The Ni-rich Li[Ni0.6Co0.2Mn0.2]O2 surface has been modified with H3PO4. After coating at 80 ℃, the products were heated further at a moderate temperature of 500 ℃ in air, when the added H3PO4 transformed to Li3PO4 a...The Ni-rich Li[Ni0.6Co0.2Mn0.2]O2 surface has been modified with H3PO4. After coating at 80 ℃, the products were heated further at a moderate temperature of 500 ℃ in air, when the added H3PO4 transformed to Li3PO4 after reacting with residual LiOH and Li2CO3 on the surface. A thin and uniform smooth nanolayer （〈 10 nm） was observed on the surface of Li[Ni0.6Co0.2Mn0.2]O2 as confirmed by transmission electron microscopy （TEM）. Time-of-flight secondary ion mass spectroscopic （ToF-SIMS） data exhibit the presence of LIP＋, LiPO-, and Li2PO2＋ fragments, indicating the formation of the Li3PO4 coating layer on the surface of the Li[Ni0.6Co0.2Mn0.2]O2. As a result, the amounts of residual lithium compounds, such as LiOH and Li2CO3, are significantly reduced. As a consequence, the LigPO4-coated Li[Ni0.6Co0.2Mn0.2]O2 exhibits noticeable improvement in capacity retention and rate capability due to the reduction of residual LiOH and Li2CO3. Further investigation of the extensively cycled electrodes by X-ray diffraction （XRD）, TEM, and ToF-SIMS demonstrated that the LiBPO4 coating layers have multi-functions： Absorption of water in the electrolyte that lowers the HF level, HF scavenging, and protection of the active materials from deleterious side reactions with the electrolyte during extensive cycling, enabling high capacity retention over 1,000 cycles.展开更多
文摘The Ni-rich Li[Ni0.6Co0.2Mn0.2]O2 surface has been modified with H3PO4. After coating at 80 ℃, the products were heated further at a moderate temperature of 500 ℃ in air, when the added H3PO4 transformed to Li3PO4 after reacting with residual LiOH and Li2CO3 on the surface. A thin and uniform smooth nanolayer （〈 10 nm） was observed on the surface of Li[Ni0.6Co0.2Mn0.2]O2 as confirmed by transmission electron microscopy （TEM）. Time-of-flight secondary ion mass spectroscopic （ToF-SIMS） data exhibit the presence of LIP＋, LiPO-, and Li2PO2＋ fragments, indicating the formation of the Li3PO4 coating layer on the surface of the Li[Ni0.6Co0.2Mn0.2]O2. As a result, the amounts of residual lithium compounds, such as LiOH and Li2CO3, are significantly reduced. As a consequence, the LigPO4-coated Li[Ni0.6Co0.2Mn0.2]O2 exhibits noticeable improvement in capacity retention and rate capability due to the reduction of residual LiOH and Li2CO3. Further investigation of the extensively cycled electrodes by X-ray diffraction （XRD）, TEM, and ToF-SIMS demonstrated that the LiBPO4 coating layers have multi-functions： Absorption of water in the electrolyte that lowers the HF level, HF scavenging, and protection of the active materials from deleterious side reactions with the electrolyte during extensive cycling, enabling high capacity retention over 1,000 cycles.
文摘为了制备锂离子电池正极材料球形LiFePO4,以曲拉通-100(Tx-100)作表面活性剂,用超声波法制备了LiFePO4的前驱体材料μm级球形Li3PO4粉末,并用X射线衍射进行了表征.研究了各种因素对Li3PO4颗粒形态的影响,得到了超声波法制备球形Li3PO4粉末的适宜条件:反应温度为35℃,Li+的浓度为0.6 mol/L,Tx-100的质量百分数为10%,超声波作用时间为5 min.
