In this work, toward uniform in situ carbon coating on nano-LiFePO₄ (nano-LFP) via a solid-state reaction, we systematically investigated the effects of the heating rate on the characteristics of the product and process with nano-FePO₄ as the template and iron source. It was found that the high reactivity of nano-FePO₄ almost eliminated the effect of the heating rate on the phase transformation of LiFePO₄ (LFP) but aggravated the impacts on the morphology and the distribution of the carbon layer of the final product. The uniform carbon coating on nano-LFP was found to correspond to a moderate diffusion rate of gas molecules containing carbon, as determined by the thermal decomposition characteristics of the carbon source and the heating rate together. This strategy showed promise in the accelerated synthesis of nano-LFP/carbon composites with high electrochemical performance and was verified to be effective when using different carbon sources, sucrose and polyvinyl alcohol, which had distinct differences in thermal decomposition characteristics. As a result, we achieved the preparation of nano-LFP with an excellent rate performance (140 mA·h·g^–1@10 C) using a high heating rate (15 °C/min), low calcination temperature (650 °C), and short calcination time (4 h).

中文翻译：

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通过固态反应实现纳米LiFePO ₄上均匀的原位碳涂层

在这项工作中，为了通过固相反应在纳米LiFePO ₄（nano-LFP）上进行均匀的原位碳涂层，我们系统地研究了升温速率对纳米FePO ₄作为产物和工艺特性的影响。模板和铁源。发现纳米FePO ₄的高反应性几乎消除了加热速率对LiFePO ₄相变的影响。（LFP），但加剧了对最终产品的形态和碳层分布的影响。发现纳米LFP上均匀的碳涂层对应于含碳气体分子的适度扩散速率，这取决于碳源的热分解特性和加热速率。该策略在加速合成具有高电化学性能的纳米LFP /碳复合材料方面显示出了希望，并且在使用不同的碳源，蔗糖和聚乙烯醇（在热分解特性方面存在明显差异）时被证明是有效的。结果，我们实现了具有出色的倍率性能（140 mA·h·g ^–1的纳米LFP的制备）@ 10 C）使用高加热速率（15°C / min），较低的煅烧温度（650°C）和较短的煅烧时间（4 h）。