Key Laboratory of Polar Materials and Devices (MOE) and Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Department of Electronic Engineering, East China Normal University, Shanghai 200241, China.
Nanoscale. 2018 Feb 8;10(6):2944-2954. doi: 10.1039/c7nr08191j.
Boosting the lifespan of MnO-based materials for future lithium ion batteries is one of the primary challenges due to the intrinsic low ionic conductivity and volume expansion during the conversion process. Herein, superior lithium storage in a new quaternary MnO-Cu-CNT/graphene composite has been demonstrated, which is boosted by pseudocapacitance benefitting from the three-dimensional CNT/graphene and nanosized Cu additives. Such architecture offers highly interpenetrated porous conductive networks in intimate contact with MnO-Cu grains and abundant stress buffer space for effective charge transport upon cycling. The ternary MnO-Cu-graphene electrode contributes an ever-increasing reversible capacity of 938.3 mA h g after 800 cycles at 0.8 A g. In particular, the quaternary MnO-Cu-CNT/graphene electrode demonstrates a high specific capacity of 1334 mA h g at 0.8 A g after 800 cycles and long lifetimes of more than 3500 cycles at 5 A g with a capacity of 557.9 mA h g and close-to-100% Coulombic efficiency. The boosted pseudocapacitive lithium storage together with the simple material fabrication method in a MnO-Cu-CNT/graphene hybrid could pave the way for the development of high-capacity and long-life energy storage devices.
提高基于 MnO 的材料在未来锂离子电池中的寿命是主要挑战之一，这是由于其在转化过程中固有的低离子导电性和体积膨胀。本文展示了一种新的四元 MnO-Cu-CNT/石墨烯复合材料在锂离子存储方面的卓越性能，得益于三维 CNT/石墨烯和纳米 Cu 添加剂的赝电容，其锂离子存储性能得到了提升。这种结构提供了高度相互渗透的多孔导电网络，与 MnO-Cu 颗粒紧密接触，并在循环过程中提供了丰富的应力缓冲空间，有利于有效电荷传输。三元 MnO-Cu-石墨烯电极在 0.8 A g 的电流密度下循环 800 次后，可逆容量不断增加，达到 938.3 mA h g。特别是，四元 MnO-Cu-CNT/石墨烯电极在 0.8 A g 的电流密度下循环 800 次后具有 1334 mA h g 的高比容量，在 5 A g 的电流密度下循环 3500 次以上后具有超过 557.9 mA h g 的容量和接近 100%的库仑效率，具有长寿命。这种提升的赝电容锂离子存储性能，以及在 MnO-Cu-CNT/石墨烯杂化中使用的简单材料制备方法，为开发高容量和长寿命储能器件铺平了道路。
