Li₄Ti₅O₁₂/LiMnPO₄ lithium-ion battery systems for load leveling application

A new type of lithium-ion cell based on the combination of spinel Li ₄Ti₅O₁₂ anode with a high voltage olivine LiMnPO₄ cathode, which can be promising for load leveling applications, is demonstrated for the first time. The power and safety characteristics of this battery system were found to meet the requirement for this application. The structure, surface morphology, and the performance were characterized by X-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and standard electrochemical techniques. A stable reversible capacity up to 125 mAh g^-1 of the cathode in full cell could be measured at discharge potentials 2.5 V with a reasonable capacity retention during prolonged charge/discharge cycling. The thermal stability of pristine and electrochemically delithiated LiMnPO₄-Li₄Ti ₅O₁₂ composite cathodes and anodes in contact with the electrolyte solution was investigated by differential scanning calorimetry (DSC). The electrodes were also studied by thermogravimetric analysis, coupled with mass spectrometry. We did not found appreciable changes in the thermal stability of the electrodes in their pristine and charged states, in contact with LiPF₆ solution in mixtures of ethylene carbonate (EC) and dimethyl carbonate (DMC).