Stabilized Alpha‐ MnO2 Electrodes for Rechargeable 3 V Lithium Batteries

Manganese dioxide electrodes that have x‐ray diffraction patterns characteristic of (hollandite‐type structure) and ramsdellite‐ have been evaluated in rechargeable 3 V lithium cells. Electrochemical data indicate that these electrodes (162 mAh/g, 10th cycle) provide superior performance to both single‐phase pure (136 mAh/g, 10th cycle) and ramsdellite‐ electrodes (113 mAh/g, 10th cycle), and comparable performance to lithia‐stabilized electrodes (153 mAh/g, 10th cycle). Transmission electron microscopy images and convergent‐beam electron diffraction patterns show that the samples consist of grains of α‐ grains of ramsdellite‐ , and grains of "interconnected" and ramsdellite‐ which exhibit a mutual crystallographic orientation. A search is underway to find other interconnected materials with even better cycling performance.