The tungsten-doped (0.5 and 1.0 mol%) LiNi0.88Co0.09Al0.03O2(NCA) cathode materials are manufactured to systematically examine the stabilizing effect of W-doping. The 1.0 mol% W-doped LiNi0.88Co0.09Al0.03O2(W1.0-NCA) cathodes deliver 173.5 mAh g−1even after 100 cycles at 1 C, which is 95.2% of the initial capacity. While the capacity retention of NCA cathodes cycled in identical conditions is 86.3%. The optimal performances of the W1.0-NCA could be ascribed to the suppression of impendence increase and the decrease in anisotropic volume change, as well as preventing the collapse of structures during cycling. These findings demonstrate that the W-doping considerably enhances the electrochemical performance of NCA, which has potential applications in the development of Ni-rich layered cathode materials that can display high capacity with superior cycling stability.Keywords:tungsten doping;phase transition;structural stability;electrochemical performance;LiNi0.88Co0.09Al0.03O2
Wei Huang,Weidong Zhuang,Ning Li,Min Gao,Wenjin Li,Xianran Xing,Shigang Lu
LiNi 0.88 Co 0.09 Al 0.03 O 2 is one of the most promising and practical candidates to be applied as next-generation cathodes for lithium-ion batteries due to its high discharge specific capacity (approximately 210 mAh g −1 ), energy density and low cost. Nevertheless, severe capacity fading and poor rate performance are the major barriers for their large-scale application. Herein, a simple and sufficient mechanical mixing method is adopted to prepare a nanoscale Y-doped ZrO 2 modified LiNi 0.88 Co 0.09 Al 0.03 O 2 cathode material with enhanced electrochemical performance . The crystal structures, surface morphologies and electrochemical properties of the bare and modified materials are also characterized. The results confirm that the as-prepared Y-doped ZrO 2 modified LiNi 0.88 Co 0.09 Al 0.03 O 2 cathode material delivers an initial discharge specific capacity of 215.1 mAh g −1 with a coulombic efficiency of 91.8% between 2.5 and 4.3 V. The cycling stability is also remarkably enhanced with a capacity retention from 67.5% to 85.5% after 100 cycles at 1 C rate. Further investigations indicate that the aforementioned excellent performance can be attributed to suppressing impedance increase by stabilizing the cathode material from unfavorable side reactions with the electrolyte and preventing the propagation of intergranular cracking without hindering lithium-ion diffusion .
Nickel–Cobalt–Aluminum (NCA) cathode materials for lithium-ion batteries (LIBs) are conventionally synthesized by chemical co-precipitation. However, the co-precipitation of Ni2+, Co2+, and Al3+ is difficult to control because the three ions have different solubility product constants. This study proposes a new synthetic route of NCA, which allows fabrication of fine and well-constructed NCA cathode materials by a high temperature solid-state reaction assisted by a fast solvothermal process. The capacity of the LiNi0.88Co0.09Al0.03O2 as-synthesized by the solvothermal method was 154.6 mA h g−1 at 55 °C after 100 cycles, corresponding to 75.93% retention. In comparison, NCA prepared by the co-precipitation method delivered only 130.3 mA h g−1 after 100 cycles, with a retention of 63.31%. Therefore, the fast solvothermal process-assisted high temperature solid-state method is a promising candidate for synthesizing high-performance NCA cathode materials.
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