Micro-ionics: next generation power sources

Abstract

The desire for ever smarter systems-on-a-chip and plug-free portable electronics with longer operating times between recharge has stimulated growing interest in micro-ionic systems. The use of thin film and photolithographic processing techniques, commonly at temperatures considerably below those utilized in conventional ceramics processing methods, leads to ionic or mixed ionic-electronic materials with nanosized dimensions. The implications for nanosized grains on the conductivity of thin film solid oxide electrolytes are examined. Grain boundary engineering, as a means of controlling and ultimately enhancing transport along and across grain boundaries, becomes essential given that such boundaries often dominate the transport properties of such nano-dimensioned materials. Heterogeneous doping by selective in-diffusion along grain boundaries was introduced as a potentially powerful means of achieving this. This is coupled with the modeling of space charge distributions at such boundaries, taking into account possible dopant segregation to the boundaries. The use of lithographic methods for generating geometrically well defined structures is used to illustrate how one can achieve a much improved understanding of electrode processes in SOFC structures. Indeed, the more idealized structures achievable by application of microelectronic processing provide a marvelous opportunity to uncover the science underlying the technology of micro- and ultimately macro-ionics.

Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO2—case study

“…Following an annealing treatment at 800°C for 40 h (Fig. 1, red pattern), one notices a slight shift of the peak position vs. higher Bragg angles, indicating a decrease of the unit cell parameter; as the sample was treated at high pO 2 at the end of the experiment, this is consistent with a slightly higher oxygen deficiency of the as-received nanopowder. The average crystallite size after the experiment was (40±10) nm.…”

“…The intriguing properties of nanocrystalline metal oxides are generally associated with their high surface to volume ratio and high interface density [1][2][3]. Excellent performance has been reported in various energy storage and conversion applications: to give just a few examples, nanostructured oxide electrodes enable reduction of the operating temperature in solid oxide fuel cells [4]; significantly higher insertion capacity and better cycling have been demonstrated for nanostructured oxide electrodes in lithium-ion batteries [5,6]; nanostructured electrodes improve the performance of dyesensitized solar cells by several orders of magnitude compared to bulk electrodes [7,8].…”

Caracterización eléctrica de fronteras de grano en conductores iónicos mediante medidas de espectroscopia de impedancias en un bicristal

“…En los últimos años, debido a la posibilidad de acceder con mayor facilidad a la escala nanométrica, existe un elevado interés por estudiar este tipo de efectos de tamaño sobre las propiedades físicas de los materiales. En particular, en el área de los materiales conductores iónicos, la investigación en este tipo de efectos ha dado lugar a un nuevo campo científico que se ha dado en denominar "nanoiónicos" (1)(2)(3)(4). Al disminuir el tamaño de grano en muestras nanocristalinas, o el espesor en películas ultradelgadas, aumenta drásticamente el número y volumen relativo de las fronteras de grano o interfases del material, y por tanto la influencia de éstas sobre las propiedades físicas del sistema.…”

Surface Chemistry and Non-Stoichiometry of Nd2NiO4+ δ Epitaxial Thin Films with Different Orientation and Strain

“…Understanding the fundamental aspects of fast oxygen transport and electro-catalytic activity at moderate temperatures in oxides is a key for designing high performance electrodes in solid oxide fuel cells (SOFCs), gas sensors, and separation membranes (1)(2)(3)(4)(5). Particularly important is the ability to tune at the atomic-level structural, chemical, and electronic properties of the oxide surfaces and interfaces (6).…”