組成、 結(jié)構(gòu)與表征
(中南大學(xué) 冶金科學(xué)與工程學(xué)院， 長沙 410083)
摘 要: 以MnO2和LiOH·H2O為原料， 采用機械活化與濕化學(xué)集成的方法，在水溶液中直接合成了結(jié)晶態(tài)的尖晶石鋰錳氧化物。 當(dāng)鋰含量介于3.78%~4.35%之間時，所得鋰錳氧化物為納米級球形粉末， 以尖晶石結(jié)構(gòu)為主， 含極少量的Mn3O4雜相；在300~800℃溫度范圍內(nèi)熱處理后， Mn3O4雜相消失，尖晶石結(jié)構(gòu)更趨完善。 所合成的含鋰5.80%的高鋰樣品則以LiMnO2層狀結(jié)構(gòu)為主，含少量Mn3O4雜相，其SEM形貌為片狀；在300~700℃下熱處理8h后， 層狀LiMnO2轉(zhuǎn)變成尖晶石LiMn2O4， Mn3O4雜相峰明顯減弱并隨熱處理溫度的升高而消失；當(dāng)溫度升高至700~800℃時，開始出現(xiàn)缺鋰的Li1-xMn2O4相。結(jié)果表明： 該法制備鋰錳氧化物可實現(xiàn)鋰、 錳、 氧在原子級水平的均勻混合， 所得產(chǎn)物的熱穩(wěn)定性能良好， 其化學(xué)計量組成與結(jié)構(gòu)易于調(diào)整和控制。
關(guān)鍵字: 尖晶石鋰錳氧化物； 機械活化； 濕化學(xué)； 合成； 表征
SUN Pei-mei,HUO Guang-sheng, SUN Zhao-ming
（College of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:A crystal spinel LiMn2O4 was directly synthesized by using MnO2 and LiOH·H2O as raw materials in aqueous solution by the process of wet-chemistry integrated with mechanically activation. The synthesized Li-Mn-O compound with Li content between 3.78%-4.35% is a nano-powerder with mainly spinel structure of LiMn2O4 besides a little impurity Mn3O4 and similar spherical morphology. After being heat treated at 300-800℃ for 8h, a single spinel LiMn2O4 with perfect structure was obtained with the disappearing of Mn3O4 phase. The sample with Li content of 5.80% has a mainly layered structure of LiMnO2 besides some Mn3O4 and lamellar morphology. The layered LiMnO2 can be transformed completely into spinel LiMn2O4 after being heat treated at 300-700℃ and the Mn3O4 phase decreased gradually and disappeared at last, but a little Li1-xMn2O4 was formed above 700℃. The results show that Li, Mn and O can be mixed in atomic level to form spinel LiMn2O4 in the present process. The products synthesized with Li less than 4.35% have a good thermal stability and the chemical composition and phase structure can be easily adjusted and controlled.
Key words: lithium manganese oxide spinel; mechanical activation; wet chemistry; synthesis; characterization
