Electrochemical apparatus and electronic apparatus including same
An electrochemical apparatus includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a first positive electrode material and a second positive electrode material. The first positive electrode material has good cycling stability and high initial coulombic efficiency, and the second positive electrode material has a high specific capacity and low initial coulombic efficiency during the first charge. This can compensate for the active lithium loss caused by the formation of SEI.
1. An electrochemical apparatus, comprising a positive electrode, a negative electrode, and an electrolyte; wherein
the positive electrode comprises a positive electrode current collector and a positive electrode material layer on at least one surface of the positive electrode current collector, and the positive electrode material layer comprises a first positive electrode material shown in Formula (I):
Li
1
+
x
Fe
y
Mn
z
M
1
-
y
-
z
PO
4
-
t
A
t
,
Formula
(
I
)
wherein
−0.1<x<0.1, 0<y≤1, 0≤z≤1, 0<y+z≤1, 0≤t<0.2, M comprises at least one of Ti, Zr, V, or Cr, and A comprises at least one of S, N, F, Cl, or Br; and
a second positive electrode material shown in Formula (II);
Li
1
+
r
Mn
1
-
p
X
p
O
2
-
s
T
s
,
Formula
(
II
)
wherein
−0.1<r<0.2, 0≤p<0.2, 0≤s<0.2, X comprises at least one of Fe, Co, Ni, Ti, Zn, Mg, Al, V, Cr, or Zr, and T comprises at least one of S, N, F, Cl, or Br; and
the positive electrode satisfies
0.5
≤
R
×
P
/
Q
≤
16
,
wherein
R is a numerical value representing a resistance of the positive electrode (in Ω); P is a numerical value representing a compacted density of the positive electrode (in g/cm 3 ); and Q is a numerical value representing a single-sided surface density of the positive electrode (in g/mm 2 ),
wherein Q is calculated according to Q=1540.25×m/Ar, where m is a numerical value representing a mass of the positive active material layer (in g), and Ar is a numerical value representing an area of the positive active material layer (in mm 2 ).
2. The electrochemical apparatus according to claim 1 , wherein 1.5≤R×P/Q≤10.
3. The electrochemical apparatus according to claim 1 , wherein R≤3.5.
4. The electrochemical apparatus according to claim 1 , wherein 1.6<P<2.6.
5. The electrochemical apparatus according to claim 1 , wherein 0.16<Q<0.45.
6. The electrochemical apparatus according to claim 1 , wherein a mass ratio of the first positive electrode material to the second positive electrode material is 5:1 to 99:1.
7. The electrochemical apparatus according to claim 1 , wherein based on a total mass of the positive electrode material layer, a percentage of the first positive electrode material is 80% to 98%.
8. The electrochemical apparatus according to claim 1 , wherein the second positive electrode material has a characteristic diffraction peak A in an X-ray diffraction pattern in a range of 15° to 16° and/or a characteristic diffraction peak B in a range of 18° to 19°, and a ratio of I A /I B of an intensity I A of the characteristic diffraction peak A to an intensity I B of the characteristic diffraction peak B satisfies 0<I A /I B ≤0.2.
9. The electrochemical apparatus according to claim 8 , wherein in the X-ray diffraction pattern of the second positive electrode material after a first cycle of charge, the characteristic diffraction peak A and the characteristic diffraction peak B both shift toward lower angles, with a shift magnitude less than 0.5°.
10. The electrochemical apparatus according to claim 1 , wherein the first positive electrode material comprises at least one of LifePO 4 , LiFe 0.5 Mn 0.5 PO 4 , Li 0.9 Fe 0.5 Mn 0.45 Ti 0.05 PO 4 , Li 0.9 Fe 0.5 Mn 0.45 Ti 0.04 Zr 0.01 PO 4 , or Li 0.95 FePO 3.95 F 0.05 ; and/or the second positive electrode material comprises at least one of LiMnO 2 , LiMn 0.9 Ni 0.1 O 2 , LiMn 0.9 Ni 0.05 Cr 0.05 O 2 , Li 0.95 MnO 1.95 F 0.05 , or Li 0.95 MnO 1.9 S 0.05 F 0.05 , (in g/cm 3 ); and Q is a numerical value representing a single-sided surface density of the positive electrode (in g/mm 2 ),
wherein Q is calculated according to Q=1540.25×m/Ar, where m is a numerical value representing a mass of the positive active material layer (in g), and Ar is a numerical value representing an area of the positive active material layer (in mm 2 ).
