Table 1

Comparison of relative atomic mass, ion radius, standard potential, theoretical capacity, and crustal abundance of metals used in common secondary batteries."

Fig 1

Application classification of MXene in AZIBs."

Fig 2

(a) Schematic illustration of the synthesis of MnOx@Ti3C2Tx; (b) SEM image of MnOx@Ti3C2Tx; (c) schematic illustration of the parallel circuitry at nanoscale based on MnOx@Ti3C2Tx; (d) rate performance of MnOx@Ti3C2Tx 54. (e) SEM image of 3D Ti3C2Tx@MnO2 microflowers; (f) long-term cycling stability (current density of 500 mA∙g−1) evaluated using the coulombic efficiency of 3D Ti3C2Tx@MnO2 microflowers in AZIBs 55."

Fig 3

(a) Optical images of V2O5/MXene electrode in 3 mol∙L−1 Zn(CF3SO3)2 aqueous solution under different soaking times; (b) differential charge state density of V2O5-MXene heterointerface; (c) contour plot of in situ XRD characterization with corresponding voltage profile 59."

Fig 4

(a) Optical images and (b) cycle stability at 5 A∙g−1 of the VO2/MXene films 60; (c) schematic of S-Ti3C2Tx/PANI preparation and rate performance of all cathodes 61."

Fig 5

(a) CV curves of Ti3C2 (OF) and Ti3C2Cl2 at a scan rate of 1 mV∙s−1; (b) typical GCD curves of Ti3C2 MXenes with different terminals at the current density of 0.5 A∙g−1; (c) CV curves of Ti3C2Br2 and Ti3C2I2 at a scan rate of 1 mV∙s−1, (d) rate capability and long-term cycling performance of Ti3C2Br2 and Ti3C2I2 62."

Fig 6

(a) Rate capability of V2CTx MXene 63; (b) SEM images of V2CTx prepared by HF etching method; (c) long-term cycling performance of V2CTx-based ZHIB at 10 A∙g−1; (d) schematic illustration of the possible mechanism of the structural and phase transition of the V2CTx cathode 64."

Fig 7

(a) Schematic illustration, morphology and structure evolution of V2CTx cathodes with different activation voltages; (b) cycling performance of 1.8-V2CTx at 30 A∙g−1 66."

Fig 8

(a) Diagrams of synthesis and structure analysis of K-V2C@MnO2; (b) long-term cycling performance of K-V2C@MnO2 at quite high current densities 70."

Fig 9

CV curves of Nb2CTx recorded at 5 mV∙s−1 up to 2.0 V (a) and 2.4 V (c); GCD curves of Nb2CTx recorded at 1 A∙g−1 up to 2.0 V (b) and 2.4 V (d); calculated proportions of plateau region in specific energy and capacity at 1 A∙g−1 (e); SEM images with EDS mapping data at 2.4 V discharge/charge states (f) 73."

Table 2

Summary of MXene for zinc anodes protection."

Fig 10

(a) The schematic diagram of fabricating flexible layered Ti3C2Tx@Zn paper; (b) corresponding plating/stripping profiles of the 5th, 10th, 20th, and 50th cycle of (b) bare Zn anode and (c) Ti3C2Tx@Zn anode; (d) voltage profiles of Zn plating/stripping process with bare Zn anode (black) and Ti3C2Tx@Zn anode (red) at a current density of 1 mA∙cm−2 and an area capacity of 1 mAh∙cm−2 81."

Fig 11

(a) Illustration of synchronously reducing and assembling MXene layer on the surface of Zn foil, illustration of Zn plating behavior of (b) MXene-coated Zn, and (c) pure Zn; (d) long-term cycling performance of symmetric cells with pure Zn and MXene-coated Zn at 0.2 mA∙cm−2 87; (e) schematic illustration of the Zn deposition process on the MXene matrix concerning initial Zn tiling and subsequent coherent heterogeneous interface construction; (f) long-term cyclic performance of symmetric batteries at 2 mA∙cm−2 with a fixed capacity of 1 mAh∙cm−2; (g) comparison for long-term cyclability of Zn//Ti3C2I2 and MCl-Zn//Ti3C2I2 batteries at 3 A∙g−1 88."