Patent ID: 7348101

Claim:
A secondary lithium battery, comprising: a positive electrode comprising a layer on a positive electrode current collector, said layer comprising particulate conductive additive and a lithium transition metal phosphate having an olivine structure and having a thickness of about 50 μm to about 125 μm, and said positive electrode having a specific surface area of greater than 10 m 2 /g and a total pore volume between about 40% and about 60% by volume; a negative electrode comprising a layer on a negative electrode current collector, said layer comprising conductive additive and carbon and having a thickness of about 20 μm to about 75 μm, the carbon having an average particle size of less than about 25 μm, and said negative electrode having a total pore volume between about 25 and 40% by volume; a microporous electronically insulating high rate separator disposed between and in ionic contact with the cathode and the anode; and an electrolyte in ionic contact with the anode and the cathode, wherein the cell has a total area specific impedance, and the positive and negative electrodes each have an area specific impedance and the area specific impedance of the positive electrode is greater than the area specific impedance of the negative electrode, wherein during charging at greater than or equal to 4C, the negative electrode potential is above the potential of metallic lithium.