Several commercial grade electrolytic manganese dioxides (EMD's) of gamma variety were converted to
normalbeta‐MnO2
by digesting in 1M sulfuric acid containing Mn2+ at various temperatures. The transformation was found to be catalyzed by Mn2+ and accelerated at high temperatures. The pseudo first‐order rate constants of EMD transformation were evaluated and an activation energy determined to be in the range of 98–115 kJ/mol. This value was very close to the activation energy of 94–100 kJ/mol for desorption of the type II water in EMD lattice. A mechanism involving the equilibrium between EMD and Mn2+, and liberation of the bound water was, thus, proposed.
New electrolyte salts based on the reaction between
NbCl5
and either
Li2S
or
Li2O
in
SOCl2
substantially reduce voltage delay in laboratory half‐cells. The maximum effect was obtained with the
NbCl5/Li2S
combination. The conductivity of both electrolytes is
13.2×10−3 mho cm−1
at 26°C. Observations with scanning electron microscopy (SEM) show that the anode film formed in the new electrolyte has a different morphology and appears less dense than the film formed in control
LiAlCl4
electrolyte. The anodic rate capability of Li is slightly greater, over a range of over‐potentials, in the
normalNbCl/Li2S
electrolyte than in
LiAlCl4
. Atomic absorption, infrared, and x‐ray photoelectron spectroscopy and electrochemical analysis suggest that the salt formed by reacting
NbCl5
with
Li2S
in
SOCl2
is either
Li2Nb2Cl10S
or
Li2Nb2Cl12
. The mechanism for reducing voltage delay and affecting anode film morphology is thought to be associated with the nature of the salt's anion, or possibly the
SO2
produced when
Li2S
is combined with the
NbCl5
in
SOCl2
.
Industry has dictated a growing need for cells and batteries capable of sustained use and storage in elevated temperature environments. This usage varies from short term exposures for surface mount technology, to the long term service environments of the automotive industry for computer memory backup.The storage temperature for typical lithium carbonmonofluoride (Li/CFx) cells range from -40°C to +6OoC. Accelerated thermal testing has identified three primary failure modes for the standard design as: electrolyte diffusion through the seal, degradation of the polymeric seal material, and internal component corrosion/degradation. All three of these failure modes are essentially related.The electrochemical couple itself should be capable of functioning up to 181°C for the lithium and 450-650°C for the carbon-monofluoride. The lithium of this cell system can further be modified by alloying for increased thermal stability.(Li/CFx) coin cell system has been optimized for high temperature (1 25°C) applications. The optimization was accomplished utilizing the standard BR1225 cell size as a test vehicle. An unique electrolyte formulation and polymeric seal material have resulted in cells that tolerate temperatures up to 125°C for a year without substantial degradation in performance.
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