Fig. 1

CITIC construction new energy team releases latest European PV market forecast[1]"

Fig. 2

2011—2021 Chinese new energy vehicle sales and growth rate"

Fig. 3

Price and growth rate of battery-grade lithium carbonate (2020.02—2022.03)"

Fig. 4

Distribution of global proven lithium resources and reserves in 2020"

Fig. 5

Distribution of global sodium resource production in 2020"

Table 1

Lithium-ion battery vs. sodium-ion battery"

Fig. 6

Working principle of sodium ion battery[14]"

Table 2

Comparison of cathode materials for sodium ion batteries"

Fig. 7

Schematic diagram of the crystal structure of orthorhombic crystalline Na0.44MnO2[22]"

Fig. 8

Cycle performance curve of Na4Mn9O18 aqueous full cell at 4 C[23]"

Fig. 9

Structural electron microscopy (SEM) image of Na0.44MnO2 microrods[24]"

Fig. 10

Structure electron microscope (SEM) image of Na0.44MnO2 nanowire[25]"

Fig. 11

Schematic diagram of the crystal structure of O2, O3, P2 and P3 type transition metal oxides[26]"

Fig. 12

Charge/discharge curve of NaMnO2 material at 0.1 C current density[27]"

Fig. 13

Electron microscope (SEM) image of the macroscopic structure of Na0.67Ni0.2Fe0.15Mn0.65O2 cathode material[30]"

Fig. 14

(a) Schematic diagram of the fabricated Na0.7MnO2.05 hollow microsphere structure and Na0.7MnO2.05@PPy polypyrrole (PPy) covered hollow microsphere structure; (b) SEM image of the MnO2 hollow microsphere structure; (c) SEM image of the Na0.7MnO2.05 hollow microsphere structure; (d) Na0.7MnO2.05@PPy polypyrrole (PPy)-covered hollow microsphere structure SEM image[31]"

Fig. 15

(a) Preparation process of Na0.91MnO2 porous microcube structure and Na0.91MnO2@PPy polypyrrole-coated porous microcube structure, (b) SEM images of MnCO3 porous microcube, (c) Na0.91MnO2 porous microcube structure, (d, e) Na0.91MnO2@PPy polypyrrole-coated porous micro cube structure SEM images, (f—i) elemental mapping images of Na, O, Mn and N in Na0.91MnO2@PPy[32]"

Fig. 16

Flow diagram of P2-type Na0.67Ni0.15Mn0.85O2 fullerene-like hollow polyhedra formed by a two-step self-deposition strategy[33]"

Fig. 17

Schematic diagram of the laminar structure of Na2Mn3O7 (a) in the c-axis direction and (b) in the (-5, 5, 0) direction[34]"

Fig. 18

Na0.44MnO1.93F0.07 a layer-tunnel hybrid structure electron microscopy (SEM) image[35]"

Fig. 19

Cycling performance and coulombic efficiency of Na0.46Mn0.93Al0.07O1.79F0.21 with undoped sodium manganate material at 5 C rate[36]"

Table 3

Preparation method and electrochemical properties of Na x MnO2(x ≤0.5) and element-doped cathode materials"

Table 4

Preparation method and electrochemical properties of Na x MnO2(x>0.5) cathode materials"

Fig. 20

Charge/discharge curve of Na2/3Ni1/3Mn2/3O2 at 2—4 V, 0.05 C[40]"

Fig. 21

Electrochemical characteristics of Na2/3[Mg0.28Mn0.72]O2 in Na ion batteries (a) Na/Na2/3[Mg0.28Mn0.72]O2 cell cyclic charge and discharge curves at a rate of 10 mAh/g in the voltage range of 1.5—4.4 V; (b) Discharge capacity and coulombic efficiency of the cells[43]"

Fig. 22

(a) Charging and discharging curves at 0.1 C rate; (b) Charging and discharging curves for the first cycle at 0.1 C, 1 C, 3 C, 10 C, and 30 C rates; (c) Charging and discharging curves at 1 C rate; (d) Charging and discharging cycle performance and efficiency at 1 C rate; (e) Charging and discharging cycle performance at 10 C, 20 C, and 30 C rates and efficiency at 10 C[45]"

Table 5

Preparation method and electrochemical properties of Na x (Mn y M1 j )O2 (x>0.5) cathode materials"

Fig. 23

(a) Charge and discharge curves of the battery; (b) cycle efficiency of the battery[62]"

Table 6

Preparation method and electrochemical properties of Na x (Mn y M2 j )O2 (x>0.5) cathode materials"

Fig. 24

Schematic diagram of the structure of the P2-type NCM nano-plate and the multiplicative properties of the nano-plate NCM with non-nano-plate NCM-P particle precursors[89]"

Table 7

Preparation method and electrochemical properties of Na x (Mn y Mmj )O2 (x>0.5) cathode materials"

Fig. 25

(a) Schematic representation of the material structure design idea. And illustrated the Li/Ni blend as a representative of the nickel-rich cathode and the Na+ vacancies inherent in the P2 structure. XRD plots of the prepared (b) Na2/3Ni1/3Mn2/3O2 and (c) Na2/3Li1/9[Ni2/9Li1/9Mn2/3]O2 materials[100]"

Table 8

Preparation method and electrochemical properties of (Na x A i )(Mn y M j )O2 (x>0.5) cathode materials"

Table 9

Preparation method and electrochemical properties of Na x (Mn y M j ) (O2-k nM k ) (x>0.5) cathode materials"

Fig. 26

Process diagram of material preparation and influence of material properties[76]"

Fig. 27

Cycling performance of the original sample and samples coated with different molar concentrations of ZnO (1%, 3%, 5% and 7%) at a current density of 0.5 C; (b) rate performance of the original sample and samples coated with ZnO (1%, 3%, 5% and 7%) at different current densities (0.1, 0.2, 0.5, 1, 2 C)[47]"

Fig. 28

Cycling performance and corresponding Coulomb efficiency of the pristine and clad cathodes at different rates at 1.8—4.0 V (a) 5 C; (b) 10 C[55]"

Fig. 29

Multiplicative cycle diagram and efficiency diagram of In2O3 coated Na0.44MnO2 versus uncoated material[109]"