Patent EP-0940866-A2 (EP)
Inventor: MOY GREGORY SCOTT
IPC: H01M4/02
Filed: 1999-03-08
Abstract: An elongate, generally tubular, air depolarized
electrochemical cell (10) comprising a cathode (14),
including an air cathode assembly (26), extending about the
tubular circumference, and along the tubular length, of the
cell (10), an anode (12), a separator (16) between the
anode (12) and the cathode (14), electrolyte, a top closure
member (177, 200), and a bottom closure member (114, 202).
The cathode assembly (26) is fixedly held, by a friction
fit, in a slot (116) at the bottom of the cell. The slot
can be developed, for example, by inner (110) and outer
(114) walls of a cathode can (28), by inner (226) and outer
(224) walls of a bottom closure member (202), or by an
outer wall (114) of a cathode can (28) and an opposing
outer wall of a plug (128) on the interior of the cell.
Preferably, bottom closure structure of the cell (10) and
receives a bottom edge portion (44) of the cathode current
collector (32), and makes electrical contact with the
bottom edge portion (44), preferably at an inner surface
(60) of the cathode current collector. A diffusion member
(36) of the cathode assembly (26) is preferably compressed
as a seal, at the bottom of the cell (10), between an outer
side wall (39) of the cell and the remainder of the cathode 
assembly (26). The diffusion member (36) is also used at
least as an assist in sealing the cell (10) against
electrolyte leakage from the anode cavity (137) and past
the cathode assembly (26). 
     The current collector (32) can be cylindrical and can
be free from longitudinal jointing, or can have a
longitudinal joint (54), preferably free from overlap of
the side wall. The current collector (32) can comprise an
imperforate edge region at the top (42) and/or bottom (44),
left (48) and/or right (46) edge. The perforations (56)
define an open fraction of the wall, of about 45 to about
70 percent. Typical cathode assemblies (26) have air
diffusion member (36) on the outer surface of the cathode
assembly (26). Such air diffusion member (36) typically
has thickness of about 0.0025 to 0.005 inch (about .06 to
about .13 mm.), and comprises a reduced thickness endless
wrap extending at least 1.5 times, preferably 2 times, or
3 times, about the current collector (32), discouraging
transfer of moisture vapor into or out of a cell,
discouraging leakage, and controlling air diffusion rate.
The diffusion member (36) extends beyond the top edge (42)
of the current collector, and is folded in and down about
the top edge (42) and inner surface (60) of the cathode
assembly (26). The cathode current collector (32) can be
mounted on a mandrel (93), the carbon sheet (80) passing 
through a nip defined between (i) support structure (192)
having greater arc radius than the mandrel (93) and (ii)
the mandrel (93), and applying force at the nip to
consolidate the carbon (80) onto the side wall (58),
passing air diffusion material (36) through the nip, and
applying force to consolidate the air diffusion material
(36) onto the carbon (80). The invention contemplates
fabricating an air cathode assembly (26) comprising
mounting the current collector (32) on a mandrel (93),
defining an arc having a radius smaller than the arc of the
cathode current collector (32), mounting the combination
mandrel (93) and cathode current collector (32) in a stack
(90) of assembly rolls (90A, 90B, 90C, 90D), making a sheet
stack of carbon sheets (80s, 80B, 80C, 80D), passing the
sheet stack through a nip, and applying force to the stack,
reducing thickness of the stack, and passing air diffusion
material (36) through the nips and applying force to
consolidate the diffusion material (36) onto the carbon
(80).