(中南大學(xué) 冶金科學(xué)與工程學(xué)院， 長沙 410083)
摘 要: 采用高溫固相法合成了鋰離子電池正極材料LiFePO4及改性的LiFe0.9Ni0.1PO4和LiFe0.9Ni0.1PO4/C材料。 采用X射線衍射儀和掃描電鏡分析樣品的晶體結(jié)構(gòu)和表面形貌。 結(jié)果表明： 改性后的LiFe0.9Ni0.1PO4和LiFe0.9Ni0.1PO4/C材料與LiFePO4一樣均為單一的橄欖石結(jié)構(gòu)。 以20 mA/g電流密度充放電， LiFe0.9Ni0.1PO4的首次放電容量為140 mA·h/g， 較LiFePO4增加了12%； 而復(fù)合摻雜得到的含碳量為2.8％的LiFe0.9Ni0.1PO4/C材料， 首次放電容量達(dá)162 mA·h/g， 充放電循環(huán)30次后放電電容量仍為147 mA·h/g， 容量衰減僅為9％。 當(dāng)充放電電流密度提高到80 mA/g時， LiFePO4、 LiFe0.9Ni0.1PO4和LiFe0.9Ni0.1PO4/C的放電容量分別為86、 114和140 mA·h/g。 改性后的LiFe0.9Ni0.1PO4/C的電化學(xué)性能得到了較大的改善。
關(guān)鍵字: LiFePO4； Ni摻雜； 碳包覆； 電化學(xué)性能
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract: LiFePO4, LiFe0.9Ni0.1PO4 and LiFe0.9Ni0.1PO4/C were synthesized by solid-state reaction and all samples were characterized by XRD, SEM and electrochemical performance. The results show that LiFe0.9Ni0.1PO4 and LiFe0.9Ni0.1PO4/C are still olivine type with good electrochemical performance. When the cathode materials are cycled at 20 mA/g, the LiFe0.9Ni0.1PO4 can delivered 140 mA·h/g at the first discharge which is 12% higher than that of LiFePO4, while LiFe0.9Ni0.1PO4/C can reach 162 mA·h/g at the first discharge and only lost about 9% after 30 cycles. When the discharge current density reaches up to 80 mA/g, the capacity of LiFePO4, LiFe0.9Ni0.1PO4 and LiFe0.9Ni0.1PO4/C are 86, 114 and 140 mA·h/g, respectively.
Key words: LiFePO4; Ni doping; carbon coating; electrochemical performance
