本文選題：富鋰錳基材料 + 離子取代�。� 參考：《上海應(yīng)用技術(shù)大學(xué)》2017年碩士論文

【摘要】：為改善富鋰錳基材料充放電過程中首周不可逆容量高、循環(huán)穩(wěn)定性和倍率性能較差等缺陷,本文依次引入Al3+和Rb+少量替代過渡金屬層離子和鋰層離子,并結(jié)合其形貌、結(jié)構(gòu)及電化學(xué)性能具體分析了材料的最佳配比。采用噴霧干燥輔助固相合成技術(shù)制得材料Li1.2Mn0.54-xAlxNi0.13Co0.13O2(LMO-Alx,x=0、0.03、0.05、0.10、0.15)。研究發(fā)現(xiàn),LMO-Alo.05材料的電化學(xué)性能最佳,0.2C充放電過程中材料的放電比容量最高可達(dá)249.9 mAh g-1,50圈循環(huán)后保持率為99.2%。這首先歸因于LMO-Al0.05材料電導(dǎo)率的提高(3.87×10-8Scm-1),相較于LMO材料的電導(dǎo)率僅2.52×10-8Scm-1。此外,A13+的引入增大了材料晶胞體積,使得鋰離子擴(kuò)散系數(shù)從4.18×10-13cm2 s-1 (LMO)提高至 1.22×10-12cm2s-1 (LMO-Al005)。通過碳酸鹽共沉淀法合成了材料Li1.2-xRbxMn0.54Ni0.13Co0.13O2 (Rbx-LMO,x=0、0.01、0.03、0.05)。結(jié)果表明,x=0.03時(shí),Rb0.03-LMO材料經(jīng)0.2C充放電100圈后容量由239 mAh g-1衰減至221.9 mAh g-1,保持率為92.8%,相比于LMO材料容量保持率僅82.9%。此外,倍率性能方面,Rb0.03-LMO材料也顯示出較為優(yōu)異的快速充放電能力,0.05C～5C各倍率放電容量均比LMO材料高出20～30%。這是因?yàn)?引入半徑較大的Rb+拓寬了晶胞的鋰層層間距,鋰離子擴(kuò)散系數(shù)由8.95×10-16cm2s-1(LMO)增至1.63×10-15cm2 s-1(Rb0.03-LMO);其次,鍵能更強(qiáng)的Rb-O鍵可抑制高壓過程氧的釋放,為脫鋰態(tài)的富鋰錳基材料提供結(jié)構(gòu)支撐,緩解充放電過程中材料結(jié)構(gòu)的轉(zhuǎn)變,改善材料的結(jié)構(gòu)穩(wěn)定性,進(jìn)而提高其電化學(xué)性能。
[Abstract]:In order to improve the defects such as high first cycle irreversible capacity, poor cyclic stability and poor rate performance during charge and discharge of Li-rich manganese based materials, a small amount of Al3 and RB were introduced to replace transition metal layer ions and lithium layer ions, and their morphology was combined. The structure and electrochemical properties of the materials were analyzed in detail. The material Li1.2Mn0.54-xAlxNi0.13Co0.13O2 LMO-AlxUXO2LMO-AlxCXO0O0. 03N0. 03N0. 05A0. 10N0. 15m was prepared by spray drying assisted solid state synthesis technique. It is found that the electrochemical performance of LMO-Alo.05 is the best. The discharge specific capacity of LMO-Alo.05 can reach 249.9 mAh g ~ (-1) ~ (50) cycle and the retention rate is 99.2 during the charge-discharge process. This is attributed to the increase of electrical conductivity of LMO-Al0.05 material (3.87 脳 10-8 Scm-1), which is only 2.52 脳 10-8 Scm-1 compared with that of LMO material. In addition, the introduction of A13 increases the unit cell volume and increases the diffusion coefficient of lithium ion from 4.18 脳 10-13cm2 s-1 to 1.22 脳 10-12cm2s-1 / LMO-Al005. The material Li1.2-xRbxMn0.54Ni0.13Co0.13O2 Rbx-LMOX (0. 01%) was synthesized by carbonate coprecipitation method. The results show that the capacity of Rb0.03-LMO material decreases from 239 mAh g ~ (-1) to 221.9 mAh g ~ (-1) from 221.9 mAh g ~ (-1) to 221.9 mAh g ~ (-1) after 0.2C charge-discharge at 0.03, and the retention rate is 92.8%, compared with that of LMO material, the capacity retention rate is only 82.9%. In addition, the Rb0.03-LMO material also shows excellent rapid charge and discharge capacity of 0.05Cn5C, and the discharge capacity of Rb0.03-LMO material is 20% higher than that of LMO material. This is because the introduction of RB with a larger radius widens the interlayer spacing of lithium, and the diffusion coefficient of lithium ion increases from 8.95 脳 10 ~ (-16) cm ~ (-2) to 1.63 脳 10-15cm2 ~ (-1) Rb 0.03-LMOO _ 3. Secondly, the release of oxygen during high pressure can be inhibited by Rb-O bond with stronger bond energy. It provides structural support for lithium-rich manganese based materials in delithium-state, alleviates the structural transformation of materials during charge and discharge, improves the structural stability of materials, and then improves their electrochemical properties.
【學(xué)位授予單位】：上海應(yīng)用技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912;TB34

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