Lithium aluminum manganese oxide (LAMO) having a spinel-framework structure (a=8.211 A) was prepared and examined in lithium nonaqueous cells. LAMO shows extremely small irreversible capacity with rechargeable capacity of ca. 105 mAh g(-1) in lithium cells operated in voltage of 3 to 5 V. To show durability for long-life applications, a 2.5 V lithium-ion cell of Li[Li1/3Ti5/3]O-4 and LAMO was fabricated and accelerated cycle tests were done at room temperature in voltage of 2 to 3 V for 3600 cycles, and an empirical relation between capacity (Q) and number of cycle (n) was obtained to be Q=102.7-0.144 n(1/2). (c) 2006 The Electrochemical Society.