研究了用于锂电池的潜在 4 V 正极材料。橄榄石型 Li(Mn y 2+ Fe 1-y 2+ )PO 4 (放电状态)及其脱锂形式(Mn y 3+ Fe 1-y 3+ )PO 4 (充电状态)的晶体化学使用 X 射线衍射、穆斯堡尔光谱和 ab initio 计算进行了比较研究。使用强氧化剂四氟硼酸硝鎓NO 2 BF 4 对Li(Mn y 2+ Fe 1-y 2+ )PO 4 进行化学脱锂,得到(Mn y 3+ Fe 1-y 3+ )PO 4 。由 (Mn y 3+ Fe 1-y 3+ )PO 4 (带电状态)中的三价锰 (3d 4 ) 引起的强电子/晶格相互作用被强调为产生完整理论容量(约 170 mAh/g) 的富锰相 (y > 0.8),然后是优化的 Li(Mn 0.6 Fe 0.4 )PO 4 的高效阴极性能。
significantly altered the electrochemicalproperties of the olivine cathode: large specific capacity (> 140 mAh/g) and small capacity fading. Although the importance of carbon deposition was confirmed as reported elsewhere, the structuralmodification effect was also more important than the surface one. The result will contribute to reduce carbon content of LiFePO4 -based positive electrodes, which is important
Mechanoactivation-assisted synthesis and electrochemical characterization of manganese lightly doped LiFePO4
作者:Yuefang Wang、Di Zhang、Xing Yu、Rui Cai、Zongping Shao、Xiao-Zhen Liao、Zi-Feng Ma
DOI:10.1016/j.jallcom.2009.12.014
日期:2010.3
LiFe 0.8 Mn 0.2 PO 4 is electrochemically utilizable correspondingly. For a comparison, they are only 65% and 15% for the pristine LiFePO4 prepared by a similar process. LiFe 1− x Mn x PO 4 also showed stable cycling performance within the 50 cycles under test. It suggests manganese lightly doped LiFePO4 could be practical cathodematerials for high-ratelithium-ionbatteries.
摘要 通过机械活化辅助的固态反应合成了锂离子二次电池正极用橄榄石化合物 LiFe 1− x Mn x PO 4 (0.0 ≤ x ≤ 0.3)。通过XRD、EDX图谱、循环伏安法和充放电表征研究了合成粉末的最佳锰含量和电化学性能。根据 XRD 和 EDX 映射结果,在氮气氛下在 700 °C 下煅烧 20 小时后,形成了具有橄榄石结构的纯相化合物。在被测的各种 LiFe 1- x Mn x PO 4 中,LiFe 0.8 Mn 0.2 PO 4 表现出最高的电导率,室温下达到 3.49 × 10 -5 S cm -1 ,比其高 5 个数量级以上。原始 LiFePO 4 (1.08 × 10 -10 S cm -1 ) 没有碳涂层,原始的 LiFe 0.8 Mn 0. 2 PO 4 在0.1和1 C倍率下的放电容量分别为~123和100 mAh g -1 。这意味着 LiFe 0.8 Mn 0
Different electrochemical responses of LiFe0.5Mn0.5PO4 prepared by mechanochemical and solvothermal methods
作者:Nina V. Kosova、Olga A. Podgornova、Anton K. Gutakovskii
DOI:10.1016/j.jallcom.2018.01.242
日期:2018.4
sloping voltage plateau at 3.4 V. Its post-coating with carbon at 750 °C leads to the appearance of two commonly observed plateaus, corresponding to the Fe2+/Fe3+ and Mn2+/Mn3+ redox couples, and improves cyclability and rate capability. Carbon-coated LFMP-SS consists of irregular-shaped submicron particles and demonstrates two two-phase plateaus and an additional one at 3.6–3.7 V upon discharge. According
摘要 对机械化学辅助固态合成(SS) 和溶剂热合成(ST) 制备的LiFe0.5Mn0.5PO4 (LFMP) 的晶体结构、形貌和电化学进行了比较研究。制备的样品通过 XRD、FTIR、拉曼、Mӧssbauer、SEM、TEM、恒电流循环、GITT 和 EIS 进行了研究。低温无碳 LFMP-ST 在 b 方向上显示出 20-30 nm 厚度的纳米片,与 LFMP-SS 相比,其特征在于低浓度的 MLi 缺陷和更扭曲的 MO6 八面体。它显示出较差的导电性,并且只有一个 3.4 V 的倾斜电压平台。 它在 750 °C 下用碳进行后涂层导致出现两个常见的平台,对应于 Fe2+/Fe3+ 和 Mn2+/Mn3+ 氧化还原对,并提高可循环性和倍率能力。碳涂层 LFMP-SS 由不规则形状的亚微米颗粒组成,并在放电时显示出两个两相平台和一个额外的 3.6-3.7 V 平台。根据 GITT 研究,
High Throughput Electrochemical Observation of Structural Phase Changes in LiFe[sub 1−x]Mn[sub x]PO[sub 4] during Charge and Discharge
作者:Matthew R. Roberts、Girts Vitins、Guy Denuault、John R. Owen
DOI:10.1149/1.3294564
日期:——
Electrochemical lithium extraction and insertion in LiFe1-xMnxPO4 has been investigated by high throughput cyclic voltammetry on an array of samples with different degrees of carbon coating to assist electron transfer. A linear decrease in the capacity was observed with an increase in the value of x and was explained by a gradual loss of electronic conductivity due to the manganese substituent. Slow
已经通过高通量循环伏安法对一系列具有不同程度碳涂层以辅助电子转移的样品研究了 LiFe1-xMnxPO4 中的电化学锂提取和嵌入。随着 x 值的增加,观察到容量的线性下降,这可以用由于锰取代基导致的电子导电性逐渐丧失来解释。慢扫描伏安图显示了对应于 LiFePO4 中的异相(两相)反应和 LiFe0.2Mn0.8PO4 中铁的均相(单相)反应的峰形差异,说明了对伏安图的一般解释以区分这些机制。