Prospects for thin film lithium batteries

Lithium batteries have steadily increased in usage over the last three decades from primary, low-current supplies for heart pacemakers to the fast-cycling rechargeable batteries used in mobile phones. Lithium is particularly suitable as the negative electrode of a battery for the following reasons: a lithium negative electrode stores charge at high volumetric and very high gravimetric density according to the following data; many positive electrode compounds exist in which lithium can be reversibly stored in a state of very low energy compared to lithium metal; and lithium ions have a high mobility in certain solid electrolytes. Assuming the electrolyte thickness can be made negligible compared with the electrodes, the positive electrode places a theoretical limit on the energy density of about 600 Wh kg^-1 or 1500 Wh dm^-3 for a Li/Mn₂O₄ cell. The author briefly shows that thin film lithium batteries can be fabricated using processes compatible with semiconductor technology to produce a useful amount of reversible on-board or on-chip energy storage. Present specifications could be improved with further development