деградация

Structure of thin-film electrodes manufactured by layer-by-layer magnetron sputtering of Si and Al in the environment with small oxygen additives has been studied. Charge-discharge behavior of these electrodes was studied as well. It is shown that such electrodes are able to stable cycling with marginal irreversible capacity. 

The correlation between the Coulombic efficiency and the change in the residual capacity of electrodes and batteries under conditions without any parallel irreversible reactions was formulated. It was shown that this relationship allows drawing certain conclusions regarding the nature of degradation processes during cycling.

It is shown that an examination of reduced galvanostatic charge-discharge curves allows making preliminary conclusion on degradation mechanism upon cycling. If such degradation is due to loss of active material all normalized curves coincide. In the case of insulating films building up normalized curves are shifted along potential axis. Various structure changes result in qualitative change of curves shape.

On basis of analysis of literature data as well as of own experimental results we suggest some regularity for degradation of silicon electrodes upon cycling. It was shown that an electrode capacity Q at n-th cycle can be calculated from equation Q = Q0 exp(kn+βn 2 /2), where Q0 is initial capacity value, k и β are empiric constants.

Concerning performance, safety, reliability and durability issues, the membrane-electrode assembly (MEA) is probably the weakest cell component. Most performance losses and most accidents occurring during PEM water electrolysis are usually due to the MEA. The purpose of this article is to report on specific degradation mechanisms of the MEA and electrolyser in whole.

Degradation of Na₂Ti₃O₇-based electrodes is studied by galvanostatic as well as electrochemical impedance spectroscopy methods. The rate of degradation was shown to decrease from cycle to cycle as the cycling progresses and also as the cycling current increases. It was concluded that the main reason of degradation is the gradual an electrolyte reduction with the formation of insoluble products (SEI).