Non-aqueous electrolyte secondary cell
View Patent ↗A non-aqueous electrolyte secondary cell which achieves satisfactory low temperature characteristics and high safety against overcharging in combination. The cell includes a lithium-containing cathode, an anode capable of doping and undoping lithium, a non-aqueous electrolyte and a separator. The separator is made up by a plurality of layers of a porous material or materials presenting micro-sized pores. The layers of the porous material or materials is formed of micro-porous separator materials representing different combinations of the porosity, melting point or material/compositions.
1. A non-aqueous electrolyte secondary cell comprising:
a cathode comprising a lithium-containing cathode active material;
an anode comprising an anode active material capable of doping and undoping lithium;
a non-aqueous electrolyte; and
a separator comprising a plurality of layers of a microporous polyolefine material, wherein,
at least two microporous polyolefine material layers have different porosity values and include a highest porosity layer proximate to the anode and a lowest porosity layer proximate to the cathode during discharge of the cell,
the highest porosity layer has an average pore diameter of 0.1 μm to 1.0 μm and a porosity value B of 45%,
the lowest porosity layer has a thickness of 2% to 55% of the separator thickness, an average pore diameter of 0.03 μm to 0.2 μm, and a porosity value A of 25%
a porosity ratio A/B is 44% to 93%, and
at least one microporous material layer is of a resin coating material on one of the plurality of layers that has dried in situ.
2. The non-aqueous electrolyte secondary cell of claim 1 , wherein the porosity ratio A/B is 56% to 93%.
3. The non-aqueous electrolyte secondary cell of claim 1 , wherein the lowest porosity layer and the highest porosity layer are of different materials.
4. The non-aqueous electrolyte secondary cell of claim 1 , wherein the lowest porosity layer has a shutdown effect.
5. A non-aqueous electrolyte secondary cell comprising:
a cathode comprising a lithium-containing cathode active material;
an anode comprising an anode active material capable of doping and undoping lithium;
a non-aqueous electrolyte; and
a separator comprising a plurality of layers of a microporous polyolefine material, wherein,
at least two microporous polyolefine material layers have different porosity values and include a highest porosity layer proximate to the anode and a lowest porosity layer proximate to the cathode during discharge of the cell,
the highest porosity layer has an average pore diameter of 0.1 μm to 1.0 μm and a porosity value B of 45%,
the lowest porosity layer has a shutdown effect and has a thickness of 2% to 55% of the separator thickness, an average pore diameter of 0.03 μm to 0.2 μm, and a porosity value A of 25%, and
a porosity ratio A/B is 44% to 93%.
6. The non-aqueous electrolyte secondary cell of claim 5 wherein the lowest porosity layer and the highest porosity layer are of the same material.
7. The non-aqueous electrolyte secondary cell of claim 5 wherein the lowest porosity layer and the highest porosity layer are of different materials.