LiFePO4具有潛力成為下一代陰極材料，其具有低成本、環境友好性及高熱穩定性之優點，但受限於材料本身之低導電性，因而循環及高速率充放電表現仍舊不佳。本研究利用氮摻雜碳進行LiFePO4之包覆，試圖克服其本身低導電度之缺點。
本研究利用三聚氰胺甲醛樹脂(MFR, Melamine-formaldehyde resin)做為包覆以固態法合成LiFePO4之前驅物再進行熱處理，並利用XRD、SEM、EDS、FTIR及Raman光譜進行分析。由XRD結果顯示，以5毫升三聚氰胺甲醛樹脂條件下包覆之LiFePO4，其結構並無改變，也無不純物之生成。但於更高比例之三聚氰胺甲醛樹脂進行處理則會有不純物產生，主要是因為於高溫下三聚氰胺甲醛樹脂分解產生之氨氣有更高之活性與LiFePO4反應產生Fe2P及Li3PO4。而FTIR分析則確認於表面包覆後樣品內存在含氮的鍵結，且Raman光譜結果中D-band強度隨氮含量增加而上升亦顯示氮摻雜對碳結構之影響。由SEM結果則觀察到隨煅燒時間增加，LiFePO4之顆粒大小變小且其聚集程度亦較低，而EDS則發現隨煅燒時間及增加氮含量損失越大，此亦解釋了顆粒大小變小之結果。
電極製作上之參數亦進行了優化，其以5 毫升三聚氰胺甲醛樹脂、10小時及700 oC條件下處理之LiFePO4可得到最佳之電化學表現，於0.1C充放電速率下，第15圈可逆電容可達133.6 mAh/g，相較於未包覆之LiFePO4僅 77 mAh/g。而過電位之現象亦隨循環圈數之增加而降低，其於第15圈充放電時之過電位為54 mV，相比於LiFePO4未包覆之LiFePO4則為320 mV。
由電化學及材料分析結果顯示經氮摻雜碳包覆後之LiFePO4可改善其充放電效率，其可能為氮元素存在於碳之結構中，造成結構空穴及電子空乏，因而降低其鋰離子穿過碳層之能障所造成。

LiFePO4 have potential to be next generation cathode materials. However, despite the low cost, environmental benign and high thermal stability, this material suffers from low conductivity resulting in poor cycling performance and rate capabilities. This work dedicated to adopt nitrogen-doped carbon coating into LiFePO4 systems to overcome the poor conductivity.
Melamine-formaldehyde resin adopted as a nitrogen-doped carbon precursor to coat solid-state LiFePO4 and the resulting products after heat treatment were characterized by XRD, SEM, EDS, FTIR and Raman spectroscopy. XRD show no structural change or impurity formation for the case of 5 mL-MFR treatment but not in the higher amount. The evolution of ammonia at higher temperature makes LiFePO4 more reactive and therefore the impurity of Fe2P and Li3PO4 were formed. The FTIR results confirm the presence of nitrogen in the sample after coating, so do the results from Raman which shows the increase of D-band as the effect of nitrogen in the carbon structure. The morphology of the samples observed by SEM shows the smaller particle size and less agglomeration as the sintering time prolonged. The EDS chemical analysis also shows that the loss of nitrogen increase in longer sintering time, which result in smaller particle size.
The coating process has been systematically optimized. The highest performance of coated LiFePO4 was achieved under 5 mL-MFR treatments on LiFePO4 followed by 10 hours sintering at 700 °C. It was found that the reversible capacity of 133.6 mAh/g was obtained in comparison with 77 mAh/g of the bare one at the 15th cycle (0.1 C discharge rates). The observed overpotential decrease with the increase of cycle number, the coated sample shows only 54 mV overpotential compared 320 mV to bare one at 15th cycle.
The electrochemical and material analysis suggests that rate capability of LiFePO4 was improved with the incorporated nitrogen in the carbon structure. The presence of vacancy and electron deficiency came from incorporated nitrogen site lowers the energy barrier of the Li-ion passing through the carbon network.

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