Sodium-ion battery, positive electrode plate for sodium-ion battery, positive active material, battery module, battery pack, and device
This application relates to a sodium-ion battery, a positive electrode plate for a sodium-ion battery, a battery module, a battery pack, and a device. The sodium-ion battery according to this application includes a positive electrode plate, a negative electrode plate, a separator, and an electrolytic solution. The positive electrode plate includes a positive active material. A molecular formula of the positive active material satisfies Na a Li b M 0.7 Fe 0.3−b O 2±δ , M is a transition metal ion, 0.67<a<1.1, 0<b<0.3, 0≤δ≤0.1, and a ratio of R ct to R f of the positive active material satisfies 1.0<R ct /R f <20.0. R ct is a charge transfer resistance of the positive active material measured in a button battery based on alternating current impedance spectroscopy, and R f is a diffusion resistance of the positive active material measured in the button battery based on the alternating current impedance spectroscopy.
1 . A sodium-ion battery, comprising a positive electrode plate, a negative electrode plate, a separator, and an electrolytic solution, wherein
the positive electrode plate comprises a positive active material, a molecular formula of the positive active material satisfies Na a Li b M 0.7 Fe 0.3−b O 2±δ , M is a combination of Mn and one of Cu, Zn, and Mg, 0.67<a<1.1, 0.05<b<0.2, 0<δ<0.1, and in a charge and discharge curve of a button battery made of the positive active material, a ratio of R ct to R f of the positive active material satisfies 2<R ct /R f <3 for the first cycle and 4.29≤R ct /R f ≤6.72 for the 100 th cycle;
R ct is a charge transfer resistance of the positive active material measured in the button battery based on alternating current impedance spectroscopy; and
R f is a diffusion resistance of the positive active material measured in the button battery based on the alternating current impedance spectroscopy,
a median diameter D v 50 of the positive active material (μm), a specific surface area S (m 2 /g) of the positive active material, and the R ct /R f satisfy:
47.5
<
R
ct
/
R
f
*
D
v
5
0
S
<
160.
2 . The sodium-ion battery according to claim 1 , wherein a resistance of the positive electrode plate is R≤1,000 mΩ.
3 . The sodium-ion battery according to claim 1 , wherein a resistance of the positive electrode plate is R≤100 mΩ.
4 . The sodium-ion battery according to claim 1 , wherein a tapped density of the positive active material is greater than 1 g/cm 3 .
5 . The sodium-ion battery according to claim 1 , wherein a tapped density of the positive active material is within a range of 1.5˜3 g/cm 3 .
6 . The sodium-ion battery according to claim 1 , wherein a compacted density of the positive active material under 8 tons is within a range of 1.5˜4.5 g/cm 3 .
7 . The sodium-ion battery according to claim 1 , wherein a median diameter D v 50 of the positive active material is within a range of 0.05˜50 μm.
8 . The sodium-ion battery according to claim 1 , wherein a median diameter D v 50 of the positive active material is within a range of 3˜30 μm.
9 . The sodium-ion battery according to claim 1 , wherein a specific surface area S of the positive active material is within a range of 0.01˜30 m 2 /g.
10 . The sodium-ion battery according to claim 1 , wherein a specific surface area S of the positive active material is within a range of 0.1˜10 m 2 /g.
11 . The sodium-ion battery according to claim 1 , wherein the negative active material in the negative electrode plate is a carbon material.
12 . The sodium-ion battery according to claim 1 , wherein the negative active material in the negative electrode plate is a hard carbon material.
13 . The sodium-ion battery according to claim 1 , wherein an areal density A (g/m 2 ) of a single-sided positive active material layer of the positive electrode plate and an areal density B (g/m 2 ) of a single-sided negative active material layer of the negative electrode plate satisfy: 1.8<A/B<2.57.
14 . A device that uses a sodium-ion battery as a power supply, wherein the device comprises the sodium-ion battery according to claim 1 .
15 . A positive active material for a sodium-ion battery, wherein
a molecular formula of the positive active material satisfies Na a Li b M 0.7 Fe 0.3−b O 2±δ , M is a combination of Mn and one of Cu, Zn, and Mg, 0.67<a<1.1, 0.05<b<0.2, and 0≤δ≤0.1, and
in a charge and discharge curve of a button battery made of the positive active material, a ratio of R ct to R f of the positive active material satisfies 2<R ct /R f <3 for the first cycle and 4.29≤R ct /R f ≤6.72 for the 100 th cycle,
wherein,
R ct is a charge transfer resistance of the positive active material measured in the button battery based on alternating current impedance spectroscopy; and
R f is a diffusion resistance of the positive active material measured in the button battery based on the alternating current impedance spectroscopy,
a median diameter D v 50 of the positive active material (μm), a specific surface area S (m 2 /g) of the positive active material, and the R ct /R f satisfy:
47.5
<
R
ct
/
R
f
*
D
v
5
0
S
<
160.