XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3199
some PVDF molecules are destroyed. As observed from
O 1s XPS spectrums in Figure 4 (c1), the characteristic
peaks of the cathode electrode material LiNixCoyMn1-
x-y O2, C=O, metal oxide M-O2+, and atom O bonded with
carbonyl are presented at 529.9, 531.74, 532.41 eV, and
534.05 eV, respectively. After plasma treatment (Figure 4
(c2)), the relative content of LiNixCoyMn1‑x-yO2 decreased
from 16.49% to 7.32%, the content of C=O/M-O2+ is
increased from 81.43% to 83.85%, and the content of
O-C=O is increased from 2.09% to 2.56%. In addition,
new peaks of C-O are observed with plasma treatment.
Thus, it is concluded that the metal elements of cathode
materials are involved in the formation of metal fluorides,
and the content of hydrophilic groups increased, thereby
increasing the hydrophilicity of the positive electrode mate-
rial. The temperature within the plasma is of the order of
103–104 K (Samal, 2017). The presence of high tempera-
ture can result in the generation of hydrogen fluoride gas
as PVDF is decomposed, which promotes the formation of
metal fluorides (Zhang et al., 2021).
Figure 4 (d) shows the fitted XPS spectrums of Ni 2p
of cathode materials before and after plasma treatment.
The peaks of Ni3+ and Ni2+ are observed at 855.4 eV and
872.7 eV, respectively. After plasma treatment, part of the
trivalent nickel was reduced to a divalent nickel. Figure 4
(e) shows the fitted spectrums of Co 2p. After treatment,
the relative content of Co2+ at 796.72 eV increased from
55.78 to 33.41%, indicating a decrease in the content of
divalent cobalt. Figure 4 (f) shows the fitted spectrum of
Mn 2p. The valence of Mn is not affected by plasma treat-
ment. In summary, the oxidation generated by plasma
treatment generates metal oxides and fluorides. For NCM
materials, Ni is mainly divalent, Co is mainly trivalent, and
Mn participates in the formation of compounds with a tet-
ravalent valence. This is the result of the destruction of the
structure of the positive electrode material binder PVDF,
Figure 4. XPS results of cathode materials without and with plasma treatment (C1s (a), F1s (b), O 1s (c), Ni 2p (d), Co 2p (e),
and Mn 2p (f))
some PVDF molecules are destroyed. As observed from
O 1s XPS spectrums in Figure 4 (c1), the characteristic
peaks of the cathode electrode material LiNixCoyMn1-
x-y O2, C=O, metal oxide M-O2+, and atom O bonded with
carbonyl are presented at 529.9, 531.74, 532.41 eV, and
534.05 eV, respectively. After plasma treatment (Figure 4
(c2)), the relative content of LiNixCoyMn1‑x-yO2 decreased
from 16.49% to 7.32%, the content of C=O/M-O2+ is
increased from 81.43% to 83.85%, and the content of
O-C=O is increased from 2.09% to 2.56%. In addition,
new peaks of C-O are observed with plasma treatment.
Thus, it is concluded that the metal elements of cathode
materials are involved in the formation of metal fluorides,
and the content of hydrophilic groups increased, thereby
increasing the hydrophilicity of the positive electrode mate-
rial. The temperature within the plasma is of the order of
103–104 K (Samal, 2017). The presence of high tempera-
ture can result in the generation of hydrogen fluoride gas
as PVDF is decomposed, which promotes the formation of
metal fluorides (Zhang et al., 2021).
Figure 4 (d) shows the fitted XPS spectrums of Ni 2p
of cathode materials before and after plasma treatment.
The peaks of Ni3+ and Ni2+ are observed at 855.4 eV and
872.7 eV, respectively. After plasma treatment, part of the
trivalent nickel was reduced to a divalent nickel. Figure 4
(e) shows the fitted spectrums of Co 2p. After treatment,
the relative content of Co2+ at 796.72 eV increased from
55.78 to 33.41%, indicating a decrease in the content of
divalent cobalt. Figure 4 (f) shows the fitted spectrum of
Mn 2p. The valence of Mn is not affected by plasma treat-
ment. In summary, the oxidation generated by plasma
treatment generates metal oxides and fluorides. For NCM
materials, Ni is mainly divalent, Co is mainly trivalent, and
Mn participates in the formation of compounds with a tet-
ravalent valence. This is the result of the destruction of the
structure of the positive electrode material binder PVDF,
Figure 4. XPS results of cathode materials without and with plasma treatment (C1s (a), F1s (b), O 1s (c), Ni 2p (d), Co 2p (e),
and Mn 2p (f))