An X‐Ray Diffraction, Scanning Electron Microscopy Study of Separator Failure

Abstract

cell was the best, and that of the platinum was the worst.2. The main components of the exhaust gas were nitrogen and hydrogen. A little ammonia was detected when the operating temperature was 60~ 3. The hydrogen content of the exhaust gas decreases and fuel efficiency increases in accordance with increases in the current density. At a high current density, it is presumed that hydrogen which is produced by side reaction is caught by the anode and is used for further reaction.4. The hydrogen content of the exhaust gas increases and fuel efficiency decreases with increasing hydrazine concentration. It seems that the decomposition of hydrazine which is not used effectively for electrochemical reaction increases with increasing hydrazine concentrations.5. The hydrogen in exhaust gas increases and fuel efficiency decreases with increasing cell temperatures. ABSTRACTResin-bonded paper separators suffer some loss of crystalline material on extended storage in battery grade H2SO4. Similar separators from cycled batteries suffer order of magnitude losses of crystallinity. Scanning electron microscopy has found Pb-salts of two kinds; those grown in regions of high and low supersaturation. The latter often obtain crystal dimensions larger than 30~. Comparison with other separator materials used in Pb/acid batteries has led to a model of separator failure based on mechanical abrasion, fluid motion, and crystallization in large pores. The separator matrix is weakened by brittle fracture of the fiber network, accompanied by minor hydrolytic loss of material. These lead in turn to pore enlargement that can enhance the growth of large, well-ordered crystals. A somewhat speculative mechanism for perforation failure of large-pored separators is given. * Electrochemical Society Active Member.

Resin‐Bonded Cellulose Separators: An Overview with Prognoses

“…Figure 5 shows the pore size distribution (PSD) of three matrixes: wood, fine filter paper, and coarse filter paper (137). The PSD of the coarse filter is very similar to the PSD found for RBC separators (75,133). Wood veneer is known to be a superior separator for lead-acid applications, so these data suggest that an impregnated finepore paper matrix will approach wood in performance.…”

“…Its dominance in the automotive battery industry, that most numerous and profit stimulating of lead-acid batteries, has inadvertently placed it in a limbo from which it promises never to come forth. Recent work in separator technology (87,133) indicates that the problem of RBC separator failure is a complex problem associated with the fundamental paper matrix and with the nature of the impregnation.…”

“…The paper matrix--Pore size distribution.--Palmer (52), Sundberg (75), and others (133) argue effectively that pore size distribution in the separator is the principal variable in considering failure, whether due to antimony transfer or so-called perforation failure. It has been shown (133) that large pore separators most frequently fail by the perforation mechanism and offer an excellent matrix for capture and growth of suspended and dissolved lead species, and Sundberg (75) has argued that large pore matrixes permit greater transport of antimony from the positive grid to the negative, placing the blame on antimony diffusion. Diffusive transfer should be practically the same whatever the separator or barrier; however, the electrolyte in a cycling cell is subject to a great deal of stirring during charge and overcharge.…”

Diagnostic Studies of Polyolefin Separators in High-Power Li-Ion Cells

“…The salt deposits reduced the size of the separator pores and eventually bridged pores together, leading to cell shorts. 19 The reliability of the separator is thus critical for the proper and continued functioning of the cell. There is little reported work on the polyolefin separators used in lithium-ion cells, and their reliability during long-term testing has not been investigated in detail via detailed diagnostic characterization.…”