Ethanol

The LiNi_0.6Co_0.2Mn_0.2O₂ was synthesized via a molten-salt assisted method reported in our previous study^{26 ,35} . LiOH, Li₂SO₄, and ethanol were purchased from Adamas. The Ni_0.6Co_0.2Mn_0.2(OH)₂ was acquired from the GEM Co., Ltd. The Ni_0.6Co_0.2Mn_0.2(OH)₂ was mixed with LiOH, Li₂SO₄ with a molar ratio of 2:3:1 by grinding. The mixture was transferred into a cylindrical alundum crucible covered by a lid and heated to 950 °C with a ramping rate of 15 °C min⁻¹ for 3 h and then turn down to 900 °C for 10 h with a rate of 2 °C min⁻¹ in oxygen atmosphere before cooling down to 100 °C with a rate of 3 °C min⁻¹. The reaction mixture was removed from the excess Li-salts by washing with deionized water. The collected powder was dried at 80 °C in the air for 2 h before being thermally treated at 750 °C for 6 h in an oxygen atmosphere. Finally, the powder was passed through a 400-mesh sieve before testing.

High-purity graphite electrodes (99.9995%, metal basis, Alfa Aesar, Heysham, Britain), N,N-diethylformamide (DEF, 99%, Adamas, Shanghai, China), Zirconium(IV) Chloride (ZrCl₄, 98%, Adamas, Shanghai, China), Meso-tetra(4-carboxyphenyl)porphine (H₂TCPP, 98%, TCI, Tokyo, Japan), Benzoic acid (99%, Adamas, Shanghai, China), N,N-Dimethylformamide (DMF, 99.5%, Adamas, Shanghai, China), Hydrochloric Acid (HCl, 4 M, 37%, Adamas, Shanghai, China) acetone (99.5%, Adamas, Shanghai, China), Sodium Sulfate (Na₂SO₄, 99%, Greagent, Shanghai, China), Ethanol (99.5%, Adamas, Shanghai, China), Nafion ‘D-521 dispersion, 5% w/w in water and 1-propanol (Alfa Aesar, Heysham, Britain), TriEthanolamine (TEOA, 97%, Merk, Darmstadt, Germany), Diethyl ether (99.7%, Greagent, Shanghai, China).