6 Lithium-ion Battery Types —— Lithium Iron Phosphate(LFP)

Lithium phosphatehas good electrochemical performance and low resistance. This is achieved through nanoscale phosphate cathode materials. The main advantages are high rated current and long cycle life; Good thermal stability, enhanced security and tolerance to abuse. If kept at a high voltage for a long period of time, lithium phosphate is more tolerant to full charging conditions and is less stressed than other lithium ion systems. The disadvantage is that the lower nominal voltage of 3.2V batteries makes the specific energy lower than that of cobalt-doped lithium ion batteries. Lithium phosphate has a higher self-discharge than other lithium-ion batteries, which may cause aging and thus equalization problems, although this can be offset by the use of high-quality batteries or advanced battery management systems, both of which increase the cost of the battery pack. Battery life is very sensitive to impurities in the manufacturing process and cannot withstand water doping. Due to the presence of water impurities, some batteries have a minimum life of only 50 cycles.

By connecting four lithium phosphate batteries in series, the voltage of each battery is 3.60V, which is the correct full-charge voltage. At this point, it should be disconnected from the charge, but continue to charge while driving. Lithium phosphate tolerates some overcharging; However, as most vehicles maintain a voltage of 14.40V for a long period of time during long journeys, this may increase the mechanical stress of lithium phosphate batteries. Time will tell us how long lithium phosphate can withstand overcharging as an alternative to lead-acid batteries. Low temperatures also reduce lithium ion performance, which may affect the starting capacity in extreme cases.