Negative capacitance and instability at electrified
interfaces: Lessons from the study of membrane capacitors
Authors: M.B.Partenskii, P.C.Jordan (Department of Chemistry, MS-015 Brandeis University PO Box 549110 Waltham, MA 02454-9110, USA)
Various models leading to predictions of negative capacitance, C, are briefly reviewed. Their relation to the nature of electric control is discussed. We reconfirm that the calculated double layer capacitance can be negative under σ-control - an artificial construct that requires uniform distribution of the electrode surface charge density, σ. However, only the total charge C (or the average surface charge density ) can be experimentally fixed in isolated cell studies (q-control). For those σ where C becomes negative under σ-control, the transition to q-control (i.e. relaxing the lateral change density distribution, fixing its mean value to σ) leads to instability of the uniform distribution and a transition to a non-uniform phase. As an illustration, a “membrane capacitor” model is discussed. This exactly solvable model, allowing for both uniform and inhomogeneous relaxation of the electrical double layer, helps to demonstrate both the onset and some important features of the instability. Possibilities for further development are discussed briefly.
electrochemical interfaces, instabilities and phase transitions,
electric double layers, capacitance, membrane electroporation
PACS: 68.35.Rh, 68.35.Md, 82.45.Mp, 82.45.Rr, 82.45.Uv, 68.08.-p, 73.30.+y
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