No abstract

Mechanochemical synthesis of Cu3P in the presence of n‐dodecane results in a material with a secondary particle size distribution of 10 μm, secondary particles which consist of homogeneously agglomerated 20 nm primary particles. The electrochemical performance of Cu3P with lithium is influenced by the reaction depth, in other words by the lower potential cut‐off. During the electrochemical reaction, the displacement of copper by lithium from the Cu3P structure until the formation of Li3P and Cu deteriorates the capacity retention. Improved performance was obtained when the charge potential was limited to 0.50 V (vs. Li/Li+) and the formation of the LixCu3‐xP phase (0 ≤ × ≤ 2). In this case, when the potential is limited to 0.5 V, the capacity is stable for more than 50 cycles. Acceptable electrochemical performances in Li‐ion cells within the voltage range 0.50–2.0 V (vs. Li/Li+) were shown when Cu3P was used as an anode and Li1.2(Ni0.13Mn0.54Co0.13)O2 and LiNi0.5Mn1.5O4 as positive electrode materials.

LiM0.5Mn1.5normalO4 ( M=Fe , Co, Ni) normal spinel oxides were prepared by a citric acid assisted Pechini synthesis with different thermal treatments and compared with respect to their electrochemical performance as cathodes in lithium-ion batteries. Characterization methods include X-ray diffraction, neutron diffraction, inductively coupled plasma optical emission spectroscopy analysis, and scanning electron microscopy. While LiM0.5Mn1.5normalO4 samples crystallize for M=Fe and Co with the 3d cation-disordered cubic spinel-like structure ( Fd3m space group), the 600°C annealed LiNi0.5Mn1.5normalO4 shows a partially ordered structure (belonging to the P4332 space group). The absolute discharge capacity is slightly higher for the Ni-doped samples in comparison with the Co- and Fe-doped spinels. 1000°C annealed samples show an improved cyclability in comparison with the 600°C annealed samples. At elevated temperatures, Co- and Fe-doped samples show much faster degradation in comparison with the Ni-doped sample. The responsible mechanisms are discussed.