AN UPDATE OF THE LI METAL-FREE RECHARGEABLE BATTERY BASED ON LI1+XMN2O4 CATHODES AND CARBON ANODES

We report on a rocking-chair cell using the manganese oxide spinel (Li1+xMn2O4) as the positive electrode and carbon as the negative electrode, and detail its electrochemical behavior as a function of charge cutoff voltage, current rate, operating temperature, and the ratio of positive and negative electrode masses. Recently, the Li ion (Li1+xMn2O4/electrolyte/carbon) laboratory test cells were optimized using a newly discovered liquid electrolyte system that (i) is compatible with the LiMn2O4 positive electrode up to oxidation voltages of 5 V versus Li, and (ii) allows the use of petroleum-coke or graphite as the negative electrode. With this new electrolyte, the 3.7 V Li1+xMn2O4/carbon cells are readily reversible and show high specific energies (3 times more than Ni-Cd), high power rate capability, and promising cycle life even at 55-degrees-C. 'AA' lithium metal-free rechargeable cells based on the Li1+xMn2O4/new electrolyte/carbon system were constructed for safety and performance evaluations. The unoptimized 'AA' cells are safe, have excellent rate capability and a capacity of approximately 0.35 A h.