【摘要】：鋰離子電池作為一種可充電二次電池具有高能量密度、長壽命和安全等優(yōu)點,已成為便攜式電子產品中主要電源設備。近幾年來,鈉離子電池由于其原料豐富、價格低廉等優(yōu)勢成為全球能源研究領域的熱點,并且在大型儲能設備如智能電網和電動汽車中有良好的應用前景。電極材料作為鈉離子電池發(fā)展的關鍵技術已經過大量研究。其中,正極材料主要分為層狀過渡金屬氧化物、聚陰離子型化合物等類型,負極材料主要有碳材料、合金材料和鈦酸鹽等類型。作為正極材料,具有商業(yè)化潛力的層狀過渡金屬氧化物P2-Na_(0.67)[Fe_(0.5)Mn_(0.5)]O_2不僅成本低而且理論容量值很高,但在電化學循環(huán)過程中容量衰減速度過快,循環(huán)穩(wěn)定性差;聚陰離子型化合物NaTi_2(PO_4)_3由于其三維的空間結構具有良好的離子傳輸通道和化學穩(wěn)定性,是一種理想的負極材料,但其過低的電子電導率導致鈉離子在電化學過程中傳輸受阻,嚴重影響電化學性能。為了提高P2-Na_(0.67)[Fe_(0.5)Mn_(0.5)]O_2的循環(huán)穩(wěn)定性和NaTi_2(PO_4)_3的電子電導率,本論文開展了以下的研究工作:(1)利用非電化學活性金屬元素Zn作為摻雜劑,采用固相反應法在P2-Na_(0.67)[Fe_(0.5)Mn_(0.5)]O_2基礎上摻雜少量的Zn,成功制備出P2-Na_(0.67)[Fe_(0.4)Mn_(0.55)Zn_(0.05)]O_2化合物;再在P2-Na_(0.67)[Fe_(0.2)Mn_(0.65)Ni_(0.15)]O_2基礎上用少量的Zn分別替換Fe或Mn金屬元素,采用固相反應法合成出系列化合物:P2-Na_(0.67)[Fe_(0.2)Mn_(0.65)Ni_(0.1)Zn_(0.05)]O_2、P2-Na_(0.67)[Fe_(0.1)Mn_(0.7)Ni_(0.15)Zn_(0.05)]O_2和P2-Na_(0.67)[Fe_(0.1)Mn_(0.7)Ni_(0.1)Zn_(0.1)]O_2。通過XRD、SEM的方法對合成產物進行材料表征,并分別將材料組裝成半電池后進行電化學性能測試。摻雜后的P2-Na_(0.67)[Fe_(0.5)Mn_(0.5)]O_2循環(huán)穩(wěn)定性改變不大,但P2-Na_(0.67)[Fe_(0.2)Mn_(0.65)Ni_(0.15)]O_2經過摻雜后循環(huán)穩(wěn)定性得到一定的提高。(2)采用化學自組裝法,利用交聯劑PEI進行NaTi_2(PO_4)_3前驅體氨基化,并與氧化石墨烯(GO)在低溫下進行肽鍵反應,最后熱處理得到NaTi_2(PO_4)_3-rGO的復合材料。通過XRD、SEM的方法對合成產物進行材料表征,并組裝成半在電池進行電化學性能測試。未包覆石墨烯的NaTi_2(PO_4)_3起始容量小且迅速衰減,包覆石墨烯后NaTi_2(PO_4)_3在1C倍率下有良好的循環(huán)穩(wěn)定性能。
[Abstract]:As a rechargeable secondary battery with high energy density, long life and safety, Li-ion battery has become the main power supply equipment in portable electronic products. In recent years, sodium ion batteries have become a hot spot in the field of global energy research because of their abundant raw materials and low price, and have a good application prospect in large energy storage equipment such as smart grid and electric vehicles. Electrode materials as a key technology for the development of sodium ion batteries have been extensively studied. Among them, the cathode materials are mainly classified into layered transition metal oxides, polyanionic compounds and other types, while the negative electrode materials are mainly carbon materials, alloy materials and titanate. As cathode materials, the layered transition metal oxide P2-Na0.67 [Fe0.5 Mn0.5] O2 with commercial potential is not only low cost but also has high theoretical capacity, but the capacity decay rate is too fast and the cycle stability is poor during electrochemical cycling. Polyanionic compound NaTi_2 (PO_4) 3 is an ideal negative electrode material because of its good spatial structure of ion transport channel and chemical stability, but its low electronic conductivity leads to the blocking of sodium ion transport in the electrochemical process. The electrochemical performance is seriously affected. In order to improve the cyclic stability of P2-Na _ (0.67) [Fe _ (0.5) mn _ (0.5)] O _ 2 and the electronic conductivity of NaTi_2 (PO_4) _ 3, the following researches have been carried out: (1) the non-electrochemical active metal element Zn is used as dopant. 閲囩敤鍥虹浉鍙嶅簲娉曞湪P2-Na_(0.67)[Fe_(0.5)Mn_(0.5)]O_2鍩虹涓婃幒鏉傚皯閲忕殑Zn,鎴愬姛鍒跺鍑篜2-Na_(0.67)[Fe_(0.4)Mn_(0.55)Zn_(0.05)]O_2鍖栧悎鐗，

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