Electrochemical device and electronic device
An electrochemical device includes a negative electrode plate including a negative current collector provided with a negative active material layer and a positive electrode plate including a positive current collector provided with a positive active material layer. The positive active material layer includes a first region. The first region includes a second region and a third region that does not overlap the second region by any area. A first insulation layer is disposed on a surface of the second region. The negative active material layer includes a fourth region facing towards the third region. An area S2 mm 2 of the second region and an area S1 mm 2 of the first region satisfy: S2<S1≤1.5S2, and a ratio CB of a unit-area capacity of the fourth region to a unit-area capacity of the third region is greater than or equal to 1.1.
1 . An electrochemical device, comprising:
a negative electrode plate comprising a negative current collector, wherein the negative current collector comprises a first surface, and a negative active material layer is disposed on the first surface; and
a positive electrode plate comprising a positive current collector, wherein the positive current collector comprises a second surface facing towards the first surface, and a positive active material layer is disposed on the second surface;
wherein the positive active material layer comprises a first region, the first region comprises a second region and a third region, a first insulation layer is disposed on a surface of the second region, the third region is a region that does not overlap the second region by any area in the first region, and the negative active material layer comprises a fourth region facing towards and corresponding to the third region;
wherein a unit-area capacity of the third region is less than a unit-area capacity of the region of the positive active material layer different from the third region;
wherein a unit-area capacity of the fourth region is greater than a unit-area capacity of a region of the negative active material layer different from the fourth region;
wherein an area S2 mm 2 of the second region and an area S1 mm 2 of the first region satisfy a relation: S2<S1≤1.5S2, and a ratio CB of the unit-area capacity of the fourth region to the unit-area capacity of the third region is greater than or equal to 1.1.
2 . The electrochemical device according to claim 1 , wherein the region of the negative active material layer different from the fourth region comprises a first negative active material, a superficial layer of the fourth region comprises a second negative active material, and a gram capacity of the second negative active material is greater than a gram capacity of the first negative active material.
3 . The electrochemical device according to claim 2 , wherein a lithiation potential versus Li/Li + of the second negative active material is 0.2 V to 3.0 V.
4 . The electrochemical device according to claim 2 , wherein the second negative active material comprises at least one of transition metal oxide, lithium titanium oxide, graphene, hard carbon, soft carbon, silicon, silicon-oxygen compound, silicon-carbon compound, artificial graphite, natural graphite, mesocarbon microbead, phosphorus, or sulfur.
5 . The electrochemical device according to claim 2 , wherein a thickness of the superficial layer of the fourth region is less than or equal to 50 μm.
6 . The electrochemical device according to claim 1 , wherein a groove is provided in the negative active material layer, a negative tab is accommodated in the groove, the negative tab is electrically connected to the negative current collector, and a projection of the groove on the positive active material layer is located in the second region.
7 . The electrochemical device according to claim 6 , wherein the area of the second region is equal to an area of the groove.
8 . The electrochemical device according to claim 6 , wherein a second insulation layer is disposed on a surface of the negative tab, and a distance between a surface of the superficial layer of the fourth region facing opposite to the negative current collector and the negative current collector is less than or equal to a distance between a surface of the second insulation layer facing opposite to the negative current collector and the negative current collector.
9 . The electrochemical device according to claim 6 , wherein a surface of the negative tab is overlaid with the negative active material layer.
10 . The electrochemical device according to claim 1 , wherein the third region comprises a first positive active material, and a region of the positive active material layer different from the third region comprises a second positive active material.
11 . The electrochemical device according to claim 10 , wherein a gram capacity of the first positive active material is less than a gram capacity of the second positive active material.
12 . The electrochemical device according to claim 10 , wherein a thickness of the third region is less than a thickness of the region of the positive active material layer different from the third region.
13 . The electrochemical device according to claim 12 , wherein the third region is provided without the positive active material layer.
14 . The electrochemical device according to claim 1 , wherein the third region is adjacent to the second region, and the first insulation layer is disposed exclusively on the surface of the second region and does not extend onto a surface of the third region.
15 . An electronic device, comprising an electrochemical device, the electrochemical device comprises:
a negative electrode plate comprising a negative current collector, wherein the negative current collector comprises a first surface, and a negative active material layer is disposed on the first surface; and
a positive electrode plate comprising a positive current collector, wherein the positive current collector comprises a second surface facing towards the first surface, and a positive active material layer is disposed on the second surface;
wherein the positive active material layer comprises a first region, the first region comprises a second region and a third region, a first insulation layer is disposed on a surface of the second region, the third region is a region that does not overlap the second region by any area in the first region, and the negative active material layer comprises a fourth region facing towards and corresponding to the third region;
wherein a unit-area capacity of the third region is less than a unit-area capacity of the region of the positive active material layer different from the third region;
wherein a unit-area capacity of the fourth region is greater than a unit-area capacity of a region of the negative active material layer different from the fourth region;
wherein an area S2 mm 2 of the second region and an area S1 mm 2 of the first region satisfy a relation: S2<S1≤1.5S2, and a ratio CB of the unit-area capacity of the fourth region to the unit-area capacity of the third region is greater than or equal to 1.1.
16 . The electronic device according to claim 15 , wherein the region of the negative active material layer different from the fourth region comprises a first negative active material, a superficial layer of the fourth region comprises a second negative active material, and a gram capacity of the second negative active material is greater than a gram capacity of the first negative active material.
17 . The electronic device according to claim 16 , wherein a lithiation potential versus Li/Li + of the second negative active material is 0.2 V to 3.0 V.
18 . The electronic device according to claim 15 , wherein a groove is provided in the negative active material layer, a negative tab is accommodated in the groove, the negative tab is electrically connected to the negative current collector, and a projection of the groove on the positive active material layer is located in the second region.
19 . The electronic device according to claim 15 , wherein the third region comprises a first positive active material, a region of the positive active material layer different from the third region comprises a second positive active material.