Liping Mao

Oxidative stability and reduction decomposition mechanism studies on a novel salt: lithium difluoro(sulfato)borate

Lithium difluoro(sulfato)borate (LiBF2SO4) is a novel salt designed for battery electrolyte usage. Limited information is currently available, however, regarding its structure and chemical characteristics. The density functional theory calculation has therefore been used to explore both the oxidative stability and the reduction decomposition mechanism of LiBF2SO4. The results show that the oxidation potential (EOX) for LiBF2SO4 could be calculated using the correlation between the highest occupied molecular orbital energy and the corresponding EOX. In addition, the reduction decomposition mechanism of LiBF2SO4, particularly at a high potential of about 1.7 V (vs. Li/Li+) during the first discharge, has been calculated. In addition, many other electrolyte salts have also been investigated, to broaden the current knowledge of the use of chelato-borates as electrolyte components, to design and select high-performance electrolyte salts for lithium ion batteries, and to predict the chemical and physical characteristics of screening electrolyte salts, with the intent of using this induction for up-coming projected studies.

Electrochemical performance of LiNi0.5Mn1.5O4 doped with la and its compatiblity with new electrolyte system

Cathode materials LiNi0.5Mn1.5O4 and LiNi0.5 − x/2LaxMn1.5 − x/2O4 (x = 0.04, 0.1, 0.14) were successfully prepared by the sol-gel self-combustion reaction (SCR) method. The X-ray diffraction (XRD) patterns indicated that, a few of doping La ions did not change the structure of LiNi0.5Mn1.5O4 material. The scanning electronic microscopy (SEM) showed that the sample heated at 800°C for 12 h and then annealed at 600°C for 10 h exhibited excellent geometry appearance. A novel electrolyte system, 0.7 mol L−1 lithium bis(oxalate)borate (LiBOB)-propylene carbonate (PC)/dimethyl carbonate (DMC) (1: 1, v/v), was used in the cycle performance test of the cell. The results showed that the cell with this novel electrolyte system performed better than the one with traditional electrolyte system, 1.0 mol L−1 LiPF6-ethylene carbonate (EC)/DMC (1: 1, v/v). And the electrochemical properties tests showed that LiNi0.45La0.1Mn1.45O4/Li cell performed better than LiNi0.5Mn1.5O4/Li cell at cycle performance, median voltage, and efficiency.

Improved electrochemical properties of nickel rich LiNi0.6Co0.2Mn0.2O2 cathode materials by Al2O3 coating

Al2O3 has successfully coated on LiNi0.6Co0.2Mn0.2O2 cathode material by a facile coating method. The results of scanning electron microscopy and transmission electron microscope images show that Al2O3 were successfully attached onto the surface of LiNi0.6Co0.2Mn0.2O2 as expected. Charge–discharge tests show that the Al2O3 coating LiNi0.6Co0.2Mn0.2O2 exhibits excellent electrochemical performance with a high initial discharge capacity of 180.2 mAh g-1 at 0.1 C and a high capacity retention of 95.2% after 100 cycles at room temperature under 1C. The superior performance of surface-modified LiNi0.6Co0.2Mn0.2O2 attributed to the uniform Al2O3 coating layer is expected to directly reduce the contact between the active cathode particles and electrolyte. Simultaneously, the uniform Al2O3 coating layer also improves structure stability and suppresses generation of oxygen.Al2O3 has successfully coated on LiNi0.6Co0.2Mn0.2O2 cathode material by a facile coating method. The results of scanning electron microscopy and transmission electron microscope images show that Al2O3 were successfully attached onto the surface of LiNi0.6Co0.2Mn0.2O2 as expected. Charge–discharge tests show that the Al2O3 coating LiNi0.6Co0.2Mn0.2O2 exhibits excellent electrochemical performance with a high initial discharge capacity of 180.2 mAh g-1 at 0.1 C and a high capacity retention of 95.2% after 100 cycles at room temperature under 1C. The superior performance of surface-modified LiNi0.6Co0.2Mn0.2O2 attributed to the uniform Al2O3 coating layer is expected to directly reduce the contact between the active cathode particles and electrolyte. Simultaneously, the uniform Al2O3 coating layer also improves structure stability and suppresses generation of oxygen.