The Next generation supercapacitor’s research and its application on public transit

Dianbo Ruan

Ningbo CRRC New Energy Technology Co., LTD.

Abstract:

1. Instruction and Experimental

   Supercapacitors (SCs), also known as ultracapacitor, play an increasingly important role in public transit application owing to their high power density and long cycling life. With the advanced functional materials and engineering technologies, recently, supercapacitors’ energy density has moved from 5Wh/kg to 11Wh/kg (Carbon based), and it can fully satisfied the energy demands for tramcar or short-term trolleybus. However, in order to improve the working distance and low down the power cost, higher safety and excellent electrochemical performance supercapacitor have also been another huge market for public transit application.

 In order to combine the high energy density performance from Lithium ion battery and excellent power density properties from supercapacitors, two type of hybrid capacitors with LiMn2O4/AC as positive and Li4Ti5O12/AC as negative materials for one kind, and activated carbon as positive and Li4Ti5O12 as negative materials were prepared. The new system was tested by different pouch or prototype cell.

2. Result and discussion

In this work, pouch cells were assembled to evaluate the capacity, rate performance and cycle stability of a new hybrid battery capacitor based on Li4Ti5O12/AC/LiMn2O4/AC system. Large prismatic cells were designed to meet the demand of mass manufacturing. Results show that the Li4Ti5O12/AC/LiMn2O4/AC hybrid system can exhibit excellent cycling and rate performance. The pouch cell with a CN/CP ratio 1.01, containing 5 wt% AC in each electrode, shows superior electrochemical performance, 56.4 mAh g-1 specific capacity at 0.2 C and 72.2% capacity retention at 5 C rate. Besides, after 2000 cycles at the rate of 5 C, the capacity retention is 77.5%, achieving a large improvement of the cycle life compared to Li4Ti5O12/LiMn2O4 lithium-ion battery. 30 Ah large prismatic prototype achieves excellent cycle stability, the capacity retention is 90% and the ESR increases less than 10% after 5000 cycles at 2 C, 70% DOD.

Besides, To address the large-scale application demands of high energy density, high power density, and long cycle lifetime, 700-F hybrid capacitor pouch cells have been prepared, comprising ~240-μm-thick activated carbon cathodes, and ~60-μm-thick Li4Ti5O12 anodes. the obtained hybrid capacitors composed of an activated carbon (AC) and a M-LTO shows excellent cell performances, achieving an energy density of 57.35 Wh kg–1, a power density of 3,063 W kg–1, and ~92% capacitance retention after 10,000 cycles. The AC/M-LTO hybrid capacitors can meet the demands for large-scale applications such as trolleybus.

Biography:Ruan Dianbo is a senior engineer (Prof.) and Chief technologist of CRRC Corporation Limited (CRRC). With a PhD. from Tianjin University, Tianjin, He has been working on Supercapacitor for more than 15 years and firstly developed the highest organic supercapacitors (9500F and 12000F) around the word. Meantime, creatively using those cells as the main power for Low-floor tramcar and Energy storage trolleybus which made by CRRC. Right now, the former has been commercial running in Guangzhou Haizhou Line, and the latter also been operated in Ningbo, Zhejiang.
      After insisted on researching and producing for a long time, he has been awarded for National technical invention, Provincial prize and Provincial technological achievements appraisal. Until now, he has been researched and developed two generation products personally, and the generation-II supercapacitors have reached the international leading level.