Lithium ion batteries with long cycling performance
View Patent ↗Batteries with high energy and high capacity are described that have a long cycle life upon cycling at a moderate discharge rate. Specifically, the batteries may have a room temperature fifth cycle discharge specific energy of at least about 175 Wh/kg discharged at a C/3 discharge rate from 4.2V to 2.5V. Additionally, the batteries can maintain at least about 70% discharge capacity at 1000 cycles relative to the fifth cycle, with the battery being discharged from 4.2V to 2.5V at a C/2 rate from the fifth cycle through the 1000th cycle. In some embodiment, the positive electrode of the battery comprises a lithium intercalation composition with optional metal fluoride coating. Stabilizing additive maybe added to the electrolyte of the battery to further improve the battery performance. The batteries are particularly suitable for use in electric vehicles.
1. An electric vehicle comprising an electric motor, a drive train comprising wheels mounted on axles driven by the electric motor, a passenger compartment comprising seats and controls wherein the passenger compartment is supported at least in part by the drive train, and an electrical power pack comprising a plurality of lithium ion batteries wherein the power pack provides at least about 40 kWh of power and a volume of no more than about 128 liters and wherein the lithium ion batteries comprise:
a negative electrode, a positive electrode, a separator between the negative electrode and the positive electrode, and a non-aqueous electrolyte comprising lithium ions from a primary lithium salt comprising lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis(trifluoromethyl sulfonyl imide), lithium trifluoromethane sulfonate, lithium tris(trifluoromethyl sulfonyl) methide, lithium tetrafluoroborate, lithium perchlorate, lithium tetrachloroaluminate, lithium chloride or combinations thereof and a lithium salt stabilizing additive,
wherein the electrodes and separator are wound or the battery further comprises at least one additional negative electrode and one additional positive electrode in a stack configuration,
wherein the concentration of lithium salt stabilizing additive in the electrolyte is from about 0.01 weight percent to about 9 weight percent,
wherein the negative electrode comprises graphite and the positive electrode comprises from 92 wt % to 97 wt % of an active composition comprising a layered lithium metal oxide approximately represented by the formula Li 1+x Ni α Mn β Co γ O 2 , where x ranges from about 0.05 to about 0.15, α ranges from about 0.1 to about 0.4, β range from about 0.3 to about 0.65, and γ ranges from about 0.05 to about 0.4 and an inorganic coating, and
wherein the battery has a room temperature discharge specific energy of at least about 175 Wh/kg at a C/3 discharge rate for cycle 5 at a discharge from 4.2V to 2.5V and a cycle life with at least about 70% capacity at 1000 cycles relative to cycle 5 at a C/2 discharge from 4.2V to 2.5V for the fifth cycle through the 1000th cycle.
2. The electric vehicle of claim 1 wherein the plurality of lithium ion batteries comprise cylindrical 26700 type cells.
3. The electric vehicle of claim 1 wherein the plurality of lithium ion batteries comprise prismatic shaped batteries with a polymer pouch casing.
4. The electric vehicle of claim 1 wherein active composition of the positive electrode has a coating comprising a metal fluoride and wherein the plurality of lithium ion batteries comprise an electrolyte, the electrolyte comprising a stabilizing additive.
5. The electric vehicle of claim 1 wherein the lithium intercalation composition is approximately represented by the formula Li 1+x [M 0.333 Ni 0.333 Co 0.333 ] 1−x O 2 , wherein x is between about 0.05 and 0.125.
6. The electric vehicle of claim 1 wherein the lithium intercalation composition of the positive electrode has a coating comprising a metal fluoride.
7. The electric vehicle of claim 1 wherein the lithium salt stabilizing additive comprises a lithium(chelato)borate or lithium(chelato)phosphate.
8. The electric vehicle of claim 1 wherein the batteries further comprise a cylindrical metal case.
9. The electric vehicle of claim 1 wherein the batteries have a foil case and a prismatic shape.
10. The electric vehicle of claim 1 wherein the batteries have a room temperature discharge specific energy of at least about 195 Wh/kg at a C/3 discharge rate for cycle 5 at a discharge from 4.2V to 2.5V.
11. The electric vehicle of claim 1 wherein the batteries have a cycle life with at least about 70% capacity at 1100 cycles relative to cycle 5 at a C/2 discharge from 4.2V to 2.5V for the fifth cycle through the 1100th cycle.
12. The electric vehicle of claim 1 wherein the batteries have a room temperature energy density of at least about 425 Wh/L at a C/3 discharge rate for cycle 5 at a discharge from 4.2V to 2.5V.