Laboratory Scale Production of Lithium Manganese Oxide as Active Material of Lithum-Ion Batteries in Sol-Gel Method Assisted by Local Biomass

Experimental and theoretical studies of the production of lithium manganese oxide (LiMn2O4) using sol-gel method have been carried out on a larger scale than previous studies. The purpose of this investigation was to observe sample behavior along the synthesis process to be considered in further scale-up production of lithium manganese oxide, based on the sol-gel method. Calcination products were analyzed by TGA and crystalline phase formation analyzed by XRD. LiMn2O4 spinel phase was formed at 600oC. SEM showed some interesting morphology. Xerogel swelling was observed overwhelmingly during drying at 250oC to 300oC. Exothermic occurrence as a source of irregular and unpredictable auto combustion in the calcination process. Both phenomenon were not observed in a xerogel made with a small amount precursor. Therefore, initial mixture adjustment and additional steps were considered for production.

Correlative Confocal Raman and Scanning Probe Microscopy in the Ionically Active Particles of LiMn2O4 Cathodes

In this contribution, a correlative confocal Raman and scanning probe microscopy approach was implemented to find a relation between the composition, lithiation state, and functional electrochemical response in individual micro-scale particles of a LiMn2O4 spinel in a commercial Li battery cathode. Electrochemical strain microscopy (ESM) was implemented both at a low-frequency (3.5 kHz) and in a high-frequency range of excitation (above 400 kHz). It was shown that the high-frequency ESM has a significant cross-talk with topography due to a tip-sample electrostatic interaction, while the low-frequency ESM yields a response correlated with distributions of Li ions and electrochemically inactive phases revealed by the confocal Raman microscopy. Parasitic contributions into the electromechanical response from the local Joule heating and flexoelectric effect were considered as well and found to be negligible. It was concluded that the low-frequency ESM response directly corresponds to the confocal Raman microscopy data. The analysis implemented in this work is an important step towards the quantitative measurement of diffusion coefficients and ion concentration via strain-based scanning probe microscopy methods in a wide range of ionically active materials.

Effects of Sodium Substitution on the Rate Performances of Spherical LiMn2O4 Cathode for Lithium Ion Batteries

Sodium substitution Li1-xNaxMn2O4 cathodes were synthesized by a solid-state reaction method. The morphologies and crystal structures of Li1-xNaxMn2O4 were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. All Li1-xNaxMn2O4 samples exhibited a single phase LiMn2O4 spinel structure with good crystallinity. The effect of Na+ ions on the electrochemical performance of Li1-xNaxMn2O4 was investigated by galvanostatic charge-discharge test. The results showed that lithium substituted by sodium deteriorated its capacity retention but enhance its discharge capacity when it worked at large current densities. The initial discharge capacity was 114.2 mAh/g for Li0.94Na0.06Mn2O4, and 93.1 mAh/g remained after 300 cycles at a current density of 2220 mA/g in the voltage range 3.0–4.3 V at room temperature.