Coating of NCM 851005 cathode material with Al0@Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and subsequent treatment with anhydrous HF

Martens, Arthur; Bolli, Christoph; Hoffmann, Anke; Erk, Christoph; Ludwig, Thilo; El Kazzi, Mario; Breddemann, Ulf; Novák, Petr; Krossing, Ingo

doi:10.1149/1945-7111/ab68d0

Coating of NCM 851005 cathode material with Al0@Al₂O₃ and subsequent treatment with anhydrous HF

Martens A, Bolli C, Hoffmann A, Erk C, Ludwig T, El Kazzi M, Breddemann U, Novák P & Krossing I

Citation

Martens, A., Bolli, C., Hoffmann, A., Erk, C., Ludwig, T., El Kazzi, M., … Krossing, I. (2020). Coating of NCM 851005 cathode material with Al0@Al₂O₃ and subsequent treatment with anhydrous HF. Journal of the Electrochemical Society, 167(7), 070510 (10 pp.). https://doi.org/10.1149/1945-7111/ab68d0

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:30112

The volatile alane (H₂AlO^tBu)₂ decomposes into amorphous HAlO or Al⁰@Al₂O₃ nanoparticles upon heating, depending on the time and temperature. By coating the Ni-rich cathode material NCM851005 with this compound, the NCM's cycling stability and electric conductivity were increased. Thus, the coating not only yielded Al⁰@Al₂O₃ nanoparticles but also, by reaction with surface Li₂O/LiOH/Li₂CO₃, a Li⁺ conductive LiAlO₂ layer. The coatings with 0.3 and 0.1 wt% (H₂AlO^tBu)₂, respectively, significantly reduced the resistance build-up to 70/115% after 280 cycles at 1 C (351% without coating). Upon treatment of the 0.3 wt% Al-coating with two equivalents of anhydrous HF, the Al₂O₃ and LiAlO₂ parts were transformed into a Li[AlO(OH)F] layer, which yielded better capacity retention, retaining the low impedance build-up of only +120% (280 cycles at 1 C). This treatment, however, proved to have the same effect as simply reducing the amount of (H₂AlO^tBu)₂ for the coating to 0.1%.