EFFECT OF PR CONTENT IN ML ON THE ELECTROCHEMICAL PROPERTIES OF ML(NI-CO-MN-AL)(5) ALLOYS

The electrochemical properties of MINi(3.5)Co(0.8)Mn(0.4)Al(0.3) alloy s with various Pr contents in MI were studied in this work, It was fou nd that the Pr content in MI obviously affected the electrochemical pr operties of MI(Ni-Co-Mn-Al)(5) alloys. The electrochemical properties were greatly improved if the electrode alloy contained about 20 at.% P r in MI. The electrode made from this alloy has a higher capacity, bet ter discharge rate characteristics and longer cycle life than that fro m alloy with less than 10 at.% Pr in MI, as in common misch metal. The AA size cells in which electrode alloy contains about 17 at% Pr in MI are also studied. It was found that these cells have a very long cycl e life (1400 cycles) with reasonable capacity (1250 mA h) and rate cap ability (1100 mAh) when discharged at 5 C). In particular, they have a very superior low temperature capability. For example, their capacity was higher than 1050 mA h when discharged at 1C and -18 degrees C.