In order to improve the charge/discharge cycling performance of the LiMn2O4 cathode, the spinel LiMn2O4 is coated on the structurally stable SiO2 nanosphere cores, LiMn2O4@SiO2. The core-shell LiMn2O4@SiO2 nanosphere cathodes are prepared by the MnCO3 precipitation on the silica surface and the following solid state reaction of MnCO3@SiO2 with a lithium salt. The charge/discharge cycle stability has improved by the nanostructural characteristics of the LiMn2O4@ shell on the SiO2 core. The cathode composed of LiMn2O4@SiO2 nanospheres exhibits higher capacity retention of 97% than that of LiMn2O4 nanoparticles of 89%, after 100 battery cycles at a 10C rate.

We show in a theoretical density functional theory study that amorphous Si (a-Si) has more favorable energetics for Mg storage compared to crystalline Si (c-Si). Specifically, Mg and Li insertion is compared in a model a-Si simulation cell. Multiple sites for Mg insertion with a wide range of binding energies are identified. For many sites, Mg defect formation energies are negative, whereas they are positive in c-Si. Moreover, while clustering in c-Si destabilizes the insertion sites (by about 0.1/0.2 eV per atom for nearest-neighbor Li/Mg), it is found to stabilize some of the insertion sites for both Li (by up to 0.27 eV) and Mg (by up to 0.35 eV) in a-Si. This could have significant implications on the performance of Si anodes in Mg batteries.

Silicon is a very promising material for anodes of lithium ion batteries. It exhibits a high theoretical capacity of 3579 mAh/g. However, during the lithiation and de-lithiation, silicon materials experience up to a 300% volume change, leading to poor cyclability [1-2]. Research shows that reducing the silicon particle size can mitigate this problem. Carbon nanotubes (CNTs) function well as electrode materials in electrolytic cells because of their high electrical conductivity and surface area. In this work, we combine silicon nanoparticles (Si NPs) and CNTs as anode materials. Si NPs are generated using a plasma-enhanced chemical vapor deposition technique and their surface is modified with a 12-carbon long aliphatic chain to impart solubility in non-polar solvents. They are applied onto a nanotube-based layer using a wet-phase deposition technique. SEM and TEM analysis confirm that they form a conformal coating onto the nanotube surface. The CNTs - Si NPs composite active material is tested in half-cells where lithium foil acts as counter electrode. We have achieved an average of 810 mAh/g discharge capacity for composites with a CNTs to Si NPs weight ratio of 1:1. We expect to be able to increase the discharge capacity by increasing the Si NPs weight content.

With the advent of printed electronics and flexible devices, flexible energy storage has received so much attention in the past few years. In this work, a scalable process for manufacturing of a flexible supercapacitor device based on nanostructured PANI and MnO2 was demonstrated. In this process, nanostructured materials are transformed into form of a printable ink which is applied on a current collector using a simple screen printing method, which can be used in a roll to roll scheme. The flexible device was assembled using a solid polymer electrolyte and the electrochemical performance of the devices was evaluated. A specific capacitance of 120 F/g and 89 F/g for two symmetrical devices based on PANI and MnO2 were obtained respectively. The devices are showing relatively good cyclability and columbic efficiency.

We present neutron diffraction results on superionic materials that are good candidates for use as solid-state electrolytes in next generation Li+ ion batteries. Lithium ion conducting glasses of the compositions xLi2SO4-(1-x) [0.5Li2O-0.5(2NH4H2PO2)] ; x=0 and 0.1 were synthesized by conventional melt-quenching. The transparent homogeneous glassy flakes were thus obtained and used for the characterization. The materials are glassy in nature and composed of a complex network of the following sub-units: Li2O, Li2SO4, and 2NH4H2PO2. This disordered structure is integral to its function in that it promotes Li+ ion conduction while suppressing electronic conduction, the necessary qualities of a good Li+ electrolyte. We used neutron diffraction to study the formation of crystallites upon heating of the material above 400°C. The crystallite formation is understood to be detrimental to the Li+ ion mobility and, hence, is identified with a diminished performance in devices that require heating in their fabrication processs. Here, we report the changes in the material, as observed by neutron diffraction, as a function of annealing temperature and temperature history.

An efficient microwave-assisted polyol (MP) approach is report to prepare SnO2/graphene hybrid as an anode material for lithium ion batteries. The key factor to this MP method is to start with uniform graphene oxide (GO) suspension, in which a large amount of surface oxygenate groups ensures homogeneous distribution of the SnO2 nanoparticles onto the GO sheets under the microwave irradiation. The period for the microwave heating only takes 10 min. The obtained SnO2/graphene hybrid anode possesses a reversible capacity of 967 mAh g-1 at 0.1 C and a high Coulombic efficiency of 80.5% at the first cycle. The cycling performance and the rate capability of the hybrid anode are enhanced in comparison with that of the bare graphene anode. This improvement of electrochemical performance can be attributed to the formation of a 3-dimensional framework. Accordingly, this study provides an economical MP route for the fabrication of SnO2/graphene hybrid as an anode material for high-performance Li-ion batteries.