Industry‐Scale and Environmentally Stable Ti₃C₂T_x MXene Based Film for Flexible Energy Storage Devices

Abstract

MXenes, 2D transition metal carbides, and nitrides have attracted tremendous interest because of their metallic conductivity, solution processability, and excellent merits in energy storage and other applications. However, the pristine MXene films often suffer from poor ambient stability and mechanical properties that stem from their polar terminal groups and weak interlayer interactions. Here, a heteroatom doping strategy is developed to tailor the surface functionalities of MXene, followed by the addition of large-sized reduced graphene oxide (rGO) as conductive additives to achieve a scalable production of S, N-MXene/rGO (SNMG-40) hybrid film with high mechanical strength (≈45 MPa) and energy storage properties (698.5 F cm −3 ). Notably, the SNMG-40 film also demonstrates long-term cycling stability (≈98% capacitance retention after 30 000 cycles), which can be maintained under ambient condition or immersed in H 2 SO 4 electrolyte for more than 100 days. The asymmetric supercapacitor (aMGSC) based on SNMG-40 film shows an ultrahigh energy density of 22.3 Wh kg −1 , which is much higher than those previously reported MXene-based materials. Moreover, the aMGSC also provides excellent mechanical durability under different deformation conditions. Thus, this strategy makes MXene materials more competitive for real-world applications such as flexible electronics and electromagnetic interference shielding.

Dandelion‐like Nanospheres Synthesized by CoO@CuO Nanowire Arrays for High‐Performance Asymmetric Supercapacitors

“…For the electrode material, the b value can be calculated by formula i= av b to judge the properties of the electrode material in the process of charge and discharge. If the value of b is 0.5, the electrode material behaves as battery properties; if the value of b is in the range of 0.5–1, the electrode material behaves as battery properties and pseudocapacitance properties; if the value of b≥1, the electrode material behaves as pseudocapacitance attributes [31] . The relationship between peak current and scan rates of CoO@CuO/Ni with Co : Cu=1 : 1 electrode are plotted in Figure 4g.The value of b is 0.5, which proves that the electrode material is battery property.…”

“…If the value of b is 0.5, the electrode material behaves as battery properties; if the value of b is in the range of 0.5-1, the electrode material behaves as battery properties and pseudocapacitance properties; if the value of b � 1, the electrode material behaves as pseudocapacitance attributes. [31] The relationship between peak current and scan rates of CoO@CuO/Ni with Co : Cu = 1 : 1 electrode are plotted in Figure 4g.The value of b is 0.5, which proves that the electrode material is battery property. Figure 4h displays that the as-prepared CoO@CuO/Ni electrode with Co : Cu = 1 : 1 possesses superior specific capacitances of 856 F g À 1 (385 C g À 1 ) at 0.58 A g À 1 , which is better than the recently reported CuO-based electrode materials.…”

Gelation‐Assisted Assembly of Large‐Area, Highly Aligned, and Environmentally Stable MXene Films with an Excellent Trade‐Off between Mechanical and Electrical Properties

“…[14,33] As expected, with the increase of APP content, the conductivity of MAF decreases slightly due to the insulating nature of APP, which is also consistent with the trend commonly observed for hybrid films [23,44] but still remains at a high level. Moreover, combining the tensile strength and electrical performance, these values of MAF-0.25 are also superior to those of most MXene composite films recently developed (Figure 3g and Table S2, Supporting Information), [14,16,23,25,27,28,31,35,38,44,[48][49][50][51][52][53] including CNF/MXene, [23,44] BC/MXene, [25,48] PDA/MXene, [16] ANF/MXene, [27,52] and rGO/MXene. [31,53] Even though the mechanical performance is numerically inferior to the stateof-the-art work, [14] MAF-0.25 shows excellent trade-off between conductivity and mechanical properties.…”

“…g) Comparison of the electrical conductivity and tensile strength between MAF-0.25 and previously reported MXene-based films. [14,16,23,25,27,28,31,35,38,44,[48][49][50][51][52][53] nearly comparable to that of PMF (9300.8 ± 401.5 S cm −1 ) and much higher than that of most reported MXene composite films. [19,21,23,47] The rolling process is also conducive to the increase of electrical conductivity (reach 11 580 ± 449.0 S cm −1 ) by suppressing the voids and gaps in the MXene film.…”

“…Alternatively, several other assembly techniques, such as blade coating, spin coating, and drop casting, have been exploited to produce large-area MXene films with improved quality. [17,[30][31][32] For instance, Zhang et al proposed a blade-coating method to fabricate large-scale MXene films composed of highly ordered flakes. [33] These MXene films demonstrate record tensile strength up to 570 MPa for a 940 nm thick film and electrical conductivity of 15 100 S cm −1 for a 214 nm thick film.…”