Novel Battery Concepts Based on Semi-Solid Electrodes: The Injectable Battery

Abstract

Energy storage systems are present in our day-to-day life in portable devices or electric vehicles amongst others, being Li-ion batteries the technology that dominates the market due to its high energy and power densities. However, the increasing battery demanding requirements together with the concerns related to the availability of materials such as Co or Li, have brought much attention towards innovative battery concepts such as redox flow batteries or batteries based on semi-solid electrodes (SSEs). In particular, SSEs, which are dense slurries that are made of active and conductive materials and electrolyte in the absence of binder, offer some advantages in comparison to conventional electrodes. SSEs can reach higher mass loading than conventional electrodes increasing the battery areal capacity.[1] Their properties can be easily tuned by changing the ratio between active material, electrolyte and conductive material. In addition, the lack of binder confers to SSEs flowability and plasticity. These features make SSEs a promising type of electrodes for a wide range of battery application.This contribution will focus on the properties of SSEs and their application in batteries. In the first part of this contribution, recent progress on two innovative battery concepts based on SSEs will be presented: the easily-recyclable injectable battery (Figure 1a) and the shape-conformable injectable batteries (Figure 1b). The former concept is based on the fabrication of a cell leaving cavities to be filled with SSEs in a subsequent step. Once the end-of-life is reached, SSEs are dejected, having the entire cell ready to be injected with fresh SSE. In the latter concept, 3D printed injectable batteries are fabricated with complex shapes by combining additive manufacturing and SSEs. In the second part of the contribution, essential developments of analytical techniques for the study of intrinsic properties of SSEs will be discussed. It should be noted that the special features of SSEs, which can be easily tuned by adjusting their formulation, require specific tools to study their properties. Several specially designed cells for investigating various properties of SSEs will be disclosed. Acknowledgments This work has received funding from the Spanish Ministry of Science and Innovation and NextGenerationEU (TED2021-131651B-C21). This work was also supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union NextGenerationEU / PRTR References [1] D. Muñoz-Torrero, J. Palma, R. Marcilla, E. Ventosa, Al-Ion Battery Based on Semisolid Electrodes for Higher Specific Energy and Lower Cost, ACS Appl. Energy Mater. 3 (2020). Figure 1