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Cobalt-free, nickel-rich positive electrode materials are attracting attention because of their high energy density and low cost, and the ultimate material is LiNiO

Co-free Ni-rich (Ni ≥ 80 at%) layered positive electrode materials have been attracting attention for lithium-ion batteries with high energy density and low cost. In this study, LiNixAl1−xO2 (x = 0.92, 0.95), in which Ni and Al are atomically mixed, was synthesized. LiNiO2, LiNi0.95Co0.05O2 and LiNi0.95Co0.03Al0.02O2 with similar particle morphologies were also synthesized to clarify the effects of Al and Co substitution in Ni-rich layered electrode materials. After 500 cycles in full cells under conditions of 45 °C, 2C, and 2.5–4.2 V, LiNi0.95Al0.05O2 and LiNi0.95Co0.05O2 showed a similar capacity retention (54.1%, 56.5%), whereas LiNi0.92Al0.08O2 showed excellent capacity retention (75%). The increase of charge transfer resistance with cycling was remarkably suppressed in LiNixAl1−xO2, compared to LiNiO2 and LiNi0.95Co0.05O2, owing to nano-scale Al-rich layers on the surface of LiNixAl1−xO2 suppressing the side reactions with the electrolytes and thus the surface degradation. Furthermore, though the Co substitution has some effects of preventing particle cracking, the least particle cracking was observed in LiNi0.92Al0.08O2, suggesting that the surface degradation and the bulk degradation were suppressed with the Al substitution to produce the excellent cycle performance. This indicates that LiNixAl1−xO2 synthesized under optimum conditions is a promising Co-free Ni-rich electrode material.

Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone–tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone–tissue bonding, such as chemical treatment with H 2 O 2 or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H 2 O 2 chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO 2 (anatase phase) layers as UV was irradiated under a few different conditions. TiO 2 layer was prepared by the chemical treatment with H 2 O 2 solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 °C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.