Recent studies show that the SEI on lithium and on LixC6 anodes in liquid nonaqueous solutions consists of many different materials including Li2O , LiF, LiCl, Li2CO3,LiCO2‐R , alkoxides, and nonconducting polymers. The equivalent circuit for such a mosaic‐type SEI electrode is extremely complex. It is shown that near room temperature the grain‐boundary resistance (R gb) for polyparticle solid electrolytes is larger than the bulk ionic resistance. Up to now, all models of SEI electrodes ignored the contribution of R gb to the overall SEI resistance. We show here that this neglect has no justification. On the basis of recent results, we propose here for SEI electrodes equivalent circuits which take into account the contribution of grain‐boundary and other interfacial impedance terms. This model accounts for a variety of different types of Nyquist plots reported for lithium and LixC6 electrodes in liquid nonaqueous and polymer electrolytes.

3D microbatteries are proposed as a step change in the energy and power per footprint of surface mountable rechargeable batteries for microelectromechanical systems (MEMS) and other small electronic devices. Within a battery electrode, a 3D nanoarchitecture gives mesoporosity, increasing power by reducing the length of the diffusion path; in the separator region it can form the basis of a robust but porous solid, isolating the electrodes and immobilising an otherwise fluid electrolyte. 3D microarchitecture of the whole cell allows fabrication of interdigitated or interpenetrating networks that minimise the ionic path length between the electrodes in a thick cell. This article outlines the design principles for 3D microbatteries and estimates the geometrical and physical requirements of the materials. It then gives selected examples of recent progress in the techniques available for fabrication of 3D battery structures by successive deposition of electrodes, electrolytes and current collectors onto microstructured substrates by self-assembly methods.

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This contribution presents an overview of more than three-decades-long studies of the structure and mechanism of ion conduction in polyethylene-oxide-based solid polymer electrolytes. Conductivity in polymer electrolytes has long been viewed as confined to the amorphous phase above the glass-transition temperature (Tg). Above Tg, polymer chain motion creates a dynamic, disordered environment that was thought to play a critical role in facilitating ion transport. Difficulty of finding the amorphous polymer with sufficient ionic conductivity has raised the fundamental question of whether polymer electrolytes are intrinsically inferior to other electrolytes in terms of their charge-transport capability. Recently, enhanced ionic conductivity has been detected in ordered (longitudinally stretched and cast under gradient magnetic field) polymer electrolytes, in crystalline ion-polyether 1:6 complexes and polymer-in-salt electrolytes. These results have opened a new trend in the search for ion transport in solid polymer electrolytes. The very latest publications present new hybrid-and block-co-polymers, a new class of functional materials (polymerized ionic liquids), and new promising approaches aimed at the development of polymer-based superionic conductors with rigid nanochannel architectures that enable rapid ion transport decoupled from segmental relaxation. Solid Polymer Electrolytes-Structure and Mechanism of Ion TransportMuch research deals with high-ionic-conductive polymer electrolytes because of their current and potential applications as electrochromic and temperature-sensitive printed electronics devices, biomedical sensors, supercapacitors, solar cells and batteries. Polymer electrolytes offer pronounced advantages over conventional liquid electrolytes. These include: a versatile shape, mechanical strength and stable contact between the electrode and electrolyte interfaces. In addition, solid electrolytes are safer than liquid electrolytes as they do not have a leakage problem and because of their nontoxic, low-vaporpressure, and non-flammable properties. [1][2][3][4][5][6][7] Ion-polyether complexes (or polymer electrolytes) were first discovered by Fenton, Parker and Wright in 1973. 8 Since then, such complexes have been prepared with many different monatomic ions and indeed many different polymeric ligands. Armand in 1979 recognized that Li + -polyether complexes could be used as solid electrolytes in electrochemical devices. 9The classic polymer electrolyte comprises organic macromolecules (usually polyether polymer) that are complexed with inorganic salts. The polymer matrix must contain a Lewis base (e.g. ethylene-oxide unit, -OCH 2 CH 2 -) to solvate the lithium salt. The salt-solvent mixing entropy consists mainly of two components: translational and configurational. Contrary to the case of water, the mixing entropy for the formation of polymer electrolytes is small or even positive. The incorporation of salts into the polymer inevitably reduces the freedom of polymer-chain motion, thus causing ...

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