Catalytic electrolyte decomposition

Catalytic Reactions in Lithium-ion Cells Catalytic Electrolyte Decomposition— an Undesired Surface Reaction... 

FIGURE 17.7 The decomposition products of the organic carbonate solutions containing liPFs (top insert) and auto-catalytic electrolyte decomposition cycle in lithium-ion cells. 

The thermal stabilizing properties of the electrode materials were foimd to be the result of reactions of the electrolyte or electrolyte decomposition products with the surface of the electrodes. Two primary mechanisms were proposed to be responsible for this stabilization. First, the electrode materials could react with the auto-catalytic species rapidly, preventing the exponential decomposition. Second, the surface species could Lewis basic species and reversibly bind the free PF5, preventing the electrolyte decomposition [32,34],... 

S. Pancharatnam, R.A. Huggins, and D.M. Mason, Catalytic Decomposition ofNitric Oxide on Zirconia by Electrolytic Removal of Oxygen, J. Electrochem. Soc. 122(7), 869-875(1975). 

In addition to the universal concern for catalytic selectivity, the following reasons could be advanced to argue why an electrochemical scheme would be preferred over a thermal approach (i) There are experimental parameters (pH, solvent, electrolyte, potential) unique only to the electrode-solution interface which can be manipulated to dictate a certain reaction pathway, (ii) The presence of solvent and supporting electrolyte may sufficiently passivate the electrode surface to minimize catalytic fragmentation of starting materials. (iii) Catalyst poisons due to reagent decomposition may form less readily at ambient temperatures, (iv) The chemical behavior of surface intermediates formed in electrolytic solutions can be closely modelled after analogous well-characterized molecular or cluster complexes (1-8). (v)... 

In this configuration, the membrane is selective to some reactants or products and the catalyst may be placed on the membrane surface or near the pore entrance such as catalytic electrodes attached to solid electrolytes or a platinum layer on the surface of a vanadium membrane as the catalyst for thermal decomposition of hydrogen sulfide [Edlund and Pledger, 1993]. Solid or liquid catalysts have been attached to membranes or their pores. It has been mentioned previously that this configuration can also be used to control the addition of a reactant through the membrane pores from the other side of the membrane where the second reactant is introduced. 

Saracco and Specchia [84] noted that inorganic membranes have great potential in gas separation, catalytic reactors, gasification of coal, water decomposition, and solid electrolyte fuel cells [81-89]. Inorganic membranes are usually made from alumina, sUica, carbon, and zeolites [85]. We will only assess porous membranes since fouling is virtually absent in dense membranes [81]. 

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