锂离子电池的失效模式.pdf

Li ion failures Cause Prevention IEEE 1625 Sept 25 Shorts on cathode coating generally benign Rc Al + Cathode Rs - Anode Z Cu Ra • Z ~ 15 mohm, Ra Rc ~ 100 ohm for sub mm size short • Rc limits current, localized heating • Normal self-discharge and Li dendrites fall in this category IEEE 1625 Sept 25 Exception: Large shorts on cathode coating Rc Al + Cathode Rs - Anode z Cu Ra • Particles large enough to substantially penetrate the cathode coating are dangerous IEEE 1625 Sept 25 Shorts from bare Al to coated anode Rc Al Rs - Anode z Cu Ra • Cathode coating does not limit the power dissipation, local heating can easily melt the Al IEEE 1625 Sept 25 Small shorts become large as bare Al melts Even if initial short ‘burns out’ molten Al keeps shorting Example: produce small short in the bare Al section of Mn power cells -I’ve seen Al foil melt back to edge of cathode and the Al tab IEEE 1625 Sept 25