高容量的Li1.1Mn2O3.95F0.05锂离子二次电池正极材料

High Capacity Li1.1Mn2O3.95F0.05 Cathode Materials for Li-ion Rechargeable Battery

以无水乙醇为分散剂在行星式球磨机中对原料进行预处理后，经固相反应制备了富锂化合物Li1.1Mn2O3.95·F0.05,并以该化合物作为锂离子二次电池正极材料,进行了电化学测试.结果表明,加氟后的富锂化合物Li1.1Mn2O3.95·F0.05可与LiGoO2相比,可逆容量高达143mA·h/g,且具有良好的循环稳定性,循环115次后,容量保持率在95%以上.SEM和TEM的表征,说明该方法制备的样品颗粒均匀,具有较好的晶体外观.XRD表征,说明该化合物具有完美的尖晶石结构.锂含量的原子吸收光谱(AAS)表征说明该化合物为富锂化合物Li1.1Mn2O3.95F0.05电化学测试结果和SEM,TEM,AAS表征支持掺氟后的富锂化合物Li1.1Mn2O3.95F0.05晶胞内空缺增大,使锂离子的嵌入脱出更加容易,并且使更多的锂离子参与嵌入脱出反应.

The compound, Li1.1Mn2O3.95F0.05 was synthesized by means of solid - state reaction with precursors ball - milled in planetary micro - mill with alcohol as dispersing liquid, and was electrochemically tested as a cathode material for lithium rechargeable battery. The results showed that the performance of the compound was good, which had a surprising reversible capacity, up to 143 mA . h/g, which was almost equivalent to that of LiCoO2. Furthermore, it exhibited satisfactory cyclic stability, with above 95% retainable capacity after cycling 115 times. SEM and TEM showed the sample were uniform particles with good crystal morphology. XRD analysis identified that the compound had a spinel structure of LiMn2O4. Atomic absorption spectroscope (AAS) proved that this compound was Li-rich (Li11Mn2O3.95F0.05)-Mn-.. Electrochemical test results, SEM, TEM, XRD and AAS supported that in Li - rich Li1.1Mn2O3.95F0.05, the added fluorine made the crystal space becoming larger and the intercalation - deintercalation of lithium ions was much easier and more lithium ions were involved into the reaction.