11. The electrochemical apparatus according to claim 1 , wherein the electrolyte comprises vinyl carbonate; wherein based on a total mass of the electrolyte, a percentage of the vinyl carbonate is 0.05% to 5%.
12. An electronic apparatus, comprising an electrochemical apparatus, the electrochemical apparatus comprises a positive electrode, a negative electrode, and an electrolyte, wherein
the positive electrode comprises a positive electrode current collector and a positive electrode material layer on at least one surface of the positive electrode current collector, and the positive electrode material layer comprises a first positive electrode material shown in Formula (I):
Li
1
+
x
Fe
y
Mn
z
M
1
-
y
-
z
PO
4
-
t
A
t
,
Formula
(
I
)
wherein
−0.1<x<0.1, 0<y≤1, 0≤z≤1, 0<y+z≤1, 0≤t<0.2, M comprises at least one of Ti, Zr, V, or Cr, and A comprises at least one of S, N, F, Cl, or Br; and
a second positive electrode material shown in Formula (II);
Li
1
+
r
Mn
1
-
p
X
p
O
2
-
s
T
s
,
Formula
(
II
)
wherein
−0.1<r<0.2, 0≤p<0.2, 0≤s<0.2, X comprises at least one of Fe, Co, Ni, Ti, Zn, Mg, Al, V, Cr, or Zr, and T comprises at least one of S, N, F, Cl, or Br; and
the positive electrode satisfies Formula (1):
0.5
≤
R
×
P
/
Q
≤
16
,
Formula
(
1
)
wherein
R is a numerical value representing a resistance of the positive electrode (in Ω); P is a numerical value representing a compacted density of the positive electrode (in g/cm 3 ); and Q is a numerical value representing a single-sided surface density of the positive electrode (in g/mm 2 ),
wherein Q is calculated according to Q=1540.25×m/Ar, where m is a numerical value representing a mass of the positive active material layer (in g), and Ar is a numerical value representing an area of the positive active material layer (in mm 2 ).
13. The electronic apparatus according to claim 12 , wherein 1.5≤R×P/Q≤10.
14. The electronic apparatus according to claim 12 , wherein R≤3.5.
15. The electronic apparatus according to claim 12 , wherein 1.6<P<2.6.
16. The electronic apparatus according to claim 12 , wherein 0.16<Q<0.45.
17. The electronic apparatus according to claim 12 , wherein a mass ratio of the first positive electrode material to the second positive electrode material is 5:1 to 99:1.
18. The electronic apparatus according to claim 12 , wherein based on a total mass of the positive electrode material layer, a percentage of the first positive electrode material is 80% to 98%.
19. The electronic apparatus according to claim 12 , wherein the first positive electrode material comprises at least one of LifePO 4 , LiFe 0.5 Mn 0.5 PO 4 , Li 0.9 Fe 0.5 Mn 0.45 Ti 0.05 PO 4 , Li 0.9 Fe 0.5 Mn 0.45 Ti 0.04 Zr 0.01 PO 4 , or Li 0.95 FePO 3.95 F 0.05 ; and/or the second positive electrode material comprises at least one of LiMnO 2 , LiMn 0.9 Ni 0.1 O 2 , LiMn 0.9 Ni 0.05 Cr 0.05 O 2 , Li 0.95 MnO 1.95 F 0.05 , or Li 0.95 MnO 1.9 S 0.05 F 0.05 .
20. The electronic apparatus according to claim 12 , wherein the electrolyte comprises vinyl carbonate; wherein based on a total mass of the electrolyte, a percentage of the vinyl carbonate is 0.05% to 5%.