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The design of a wrap‐type AFSC is very similar to that of a parallel‐type fiber AFSC, which encapsulates two electrodes into a protective flexible tube instead of placing them on a flexible substrate [53, 59, 62,110–112]. Recently, Lu and his co‐workers [112] successfully synthesized N and low valence‐state Mo dual‐doped MoO₃ nanowires on carbon fibers, which was coupled with MnO₂@TiN‐loaded carbon fiber cathode and sealed with heat‐shrinkable tube to fabricate a wrap type solid‐state ASC (denoted as MnO₂@TiN//N‐MoO_3‐x) (Figure 1.8a). The galvanostatic charge/discharge (GCD) curves of MnO₂@TiN//N‐MoO_3‐x with different current densities in Figure 1.8b indicate that the stable operating voltage of the device reaches a significantly high value of 2.0 V. The ASC device also shows superior rate capability when current density increased by 15 folds (Figure 1.8c). More importantly, the excellent flexibility and mechanic robustness enabled the fiber AFSC device to perfectly maintain its electrochemical performances in bent and even knotted conditions (Figure 1.8d). Benefiting from the ultrahigh output voltage and Faradaic electrodes with improved conductivity, the MnO₂@TiN//N‐MoO_3‐x device exhibited a maximum energy and power density of 2.29 mW h cm⁻³ and 1.64 W cm⁻³ respectively, outperforming many other fiber‐shaped SC devices reported (Figure 1.8e).

Figure 1.8 (a) Schematic illustration of the as‐assembled fiber‐shaped MnO₂@TiN//N‐MoO_3‐x‐ASC device. (b) GCD curves of our fiber‐shaped AFSC device. (c) Linear capacitances and volumetric capacitances of the fiber‐shaped AFSC device as a function of current density. (d) CV curves collected at 100 mV s⁻¹ for the fiber‐shaped AFSC device under different conditions (left) and corresponding device pictures (right). (e) Ragone plots for the fiber‐shaped AFSC device and other recently reported fiber‐shaped FSCs.

Source: Reproduced with permission [112]. © 2016, Wiley‐VCH.