Abstract:
A primary lithium electrochemical cell housed in a casing having a curved side wall intermediate opposed generally planar face walls is described. The cell comprises an anode and a cathode that each has a plurality of face portions joined together by connecting portions. The opposite polarity face portions and connecting portions are aligned with each other and then the electrodes are wound to provide an electrode assembly that fits in the casing. Regardless whether the cell is balanced as either an anode-limited or cathode-limited configuration, however, it is desirable to have the active material of one electrode face portion directly facing the electrode material of the counter electrode face portion. This means that the dimensional extent of the facing electrodes should be as close to each other in areas as possible to match the desired anode- or cathode-limited balance. The same is true for the connecting portions. The cell is of a high energy density for an implantable biomedical device.
Abstract:
Heat generation is an important concern of electrochemical cell design. The invention is directed toward a cell design that efficiently and responsively dissipates heat by transfer from the cell to the casing through multiple parallel connections. This invention relates to battery designs having cell stacks in which both the anode and cathode are of a plate structure and the anode plates are independently connected to the cell casing or connected thereto via a bridge or bus. They may also consist of cell assemblies of wound electrode configurations or plate-serpentine configurations having multiple parallel connections to the cell casing. Surface area is an important criterion in battery design since it increases the current draw capability of the battery. The total surface area of this cell is potentially larger than any of the above mentioned types without sacrificing safety since the rate of heat conduction along the electrode pathway is approximately proportional to half an individual plate length, rather than the total anode length. Also, since the rate of heat leaving the cell is in excess of that found in traditional, galaxy or cathode plate and serpentine anode types of cells, the probability of cell venting is minimal.
Abstract:
A drop-fill assembly and method for uniformly distributing electrode active particles onto a current collector is described. The drop-fill assembly comprises a conduit containing two or more spaced apart sifting screens. A funnel is located upstream of the sifting screens to distribute an electrode active powder into the center of the conduit with a downward velocity. The mesh of any one sifting screen is out of direct alignment with respect to the next or previous screen. The electrode active powder is poured into the funnel and distributed across the conduit's cross-section as it bounces off and passes through the misaligned sifting screens. The powder exits at the bottom of the conduit lying in a thin, uniform layer on a current collector, taking on the shape of the desired electrode due to the boundary of the conduit and pressing fixtures located above and beneath the current collector. The powder layer is then pressed on to the current collector to produce an electrode.