LITHIUM-ION BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRIC DEVICE
Provided are a lithium-ion battery, including a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, wherein in the battery, a ratio of a negative electrode capacity to a positive electrode capacity is a, and the electrolyte includes thiourea compounds in an amount of b weight % based on the total weight of the electrolyte, wherein the lithium-ion battery meets the following relationship: a<1.05; and 25×(1.05−a)≤b≤100×(1.05−a). Due to the presence of a specific amount of thiourea compounds in the electrolyte, the battery has a lower CB value and, at the same time, exhibits good cycle performance.
1 . A lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, wherein
in the battery, a ratio of a negative electrode capacity to a positive electrode capacity is a, and the electrolyte comprises thiourea compounds in an amount of b weight % based on a total weight of the electrolyte, wherein the lithium-ion battery meets a following relationship:
a
<
1
.05
;
and
25
×
(
1
.05
-
a
)
≤
b
≤
1
0
0
×
(
1
.05
-
a
)
.
2 . The lithium-ion battery according to claim 1 , wherein a/b is in a range of 0.8 to 2.
3 . The lithium-ion battery according to claim 1 , wherein a is in a range of 0.9 to less than 1.05.
4 . The lithium-ion battery according to claim 1 , wherein b is in a range of 0.2 to 5.
5 . The lithium-ion battery according to claim 1 , wherein the thiourea compounds comprise a following structural formula:
where R and X are each independently selected from H, an alkyl of C1-C10, an alkenyl of C1-C10, a phenyl, or R and X together represent an alkylene of C1-C10 or an alkenylene of C1-C10, wherein the alkylene of C1-C10 or the alkenylene of C1-C10 is optionally substituted with an oxygroup; optionally, R and X are each independently selected from H, an alkyl of C1-C6, an alkenyl of C1-C6, or R and X together represent an alkylene of C1-C6 or an alkenylene of C1-C6.
6 . The lithium-ion battery according to claim 1 , wherein the electrolyte further comprises an additive selected from at least one of metal nitrates, a fluorinated vinyl carbonate, and a vinylene carbonate; optionally, the metal nitrates is one or more of lithium nitrate, magnesium nitrate, and copper nitrate; and optionally, a content of the additive is in a range of 0.5 weight % to 2 weight %, based on a total mass of the electrolyte.
7 . The lithium-ion battery according to claim 1 , wherein a thickness of a negative electrode film layer is ≤140 μm within the negative electrode sheet of the lithium-ion battery.
8 . A battery module, wherein the battery module comprises the lithium-ion battery according to claim 1 .
9 . A battery pack, wherein the battery pack comprises the battery module according to claim 8 .