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

Abstract

BackgroundLiCoO2 is one of the most used cathode materials in Li-ion batteries. Its conventional synthesis requires high temperature (>800 °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.ResultsSeveral 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 °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.ConclusionsOur 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-017-0292-3) contains supplementary material, which is available to authorized users.

Early‐Stage Sustainability Evaluation of Nanoscale Cathode Materials for Lithium Ion Batteries

“… nano‐LCO: According to our experimental measurements, the capacity is 25 % higher than that of HT‐LCO . The value for the energy density was calculated from this specific capacity by using a potential of 3.9 V, and the number of charging cycles was assumed to be similar to that of HT‐LCO; nano‐LMP: With regard to capacity, 90 % of the value achieved by making nanoparticles of LMP and ball milling reported by Kwon and co‐workers was assumed; the value for the energy density was calculated from this by applying a value for the potential of 4.1 V . For the number of charging cycles, the same value as for LFP was used as both of these materials have a similar olivine structure. …”

“…nano‐LCO: According to our experimental measurements, the capacity is 25 % higher than that of HT‐LCO . The value for the energy density was calculated from this specific capacity by using a potential of 3.9 V, and the number of charging cycles was assumed to be similar to that of HT‐LCO;…”

“…These materials have a better Li‐ion diffusivity than conventional materials because of the smaller grain size. For instance, LMP in combination with carbon black could lead to a capacity up to 20 % higher than that of commercially used lithium iron phosphate (LFP) …”

Performance Improvements of Cobalt Oxide Cathodes for Rechargeable Lithium Batteries

“…Therefore, ultrafine LiCoO 2 powders have advantages over commercial LiCoO 2 powders. For example, the high initial charge/discharge capacities and rate capability has been confirmed . Xuanye et al.…”

“…Therefore, ultrafine LiCoO 2 powders have advantages over commercial LiCoO 2 powders. For example, the high initial charge/discharge capaci-ties and rate capability has been confirmed [38][39][40][41][42][43]. Xuanye et al [44] showed that ultrafine-sized LiCoO 2 exhibits a high initial discharge specific capacity of 166.7 mAh g -1 at 0.2°C.…”