The Hybrid Mineral Battery : energy storage and dissolution behavior of CuFeS₂ in a fixed bed flow cell Deen, K. M.; Asselin, Edouard
The development of a hybrid system, capable of storing energy, and with the additional benefit of Cu extraction is discussed in this work. A fixed bed flow cell (FBFC) was used in which a composite negative electrode containing CuFeS₂ (80 wt. %) and carbon black (20 wt. %) in graphite felt was separated from a positive (graphite felt) electrode by proton exchange membrane. The anolyte (0.2M H₂SO₄) and catholyte (0.5M Fe²⁺ in 0.2M H₂SO₄ with or without 0.1M Cu²⁺ addition) were circulated in the cell. With the addition of Cu²⁺ in the catholyte, the electrochemical activity of the Fe²⁺/Fe³⁺ redox couple over graphite felt was significantly improved. Ultimately, in the CuFeS₂||Fe²⁺/Cu²⁺ (CFeCu) FBFC system the specific capacity increased continuously to 26.4 mAh g-¹ in 500 galvanostatic charge/discharge (GCD) cycles, compared to the CuFeS₂||Fe²⁺ (CFe) system (13.9 mAh g-¹). Interestingly, the specific discharge energy gradually increased to 3.6 Wh kg-¹ in 500 GCD cycles for the CFeCu system compared to 3.29 Wh kg-¹ for the CFe system in 150 cycles. In addition to the energy storage, 10.75 % Cu was also extracted from the mineral, which is an important feature of CFeCu system as it would allow for Cu extraction and recovery through hydrometallurgical methods.
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