双碳涂层LiMnPO_4/C的制备及其电化学性能的研究

Synthesis and electrochemical performance of LiMnPO_4/C coated by duble carbon

以碳酸锂、草酸锰和磷酸二氢铵为原料、抗坏血酸为还原剂和碳源、PEG400为分散剂,采用二次球磨混料二次煅烧并相结合的方法合成双碳涂层包覆纳米级磷酸锰锂,并用XRD、SEM和恒电流充放电技术研究了一次煅烧温度和时间、二次煅烧温度和时间对材料结构形态和电化学性能的影响。结果表明,在550℃煅烧3 h,650℃煅烧10 h的条件下所合成的LiMnPO4为橄榄石结构的纯相材料;材料晶粒的尺寸可达到几十纳米;在0.1 C下首次充电容量为110 m A·h/g,放电容量为87 m A·h/g,首次充放电效率为79%,经过50次循环后,放电容量保持率约为98%,具有一定的循环稳定性。

A LiMnPO4 powder was synthesized using lithium carbonate, manganese oxalate and am-monium dihydrogen phosphate as raw material, the L-ascorbic acid as the reducing agent and the carbon source, and PEG400 as a dispersant. The lithium manganese phosphate were synthesized by a double ball-milled with a double heated method. The effects of different first sintering temperature and time, and different second sintering temperature and time on the morphology and electrochemi-cal properties of the products were characterized by X-ray diffraction （ XRD） , scanning electron mi-croscopy （ SEM） and constant current charge and discharge technology. The results showed that the LiMnPO4 obtained at the conditions of 550 ℃ calcined for 3 h and 650 ℃ calcined for 10 h was of pure phase and olivine structure. The material particle size can reach several tens of nanometers. The products exhibited the initial charge capacity of 110 mA ＆#183; h/g, the discharge capacity of 87 mA＆#183;h/g and the first efficiency was 79% at 0. 1C. After 50 cycles, the discharge capacity re-tention rate remained 98%, with a certain cycle stability.