Long-life and ultra-high energy density lithium secondary battery
A lithium secondary battery, wherein there is a pre-lithiated negative electrode such that a total irreversible capacity of a positive electrode is greater than a total irreversible capacity of the negative electrode while satisfying 150< (negative electrode discharge capacity/lithium secondary battery discharge capacity)×100<300, and a relative potential of the negative electrode with respect to lithium metal in an operating voltage range of the lithium secondary battery is in a range of −0.1 V to 0.7 V. Such a lithium secondary battery is capable of maintaining a capacity retention of 60% or more even after 500 cycles or more while achieving an energy density per volume of 800 Wh/L or more.
1. A lithium secondary battery, comprising:
a negative electrode;
a positive electrode;
a separator; and
an electrolyte,
wherein the negative electrode comprises:
a current collector;
a pair of negative electrode active material layers comprising a negative electrode active material, disposed on both surfaces of the current collector;
a pair of first layers disposed on respective surfaces of the negative electrode active material layers opposite the current collector, wherein the pair of first layers comprise lithium; and
a pair of second layers disposed on respective surfaces of the first layers, wherein the pair of second layers comprise an inorganic material,
wherein each of the first layers has a thickness of 2.5 μm to 4.5 μm and each of the second layers has a thickness of 100 nm to 200 nm,
wherein a total irreversible capacity of the positive electrode is greater than a total irreversible capacity of the negative electrode while the lithium secondary battery satisfies Equation 1, and
a relative potential of the negative electrode with respect to lithium metal in an operating voltage range of the lithium secondary battery is in a range of −0.1 V to 0.7 V:
150<(negative electrode discharge capacity/lithium secondary battery discharge capacity) x 100<300 Equation 1
wherein, the negative electrode discharge capacity is a value measured by preparing a coin half-cell which includes the negative electrode, as a positive electrode, and the lithium metal as a negative electrode.
2. The lithium secondary battery of claim 1 , wherein the relative potential of the negative electrode with respect to the lithium metal in the operating voltage range of the lithium secondary battery is in a range of 0 V to 0.6 V.
3. The lithium secondary battery of claim 1 , wherein each of the first layers has a thickness of 3.0 μm to 4.0 μm.
4. The lithium secondary battery of claim 1 , wherein the negative electrode active material has a capacity of 1,000 mAh/g or more.
5. The lithium secondary battery of claim 1 , wherein the negative electrode active material comprises at least one selected from the group consisting of silicon, tin, titanium, aluminum, lead, zinc, bismuth, indium, magnesium, gallium, and cadmium.
6. The lithium secondary battery of claim 1 , wherein the positive electrode comprises a positive electrode active material represented by a formula of LiNi 1-a M a O 2 , wherein M is at least one selected from the group consisting of cobalt, manganese, aluminum, copper, iron, magnesium, boron, and gallium, and a satisfies 0.01≤a≤0.3.
7. The lithium secondary battery of claim 1 , wherein the inorganic material comprises at least one selected from the group consisting of Al 2 O 3 , SiO 2 , and ZrO 2 .
8. The lithium secondary battery of claim 1 , wherein the lithium secondary battery has an energy density per volume of 800 Wh/L or more.
9. The lithium secondary battery of claim 1 , wherein a capacity retention of the lithium secondary battery is maintained at 60% or more after 500 cycles or more.