Characteristics and properties of nano-LiCoO2 synthesized by pre-organized single source precursors: Li-ion diffusivity, electrochemistry and biological assessment

Background: LiCoO2 is one of the most used cathode materials in Li-ion batteries. Its conventional synthesis requires high temperature (>800 degrees C) and long heating time (>24 h) to obtain the micronscale rhombohedral layered high-temperature phase of LiCoO2 ( HT-LCO). Nanoscale HT-LCO is of interest to improve the battery performance as the lithium (Li+) ion pathway is expected to be shorter in nanoparticles as compared to micron sized ones. Since batteries typically get recycled, the exposure to nanoparticles during this process needs to be evaluated. Results: Several new single source precursors containing lithium (Li+) and cobalt (Co2+) ions, based on alkoxides and aryloxides have been structurally characterized and were thermally transformed into nanoscale HT-LCO at 450 degrees C within few hours. The size of the nanoparticles depends on the precursor, determining the electrochemical performance. The Li-ion diffusion coefficients of our - LiCoO2 nanoparticles improved at least by a factor of 10 compared to commercial one, while showing good reversibility upon charging and discharging. The hazard of occupational exposure to nanoparticles during battery recycling was investigated with an in vitro multicellular lung model. Conclusions: Our heterobimetallic single source precursors allow to dramatically reduce the production temperature and time for HT-LCO. The obtained nanoparticles of LiCoO2 have faster kinetics for Li+ insertion/extraction compared to microparticles. Overall, nano-sized - LiCoO2 particles indicate a lower cytotoxic and (pro-)inflammogenic potential in vitro compared to their micron-sized counterparts. However, nanoparticles aggregate in air and behave partially like microparticles

Advances in cathode nanomaterials for lithium-ion batteries

Energy resources, consumption, and management are among the most important issues of this century. Our dependence on fossil fuels should be changed by eco-friendlier renewable energies. Further, the generated electrical energy should be stored for improving mobile applications, being batteries the most used system for this purpose. Lithium-ion batteries are the most promising battery type and are composed of three main elements: cathode, anode, and separator/electrolyte. The active material of the cathode is primarily responsible for the battery capacity, and for that reason, different cathode materials have been developed and explored for lithium-ion batteries. In the present work, the most relevant cathode materials are presented, their main properties and characteristics described, and their advantage and disadvantage analyzed, allowing to understand to which extent those materials are suitable for specific applications in this field.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 project PTDC/CTM-ENE/5387/2014, project no. PTDC/FISMAC/28157/2017, and grant SFRH/BPD/112547/2015 (C.M.C.). The authors thank the Basque Government Industry Department under the ELKARTEK and HAZITEK Programs for its financial support