pitch increases the carbon yield from 54 to 67%, the sodium storage capacity from 94.0 to 300.6 mAh g(-1), and the initial Coulombic efficiency from 64.2 to 88.6%. Experiment results reveal that the introduction of oxygen based functional groups is the key to achieve the highly disordered structure, not only ensuring the cross-linkage during low-temperature pre-oxidation process but also suppressing the carbon structure from melting and rearranging in the high-temperature carbonization process. Most importantly, this facile pre-oxidation strategy can also be extended to other carbon precursors to facilitate the low-cost and high-performance disordered carbon anodes for NIBs and beyond.