3D lithium ion batteries—from fundamentals to fabrication

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

Nanostructured Conductive Polymers for Advanced Energy Storage

Conductive polymers combine the attractive properties associated with conventional polymers and unique electronic properties of metals or semiconductors. Recently, nanostructured conductive polymers have aroused considerable research interest owing to their unique properties over their bulk counterparts, such as large surface areas and shortened pathways for charge/mass transport, which make them promising candidates for broad applications in energy conversion and storage, sensors, actuators, and biomedical devices. Numerous synthetic strategies have been developed to obtain various conductive polymer nanostructures, and high-performance devices based on these nanostructured conductive polymers have been realized. This Tutorial review describes the synthesis and characteristics of different conductive polymer nanostructures; presents the representative applications of nanostructured conductive polymers as active electrode materials for electrochemical capacitors and lithium-ion batteries and new perspectives of functional materials for next-generation high-energy batteries, meanwhile discusses the general design rules, advantages, and limitations of nanostructured conductive polymers in the energy storage field; and provides new insights into future directions.University of Texas at Austin3M Non-tenured Faculty awardWelch Foundation F-1861Materials Science and Engineerin

Electrochemical lithium intercalation in nanosized manganese oxides

X-ray amorphous manganese oxides were prepared by reduction of sodium permanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition of manganese carbonate at moderate temperature (MnOx-C). TEM showed that these materials are not amorphous, but nanostructured, with a prominent spinel substructure in MnOx-C. These materials intercalate lithium with capacities up to 200 mAh/g at first cycle (potential window 1.8-4.3 V) and 175 mAh/g at 100th cycle. Best performances for MnOx-C are obtained with cobalt doping. Potential electrochemical spectroscopy shows that the initial discharge induces a 2-phase transformation in MnOx-C phases, but not in MnOx-I ones. EXAFS and XANES confirm the participation of manganese in the redox process, with variations in local structure much smaller than in known long-range crystallized manganese oxides. X-ray absorption spectroscopy also shows that cobalt in MnOx-C is divalent and does not participate in the electrochemical reaction

MnO2-coated Ni nanorods: Enhanced high rate behavior in pseudo-capacitive supercapacitor

Ni nanorods prepared by electrochemical growth through an anodized aluminium oxide membrane were used as substrate for the electrodeposition of MnO2 either in potentiostatic mode or by a pulsed method. Electrochemical deposition parameters were chosen for an homogeneous deposit onto Ni nanorods. Resulting Ni supportedMnO2 electrodes were tested for electrochemical performances as nanostructured negative electrodes for supercapacitors. They exhibited initial capacitances up to 190 F/g and remarkable performances at high charge/discharge rates

Electrospun nanofibers of manganese oxides with mixed phase for supercapacitor

Energy EngineeringElectrospinning technique produces continuous fibers of various structures and composition with diameters ranging from a few micrometers to nanometers. Particularly, the three-dimensional (3D) non-woven fiber matrix contains a large porous network structure which is highly suitable for electrode applications that can facilitate the access of electrolytes into the active species. For that, we have fabricated the inorganic manganese oxide (MnOx) nanofibers (NFs) of varying composition by electrospinning technique for supercapacitor applications. MnOx is promising for pseudocapacitor due to their fine specific capacitance, low cost, and environmental benignity. In this study, we prepared the electrospun NFs of Mn(OAc)2/poly(vinyl pyrrolidone) (PVP) composite by using electrospinning technique. The as-prepared inorganic NFs were annealed at different temperatures to remove the polymer matrix and resulted in the MnOx NFs of varying composition. Interestingly, we found that the capacitance of MnOx NFs annealed at 500 oC is highest among all samples with contained a mixed phase of Mn2O3 and Mn3O4.ope