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Graphitic porous carbons with combined two-dimensional layer crystallinity and porosity have shown great potential for energy storage. This report documents the design of ternary carbide (MAX)-derived carbon (MDC) from a MAX precursor with highly porous graphitic features, prepared through one-pot chlorination synthesis. The MDCs exhibited a peculiar discharge capacity pattern during long-term cycling, in which the discharge capacity decreased from 620 mA h g−1 (1st cycle) to 500 mA h g−1 (20th cycle) and then increased in proportion to the cycle number, reaching a value of ∼680 mA h g−1 (300th cycle) at 0.1C-rate. Even at high 0.5C-rate, the discharge cycling pattern was similar to that at 0.1C-rate, with a high reversible capacity of ∼650 mA h g−1 at the 500th cycle. Furthermore, despite applying two C-rate steps from 0.1C to 0.5C, an outstanding performance of ∼720 mA h g−1 at 0.1C-rate was observed at the 400th cycle, eclipsing the cycleability at a single 0.1 C-rate. In the MDCs, the order-to-disorder transformation in parts of the graphite upon prolonged cycling gave rise to defect structures consisting of many connected pores, which can facilitate Li-ion migration and increase the ion paths and storage sites. |
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