AsianScientist (Sep. 29, 2015) – Are your batteries running out too quickly? If so, you might be interested to know that researchers in China have developed a material that could make lithium (Li) batteries better: graphdiyne (GDY). Their work has been published in Nano Energy.
In the pursuit of higher capacity, rate capability and longer cycling life for Li storage materials, many different carbon structures have been studied. They include fullerenes, carbon nanotubes (CNTs) and graphene, which have zero-, one-, and two-dimensional (2D) architectures, respectively. The carbon atoms in these structures are all sp2-hybridized, the same as those in graphite.
Although the Li capacity can be improved greatly upon applying these different morphologies, the nature of the Li-intercalated layer does not change much among these sp2-hybridized, hexagonal carbon structures. This limits the room for further improvement in capacity.
GDY is a new carbon allotrope that was synthesized relatively recently. It comprises sp- and sp2-hybridized carbon atoms and has been predicted to be the most stable of the various diacetylenic non-natural carbon allotropes. Density functional theory and first-principles calculations have indicated that the maximum Li storage capacity of monolayer GDY can be as high as 744 mAh/g (LiC3), which is twice that of the commercial graphite (372 mAh/g, LiC6).
A team from Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) and Institute of Chemistry (ICCAS), led by Professors Huang Changshui and Li Yuliang, showed that Li-ion batteries featuring GDY-based electrode exhibited excellent electrochemical performance, including high specific capacities, outstanding rate performances, and a long cycle lives.
This superior performance was explained by the unique structure of GDY, with a large number of triangular pores, each accommodating three Li atoms located at three asymmetric sites. The increased number of Li storage sites facilitied Li ion adsorption, desorption and diffusion both in-plane and out-plane.
A capacity of up to 520 mAh/g after 400 cycles at a current density of 500 mA/g could be obtained using pure GDY. At an even higher current density of 2 A/g, cells incorporating GDY-based electrodes retained a high specific capacity of 420 mAh/g after 1,000 cycles. Its considerably high mobility and high Li storage capacity make GDY a promising candidate material employed in rechargeable Li-ion-based energy storage devices.
The researchers expect that designing and preparing novel carbon-based materials with large pores will open up new approaches for the development of Li storage materials exhibiting high capacities and excellent cycling stabilities, thereby satisfying the future requirements of next-generation Li storage batteries.
The article can be found at: Huang et al. (2015) Graphdiyne for High Capacity and Long-Life Lithium Storage.
———
Source: Chinese Academy of Sciences.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
