Lithium-ion battery for electronic applications

Lithium-ion (rocking-chair) batteries with lithiated metal oxide cathodes and carbon anodes are finding use in many emerging electronic applications with current drains ranging from a few microamperes (e.g., memory backup, real-time clock, bridge function) to many milliamperes (e.g., laptop computers, phones, etc.). The majority of these applications (e.g., coin, cylindrical, prismatic cell configuration) require a steady low current with periodic high drain pulses. We have found that lithium-ion systems based on lithiated nickel oxide cathodes (LiNiO2) and carbon anodes can be tailored for high capacity moderate rate or moderate capacity high rate applications. In the first instance, a graphitic carbon anode and ethylene carbonate-based electrolyte (e.g., ethylene carbonate-dimethyl carbonate (EC-DMC)) has proven effective while in the second case a petroleum coke anode and propylene carbonate-based electrolyte (e.g., propylene carbonate-dimethoxyethane (PC-DME)) look best. An unoptimized, experimental LiNiO2/LiPF6, EC-DMC/graphitic carbon, AA-cell has delivered 620 mAh at 0.1 mA cm−2 but the capacity then dropped to 535 mAh at 1 mA cm−2 and 375 mAh at 3 mA cm−2. Efforts are under way to improve the rate capabilities of cells incorporating graphitic carbon anodes. Initial results indicate that microfiber graphite, special electrolytes and in-house prepared LiMxNi1−xO2 compounds will achieve the desired performance levels.