In the past few years, batteries that mostly used in emergency lighting are Ni-Cd battery, Ni-Mh battery and Lead acid battery. But there are heavy medals Cadmium and Lead respectively in Ni-Cd battery and Lead acid battery, and these two kinds of batteries have much lower energy density and larger sizes; As for Ni-Mh battery, it has worse performance of long term float charge, larger size, and higher price; thus more and more emergency lighting manufacturers are using lithium batteries on their products, and NMC lithium battery and LiFePO4 battery are most-used.
NMC lithium battery is cheaper than LiFePO4 battery, but with much worse safety performance; LiFePO4 battery is much more expensive than NMC lithium battery, but with much better safety performance. Even though LiFePO4 battery is much more expensive, considering the good safety performance, LiFePO4 is still widely used in foreign markets, like Europe, America and Australia; but because of the lower cost of NCM lithium battery, it is more widely used in China domestic market.