溶剂热法控制合成规则的LiFePO4颗粒

采用溶剂热法在H2O和异丙醇的混合溶剂中合成橄榄石结构的磷酸铁锂(LiFePO4). 场发射扫描电镜(FESEM)结果表明, LiFePO4产品的形貌与导电添加剂密切相关, 当改变导电添加剂的种类(蔗糖、碳黑和石墨)时, 分别得到了棒状和方块状的LiFePO4颗粒. TEM和选区电子衍射(SAED)的结果表明, 棒状的LiFePO4晶体沿着201]方向取向生长. 取向机理可能在于添加剂对晶体生长的吸附阻止作用. 充放电测试表明, 溶剂热法合成的LiFePO4(添加蔗糖)具有145.2 mAh·g-1的可逆容量和良好的循环保持能力, 且表现出优良的倍率放电性能和高温特性, 其4C放电容量为98.1 mAh·g-1, 保持了0.1C容量的67.6%, 且放电电压平台仍保持在3.12 V(vs Li/Li+).

Controllable Synthesis of Regular LiFePO4 Particles via Solvothermal Reaction

Well-crystallized and regular lithium iron phosphate (LiFePO4) particles were synthesized via solvothermal reaction in H2O-isopropanol mixture solvents. FESEM micrographs indicated that the morphology of as-prepared LiFePO4 was strongly dependent on the conductive additives, i.e. when the additive changed from sucrose, carbon black to graphite, the LiFePO4 morphology changed from rod to square block. TEMand SAED results showed that rod-like LiFePO4 crystal grows along 201] direction preferentially. A rationalmechanismbased on the crystal growth prohibiting effect of additive was proposed. LiFePO4 sample with additive sucrose showed the best charge/discharge performance. It was able to deliver a high reversible capacity of 145.2 mAh·g-1 at 0.1C as well as a favorable capacity retention. Furthermore, it exhibited excellent rate performance and temperature performance. It could deliver 98.1 mAh·g-1 at 4C, about 67.6%of that at 0.1C, and the discharge voltage plateau still remained to be 3.12 V(vs Li/Li+).