Treatment and Electrochemical Performance of Recycled Graphite from Spent Li-Ion Batteries

Basic data for this talk

Type of talk: scientific talk
Name of speakers: Sergej Rothermel
Date of talk: 24/03/2015
Talk language: English

Information about the event

Name of the event: 16th Topical Meeting of the International Society of Electrochemistry, Electrochemical Properties and Applications of Advanced Carbon Materials
Event location: Vila Galé, Angras dos Reis, Brazil

Abstract

Over the last two decades the use of Li-ion batteries (LIBs) is constantly increasing. With regards to environmental and economical sustainability, the European Parliament and the Council established guidelines for the treatment and recycling of spent LIBs stated in the Battery Directive 2006/66/EC. Consequently, member states are obligated to set up collection and recycling systems. Also, battery manufacturers have to ensure a recycling efficiency of at least 50% referenced to the average weight of the battery components by the year 2016. In addition, the recovered materials have to be reprocessed in a production process for their original or other purposes. Today the development of the recycling routes is primarily aimed at the recovering of the valuable components and materials such as Li, current collectors, transition metals from cathode materials and organic compounds from the electrolytes.[1] As a result of a high availability of graphite, the recycling of anodes is not in focus of interest so far. Taking into account that during the recycling process already solvent-free graphite is created as by-product and needs to be disposed, one has to consider whether the reprocessing of recycled graphite is more reasonable than its disposal effort. In this work, commercial lithium-ion 18650 cells were dismantled after their cycling to 70% state of health (SOH). The electrolyte was extracted using an autoclave extraction technique with supercritical helium head pressure carbon dioxide (sc HHPCO2).[2] Furthermore, the electrochemical performance of extracted and heat treated graphite was investigated in a three-electrode setup with metallic lithium as counter and reference electrode using a carbonate based electrolyte. Also the influence of SOH on the discharge capacity and Coulombic efficiency of recycled graphite is examined. The morphology of extracted graphite was closely studied by SEM technique and the surface of graphite particles was characterized by BET measurements as well as XPS. In addition, different treatment methods are evaluated, in order to modify the surface of extracted graphite particles, to remove the binder, decomposition products of the electrolyte and the SEI. [1] T. Georgi-Maschler, B. Friedrich, R. Weyhe, H. Heegn, M. Rutz, J. Power Sources 2012, 207, 173-182. [2] M. Grützke, V. Kraft, W. Weber, C. Wendt, A. Friesen, S. Klamor, M. Winter, S. Nowak, J. Supercrit. Fluids 2014, 94, 216-222.

Keywords: Recycling; Li-ion