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Characterization and Dissolution of HEV NiMH Batteries

Kristian Larsson (Institutionen för kemi- och bioteknik)
Göteborg : Chalmers University of Technology, 2010.
[Licentiatavhandling]

The recycling of batteries is an important issue in a sustainable society where materials recycling of complex products is a necessity. Without an efficient recycling there will be an unnecessary loss of both materials and energy due to inefficient or non-existent recycling. This project concerns the recycling of nickel metal hydride (NiMH) hybrid electric vehicle (HEV) batteries and aims to outline the potentials and possibilities inherent in this waste stream. The main valuable metals in the batteries are nickel, cobalt and lanthanoids. The active cathode material is a triprecipitate of mainly nickel with zinc and cobalt in hydroxide form with yttrium and magnesium added, pasted onto a nickel metal foam-mesh support. The active anode material is a hydrogen absorbing alloy containing approximately 54% nickel and 31% lanthanoids and smaller amounts of manganese, cobalt, aluminium and yttrium. The recovery of these metals should be performed using a method which minimizes the use of energy and chemicals. The work presented in this thesis is a characterization of the batteries and a dissolution study of individual electrode materials as a first step in a hydrometallurgical recycling process. A nickel removal and purification process has also been investigated, the so called Mond process, by which nickel reacts with carbon monoxide and forms nickel tetracarbonyl. The nickel tetracarbonyl both forms and is highly volatile at a low temperature, unlike other relevant carbonyl compounds. This means that the volatilized nickel can easily be separated from the rest of the material and thereby purified. This gives both pure nickel and an interesting residue to work with. The positive electrode active material, nickel hydroxide, can be dissolved without dissolving the electrode backing material (nickel metal). A rapid dissolution of the active material on the positive electrode can be achieved at low temperature and relatively low acid concentration (pH 0.5-1.5), while leaving the major part of the nickel metal undissolved. This is possible with all the acids tested, nitric, sulphuric and hydrochloric acid. Therefore the most suitable acid depends on the choice of process following the dissolution.

Nyckelord: Materials Recycling, Nickel metal hydride, Batteries, Characterization, Selective dissolution, Mond, Nickel tetracarbonyl



Denna post skapades 2010-05-07. Senast ändrad 2010-05-07.
CPL Pubid: 121360

 

Institutioner (Chalmers)

Institutionen för kemi- och bioteknik (2005-2014)

Ämnesområden

Kemi

Chalmers infrastruktur

Examination

Datum: 2010-05-28
Tid: 10:00
Lokal: KB auditorium, Kemigården 4, Chalmers
Opponent: Ingmar Persson

Ingår i serie

Licentiatuppsatser vid Institutionen för kemi- och bioteknik, Chalmers tekniska högskola