The Li-ion cell, Li4Ti5O12//PAN electrolyte//LiMn2O4, appears to be a classic example of a battery with passivation-free electrodes. Its gross impedance characteristics remain steady during long-term cycling at high charge/discharge rates. The cell showed excellent rechargeability at >99.9% coulombic efficiency for nearly 250 full-depth cycles, at a 1C discharge rate and a C/5 charge rate. The capacity fade was low at approximately 0.12% per cycle at around 100 cycles and similar to 0.05% at around 200 cycles. Excellent utilizations of the cathode and anode were observed with values of 100 mAh/g of LiMn2O4 and 140 mAh/g of Li4Ti5O12 at 1C discharge rate, and 70 mAh/g of LiMn2O4 and 92 mAh/g of Li4Ti5O12 at 7.5C discharge rate. Electrode utilizations were significantly better under pulse discharge conditions at the 8C-16C rates. The energy density of the cell, calculated with a cell voltage of 2.6 V and practically observed cathode and anode capacities at the C/10 discharge rate, is 60 Wh/kg. The weights of the electrodes, current collectors, and electrolyte are included in this value. It is suitable for applications where high power and very long cycle life are required.