Low dimensional nanomaterials for energy storage applications

13 Jan 2016 EPD Energy

Yang Hui Ying

One of the greatest challenges besetting the development of Lithium (Li) ion battery technologies these days is the difficulty of fast charging.  

It is even more difficult to maintain a high energy density battery within a flexible and compact design. An energy dense battery within a small, confined space runs a higher risk of explosion due to volumetric expansions within the anode material, which is traditionally graphite. However, given the strong demand for electric vehicles and wearable electronics, it is crucial that we surmount this challenge.

In a recent work, a SUTD research team lead by Associate Professor Yang Hui Ying and Research Scientist Dr Mo Runwei have designed an innovative nanoscale architecture comprising of a nitrogen-doped graphene shell covering high capacity germanium quantum dots (Ge-QDs) on a nitrogen-doped graphene scaffold. Such “yolk-shell” architecture can provide void space for the volumetric expansion of Ge-QDs as Li ions move in and out of the QDs. The design of flexible batteries are based on the graphene scaffold, which provides a structured porosity that enables ease of electrolyte access and maintains a high electrical conductivity throughout the Ge-QD matrix.

Based on these unique properties, an extremely high performance flexible battery has been designed and developed. The specific reversible capacity is more than 1,220 mAh g-1 (4 times higher than commercial batteries) and a fast charging time of 90 seconds was achieved for this new anode material. The team is now moving towards higher energy and power densities and long cycle life time flexible battery system. 

Read more at Nature Communications.