Aluminum Alloy Produces Thin Lithium Ion Rechargeable Cell
Previous efforts to produce batteries thinner than 3 mm were accomplished using aluminum laminated films to produce a soft case which is mechanically weak. The new Maxell cells use a harder aluminum alloy material containing 4.5% magnesium to achieve a lighter and harder case that does not crack and can't be damaged with a pin or scissors. The hard aluminum alloy material, which contains more than 0.6% Magnesium, was not used for the Li-Ion battery, since it has a tendency to crack at the welded part. However a recent study shows that when the Magnesium content is increased to nearly 4.5%, it will become the same level of current aluminum can as far as welding is concerned.
An important new structural feature is a 1.3-mm rib, which surrounds the cell, carrying protective circuitry and aiding in positioning. The rib serves as the base of a simplified battery pack and helps package the cell into the plastic case of the battery pack.
The IC283465G prismatic cell has a nominal voltage rating of 3.7 volts, weighs 16 grams and measures 2.8 mm in thickness by 34 mm in width and 65 mm in height. Maximum charge voltage is 4.2 volts, with a maximum current of 0.6 amps, while the end voltage at discharge is 2.75 volts at a maximum current of 0.90 amps.
Nominal capacity is 630 mAh, with a minimum of 600 mAh, when conditions of charge are CCCV:1 C/4.2 V 3 h and discharge are 0.2 C/E.V = 2.75 V. Energy density is 359 Wh/liter and weight is 139 Wh/kg.