Na-ion BATTERIES

The demand for inexpensive and effective energy storage technologies is rapidly increasing. The imminent exhaustion of fossil fuel resources and the environmental consequences related to their use, combined with the rapid development of renewable energy sources, promote the scientific community to develop advanced energy storage systems. Among the several technologies that are suitable for large-scale energy storage, rechargeable batteries appear as one of the most promising options.

Sodium-ion batteries (NIB) appear as a promising alternative to the well-established lithium batteries technology. Sodium natural resources are unlimited everywhere, being sodium the 4th most abundant element on earth. Additionally, sodium insertion materials have been extensively studied over the last few years as promising candidates to be used as cathodes in sodium batteries.

We present here a comprehensive description of the electrochemical behavior of Na-Ion and Li-Ion full cells, using hard carbon as the anode material, NaNi_0.5Mn_0.5O₂ and LiNi_0.5Mn_0.5O₂ as the cathodes. A detailed description of the structure, phase transition, electrochemical behavior and kinetics of NaNi_0.5Mn_0.5O₂ cathodes is presented, including interesting comparison with their lithium analog. The critical effect of the hard carbon anodes structure, pretreatment and selection of both binder and additives in the total capacity and stability of full cells is clearly demonstrated. We discuss possible reasons for capacity fading of these systems, its connection to the cathode structure and relevant surface phenomena