富锂锰基多层氧化物电极材料的制备与改性

Preparation and modification of lithium-rich manganese-based layered oxide cathode materials

富锂多层氧化物(LLOs)因其具有比容量大、能量密度高等优点而有望成为锂电池的电极材料。但该材料在工作条件下生成的尖晶石相会导致容量下降。在LLOs中掺杂Mn的氧化物形成Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54-x)Mn_(x)O_(2)(x=0,0.0025,0.0050,0.0075)可以有效提高其循环性能。实验结果表明:将Mn引入到LLOs的晶格中,使得晶胞参数增大,晶面间距增大,有利于Li+的脱出和嵌入,能够提供更为宽阔的锂离子通道供锂离子快速迁移,有利于电极/电解液界面上的锂离子扩散,并且可以提高锂离子电池的比容量。含有0.5%(质量分数)Mn氧化物的样品100次充放电后容量保持率为94.3%,5 C电流密度下仍具有139.6 mAh/g的放电比容量。

The lithium-rich layered oxides(LLOs)are promising lithium-ion cathode material because of their high specific capacity and energy density.However,the spinel phase formed in the material under working conditions leads to a decrease in reversible capacity.Doping Mn to the LLOs to form Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54-x)Mn_(x)O_(2)(x=0,0.0025,0.0050,0.0075)can efficiently improve the cycling stability.The results show that the introduction of Mn into the lattice of the LLOs makes the cell parameters and the crystal plane spacing increase,which benefits the Li+lithiation/delithiation,can provide a wider lithium ion channel for rapid lithium ion diffusion,benefits the lithium ion diffusion at the interface of electrode/electrolyte,and improves the specific capacity.The capacity retention of the prepared sample containing 0.5%Mn oxide is 94.3%after 100 cycles,and its discharge specific capacity is 139.6 mAh/g at 5 C.