Mouad Dahbi

Negative electrodes for Na-ion batteries

Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, current collectors, electrolytes and electrode/electrolyte interphase and its stabilization are essential for long cycle life Na-ion batteries. This paper also addresses the prospect of Na-ion batteries as low-cost and long-life batteries with relatively high-energy density as their potential competitive edge over the commercialized Li-ion batteries.

Synthesis of hard carbon from argan shells for Na-ion batteries

Hard carbon is an attractive material for negative electrodes in sodium-ion batteries. Herein, we report a new hard carbon synthesized via carbonization of argan shell biomass, which delivers an enhanced capacity higher than 330 mA h g−1 based upon reversible sodium insertion. We prepared hard carbon under different high-temperature treatment and biomass pretreatment conditions. The graphitization degree of the hard carbon increased as the carbonization temperature increased; simultaneously, the reversible capacity for sodium storage was significantly influenced by the carbonization temperature. Structural characterization revealed differences in the structures of the hard carbons synthesized at different carbonization temperatures, which elucidates the correlation between the increased capacity and the micropore size available for sodium storage. The composite electrodes containing the argan hard carbons with a sodium polyacrylate binder were tested in non-aqueous sodium half cells. The electrodes delivered reversible capacities as high as 300 mA h g−1 at a current density of 25 mA g−1 with superior reversibility and capacity retention of 94.1% after 70 cycles. By carbonization of argan shell biomass treated with HCl aqueous solution, we successfully demonstrated a higher reversible capacity of 333 mA h g−1 and an excellent capacity retention of 96.0% after 100 cycles.

Towards K-Ion and Na-Ion Batteries as “Beyond Li-Ion”

Li-ion battery commercialized by Sony in 1991 has the highest energy-density among practical rechargeable batteries and is widely used in electronic devices, electric vehicles, and stationary energy storage system in the world. Moreover, the battery market is rapidly growing in the world and further fast-growing is expected. With expansion of the demand and applications, price of lithium and cobalt resources is increasing. We are, therefore, motivated to study Na- and K-ion batteries for stationary energy storage system because of much abundant Na and K resources and the wide distribution in the world. In this account, we review developments of Na- and K-ion batteries with mainly introducing our previous and present researches in comparison to that of Li-ion battery.

Fluorine Chemistry for Negative Electrode in Sodium and Lithium Ion Batteries

Fluorine chemistry plays an important role in the development of materials for lithium-ion batteries. Throughout this chapter, we shed light on fluorine chemistry for sodium-ion batteries, especially carbonaceous materials and sodium alloy/compounds as negative electrode materials. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, electrolytes, electrode/electrolyte interphase, and its stabilization are essential for long cycle life. Electrochemical formation of lithium silicide is also described. Indeed, fluorinated ethylene carbonate is an effective electrolyte additive. This chapter also addresses the corrosion of the aluminum current collector at high potential, depending on the nature on the electrolyte and fluorinated anions salts.

Study of electrochemical alkali insertion into carbonaceous materials

Electrochemical insertion of alkali metal (lithium or sodium) into carbon electrodes is studied in non-aqueous organic electrolytes at room temperature. The extent of insertion into carbon and its reversibility process were found to be affected by the type and particle size of the carbon materials. The possibility of designing an alkali-ion battery cell is discussed, using natural graphite, graphitized carbon black and carbon black as negative electrodes.

Rechargeable Na-ion batteries for large format applications

Recent advances of negative and positive electrode materials suitable for rechargeable sodium-ion cells will be overviewed and discussed in terms of large-scale electricity storage technology, along with the prospects for future developments.