Batteries with Nanocrystalline Li_xMn_2-yO₄ Cathodes

These batteries are well suited for applications requiring low current densities of less than 50 µA/cm². The cathodes are deposited at ambient temperature by rf magnetron sputtering of LiMn₂O₄ and require no post-deposition anneal. Since the remaining battery components are also deposited at low temperatures, Li-n Li_xMn_2-yO₄ batteries can be fabricated onto low-melting flexible polymer substrates. The as-deposited cathode films are dense, nanocrystalline, and have a Mn deficient composition near Li₄Mn₅O₁₂.

Features:

• The specific capacity of the cathode film is ~145 mAh/g for 4.5 to 2.5 V, and ~270 mAh/g when discharged to 1.5 V.
• The secondary performance is comparable to cells with LiCoO₂ cathodes.
• The batteries can be cycled at 100°C. Although the cathode gradually becomes more crystalline, these results highlight the stability of the Lipon electrolyte at 100°C.

A high specific capacity, >100 µA/cm²•µm of cathode, is available at potentials between 4 V and 1.5 V

Discharge curves at different current densities at 25 and 100°C

Specific capacity vs. current density for cycling between 4.5 and 2.5 V at 25 and 100°C.