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Zr-modified LiNi1/3Co1/3Mn1/3− xZr xO2 samples were prepared through a rheological-phase method. The results indicate that there is only partial Zr doping into the bulk phase of the LiNi1/3Co1/3Mn1/3O2 particles, whereas the rest of the Zr remained on the surface to form a Li2ZrO3 coating layer during the Zr-modification process. The Zr-modified LiNi1/3Co1/3Mn1/3− xZr xO2 samples show lower discharge specific capacities at low rates, however, which exhibit clearly improved rate capabilities than that of pristine LiNi1/3Co1/3Mn1/3O2. Among the Zr-modified LiNi1/3Co1/3Mn1/3− xZr xO2 samples, LiNi1/3Co1/3Mn1/3−0.01Zr0.01O2 ( x=0.01) shows the best rate capability, which exhibts158, 142, and 132 mAh g−1 at 1.0, 2.0, and 3.0 C, respectively. The related results indicate that the doped Zr in pristine LiNi1/3Co1/3Mn1/3O2 could improve the structure stability and the formation of an inactive Li2ZrO3 coating layer which could suppress the interfacial side reaction of LiNi1/3Co1/3Mn1/3O2. [ABSTRACT FROM AUTHOR]

The commercial Li 4 Ti 5 O 12 (LTO) is successfully modified by SrF 2 via a low temperature coprecipitation process. The results indicate that Sr 2+ and F − do not co-dope into the bulk phase of the LTO, but instead form a SrF 2 coating layer on the surface of the LTO. The suitable SrF 2 buffer layer could cover the catalytic active sites of the LTO and suppress the electrolyte reduction decomposition on the surface of the LTO, which means that the SrF 2 modification is favorable to suppress gas generation of the LIBs using LTO as anode material during charge/discharge cycles and storage. Moreover, according to optimized the amount of SrF 2 , the 2 wt% of SrF 2 in the SrF 2 modified LTO composites exhibits the best rate capability and an excellent cyclic performance. [ABSTRACT FROM AUTHOR]

Abstract: The influences of LiBF4, LiClO4, lithium bis(oxalato) borate (LiBOB), LiPF6 with VC and without VC, and the mixed electrolytes composed of different ratios of LiBOB and LiPF6 or LiClO4 on the electrochemical properties of Si/graphite/disordered carbon (Si/G/DC) composite electrode were systematically investigated by constant current charge–discharge and electrochemical impedance spectra (EIS) techniques. Scanning electron microscopy (SEM) was used to observe the change of electrodes in morphology after given cycle numbers. X-ray photoelectron spectroscopy (XPS) was employed to understand the influences of different mixed electrolytes on the composition of SEI layers. The results showed that Si/G/DC composite electrode in the mixed electrolytes presented better electrochemical performance than in single electrolyte. The compactness and compositions of SEI layers intensively influenced the cycle performance of Si/G/DC composite materials. LiBOB and additive VC had a good synergistic effect on the formation of the dense SEI layers. In particular, Si/G/DC in 0.5M LiBOB+0.38M LiPF6 electrolytes containing VC exhibited a high reversible capacity and excellent cycle performance. [Copyright &y& Elsevier]