Papers by Keyword: Cycleability

Abstract: A LiNi_0.4Co_0.2Mn_0.4O₂ material was prepared via the co-precipitation in solution and ensuing solid reaction of the prepared precursors with LiOH.H₂O, investigating the influence of solid reaction temperature on the cation mixing and electrochemical performance of the materials as a cathode. The results show that Li⁺/Ni²⁺ cation mixing decreases with the increase of calcination temperature in the range of 700-900°C, and the lower degree of cation mixing can improve 2D layered structure and make the material more stable. The discharge capacity and the capacity retention rate of the material is strongly impacted by the reaction temperature.The powders calcined at 900°C show the best electrochemical performance and the initial discharge capacity is 163.1mA·h/g, after 40 cycles, the capacity retention rate is 93.9%.

Abstract: A spinel-structured LiNi_0.5-xCr_2xMn_1.5-xO₄(x=0, 0.05) were prepared via co-precipitation routes. The experiment results from XRD, SEM and electrochemical analyses show that the substitutions of Ni and Cr for Mn in LiMn₂O₄can not prevent Mn²⁺from being oxidized into Mn³⁺ in solution process, however,Mn²⁺ oxidation does not change their final crystal structures of spinel phase, but do influence the Li/Ni²⁺ cation mixing and Mn³⁺occurrence in lattice. After substitution the first charge and discharge capacities decrease but its cycleability is improved significantly, especially for the Ni and Cr co-substitution

Abstract: LiNi_0.8Co_0.15Al_0.05O₂, as the cathode materials for lithium ion battery, were prepared from the precursors, Ni_0.8Co_0.15Al_0.05(OH)₂ which were synthesized by chemical co-precipitation method. LiNi_0.8Co_0.15Al_0.05O₂ particles are modified with AlF₃ and AlPO₄. Even though the initial discharge capacity of the coated LiNi_0.8Co_0.15Al_0.05O₂ was decreased that of the pristine material, the capacity retention and the thermal stability, in a highly oxidized state are both significantly improved. This effect is attributed to the thin coating layer protecting the oxidized cathode particles from being attacked by hydrogen fluoride in the electrolyte. The cycling behavior of the AlF₃-coated LiNi_0.8Co_0.15Al_0.05O₂ is quite stable showing good capacity retention (96.3% of its initial capacity after 30 cycles).

Abstract: Li_1+xMn_2-x-yAl_yO₄cathode materials were prepared via co-precipitation route; and the crystalline structures, morphologies and electrochemical performance of the prepared powder samples are characterized by XRD, SEM, Galvanostatic charge–discharge cycling. Experimental results show that Li, Al co-substitution significantly enforces the crystalline structures and improves the cycle stability of LiMn₂O₄ materials, and Li_1.1Mn_1.805Al_0.095O₄ exhibits promising electrochemical performance.

Abstract: Recently, combination of ductile carbonaceous materials with the metallic Sn has received a great deal of interest to be a novel anode material for lithium ion batteries, because of their higher capacity than the conventional graphite anodes and better cycleability than the pure Sn anodes. Electrochemical performance of the Sn/C composite anodes is influenced by the material system, particle size and size distribution of Sn as well as the amount of deposited Sn. This study revealed that a favorable Sn/C composite anode exhibited reduced size and uniformly distributed tin particles. The crystal structure, morphology and elemental distribution were analyzed by XRD patterns, SEM and EPMA, respectively. The carbothermal-reducted Sn/Mesophase graphite powder (MGP) composite anodes exhibited much higher capacity than the bare MGP, and the initial efficiency was also much higher than the metallic tin anode in literatures.