利用表面改性制备磷酸锰锂/石墨烯锂离子电池复合材料（英文）

Li Mn PO4/graphene nanocomposites with high electrochemical performance for lithium-ion batteries

3-氨丙基三甲氧硅烷(APS)改性的磷酸锰锂纳米片与氧化石墨烯通过静电自组装,经喷雾干燥和高温煅烧,得到磷酸锰锂/石墨烯复合材料。APS修饰后的磷酸锰锂带正电荷,并可通过红外光谱中3-氨丙基和SiO C官能团的存在证明磷酸锰锂成功被APS修饰,使得其与带负电荷的氧化石墨烯自组装形成磷酸锰锂/石墨烯复合材料。测试结果表明约25 nm的磷酸锰锂纳米颗粒均匀负载在石墨烯表面,石墨烯片层充当导电网络,提高了材料的电子电导率和锂离子扩散速率,缓解了Li MnPO_4在充放电过程中的体积变化。电性能测试发现,该材料的首次放电比容量为142.2 m A·h·g-1,50个循环后容量保持率达到90.5%,较未经APS修饰的磷酸锰锂/石墨烯材料有大幅提高。

A high performance Li MnPO4/graphene nanocomposite as cathode material for lithium-ion batteries was prepared via surface modification of 3-aminopropyltrimethoxysilane（APS） on Li MnPO4 nanoparticles and electrostatic self-assembly of positively charged APS-Li MnPO4 nanoparticles and negatively charged graphene oxide. Successful APS modification on Li MnPO4 was demonstrated by the existence of 3-aminopropyl and SiO C groups in FTIR spectra. Li MnPO4 nanoparticles（ca. 25 nm） were found uniformly distributed on the surface of graphene sheets. The intimate contact of Li MnPO4 nanoparticles with graphene conductive network allows achieving fast electron transfer between the active material and charge collector and accommodating volume expansion/contraction of Li MnPO4 nanoparticles during electric discharge/charge process. The nanocomposite cathode material could deliver an initial capacity of 142.2 m A·h·g-1 at 0.05 C and maintain 90.5% capacity after 50 cycles, which were significant better than no APS-modified counterpart.