Lithium-ion battery for electronic applications

Abstract

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 (LiNiO 2) 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 LiNiO 2/LiPF 6, 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 LiM x Ni 1− x O 2 compounds will achieve the desired performance levels.