The composite material makes the ultrafast lithium ion capacitors - Dr. Huiyang Gou

APRIL 14, 2017

The rapidly growing energy demand requires the development of advanced electrical energy storage technology. New work from co-led by Dr. Huiyang Gou of HPSTAR, Dr. Gongkai Wang from Hebei University of Technology and Prof. Jie Lian from RPI published in Nano Energy show that the composite materials of nanosized Li4Ti5O12 (LTO) and graphene nanosheets can have excellent reversible capacity, rate capability, and cyclic stability as anode materials for lithium ion capacitors.

The composite material showed the great performance for lithium ion capacitors, the reversible capacity of 120.8 mA h g−1 at an extremely high current rate of 100 C was achieved successfully, and the electrode can be charged/discharged to about 70% of the theoretical capacity of LTO in 25s. Meanwhile, the composite exhibited excellent cyclic stability of 90% capacity retention at 20 C with nearly 100% Coulombic efficiency after 2500 cycles.

“We introduced ALD technique, for the first time, for the realization of high performance composites of nanosized LTO and graphene nanosheets as anode materials for LICs. TiO2 nanoislands were seeded on graphene by ALD process in advance, ensuring the unique structure formation of subsequent LTO”, as the leading author of Dr. Gongkai Wang said.

The sintering treatment, the crystallinity, defect density, microstructure and electrochemical property of the composite have significant effects on its electrochemical performance, Huiyang said, this is also supported by theoretical calculations.

The results provides a foundation for a feasible design to incorporate energy storage materials onto conductive host materials, propelling the forefront and shedding new light of electrical energy storage devices with high power/energy densities.

Caption:  A novel atomic layer deposition seeded Li4Ti5O12/graphene anode for ultrafast lithium ion capacitors.

世界对能源及其新技术的需求持续增长, 也对储能器件提出了更高的要求. 锂离子混合超级电容器是一种基于锂离子电池和超级电容器双重储能机制的储能器件, 由于具备高的能量密度和功率密度, 长寿命以及高安全性, 有望应用于纯电动和混合动力汽车领域. 本研究首次利用原子层沉积育种技术制备钛酸锂/石墨烯复合电极材料，并利用第一性原理从理论上进行了计算分析。该材料独特的微观结构使其充电25秒即可实现70%的理论容量（即100 C电流密度时的放电容量高达120.8 mAh/g）。此项技术为制备新型石墨烯复合电极材料开辟了新思路，以该复合材料为负极的锂离子混合电容器的功率密度甚至超越了双电层型超级电容器，具有重要的研究意义和实际应用价值。

原文链接：http://www.sciencedirect.com/science/article/pii/S2211285517302227