427061 A Self-Supported and Long-Life Li-Se Battery Cathode Enabled By 3D Mesoporous Carbon/Graphene Hierarchical Architecture

Tuesday, November 10, 2015: 3:15 PM
251F (Salt Palace Convention Center)
Kai Han, Central South University, Changsha, China

For 2015 AIChE Annual Meeting

Topical 5: Nanomaterials for Energy Applications

Session: Nanomaterials for Energy Storage

A Self-supported and Long-life Li-Se Battery Cathode Enabled by 3D Mesoporous Carbon/Graphene Hierarchical Architecture

Kai, Han*, Central South University (China)      hankai@csu.edu.cn

Heng, Jiang, Central South University (China)      Hongqi, Ye, Central South University (China)

Zhao, Liu, Northwestern University (USA)            Fang Dai, GM, Global R&D (USA)

Lithium-ion batteries have been widely used as one of the most important energy storage techniques in the past decades. However, the energy density of current Li-ion batteries is insufficient to satisfy the requirements for emerging technologies, such as electric vehicles and smart grid, which is mainly limited by the low capacity of cathode materials. Therefore, developing high-capacity cathode materials are urgently needed. Although sulfur could offer high theoretical lithium storage capacity when applied as cathode, the Li-Sulfur batteries significantly suffer from poor cycling stability due to the insulating nature of sulfur and shuttling effect of polysulfides. Most recently, selenium from same group as sulfur has been considered to be a promising alternative for high energy and long cycle life Li batteries due to its comparable volumetric capacity to but much better electrical conductivity than sulfur.  However, Li-Se system also faces two similar issues: shuttling of polyselenides and volume change during charge/discharge processes.

    In this work, we strategically design and fabricate a self-supported selenium composite with a 3D hierarchical architecture constructed by mesoporous carbon and graphene, in which selenium is impregnated into the mesoporous carbon nanoparticles (Se/MCN), followed by further embedding between graphene sheets (Se/MCN-RGO). Structural characterization by XRD and SEM/TEM provide clear evidence for the unique structure. Such architecture not only provides the electrode with excellent electrical and ionic conductivity, but also efficiently suppresses polyselenides shuttling and accommodates volume change during charge-discharge cycling. At selenium content of 62%, the Se/MCN-RGO cathode exhibits not only high discharge capacity of 655 mAh g-1 at 0.1 C (97% of theoretical capacity) but also long cycling stability under high rate (a very small capacity decay of 0.008% per cycle over 1300 cycles at 1C). It is furthermore believed that the concept of such 3D hierarchical carbon architecture could be easily expanded to other advanced energy storage systems, such as silicon for Li-ion batteries and metal oxide for supercapacitors. The structural and electrochemical characterization results of the high-performance Se/MCN-RGO composite will be presented.

Keywords: Long-life Li-Se batteries; selenium cathode; mesoporous carbon; graphene

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