Dual-anion ionic liquid electrolyte enables stable Ni-rich cathodes in lithium-metal batteries

• DOI: 10.1016/j.joule.2021.06.014
• Publication Date: 2021-07-15T14:46:13Z
• Authors: Fanglin Wu; Shan Fang; Matthias Kuenzel; Angelo Mullaliu; Jae-Kwang Kim; Xinpei Gao; Thomas Diemant; Guk-Tae Kim; Stefano Passerini
• Keywords: Technology; ddc:600; cathode aging; cobalt-poor cathode; ionic liquid electrolyte; lithium-metal battery; Ni-rich cathode; info:eu-repo/classification/ddc/600; 600; 7. Clean energy; 01 natural sciences; 3. Good health; 0104 chemical sciences

High-energy-density lithium-metal batteries face the challenge of developing functional electrolytes enabling both stabilization negative electrode and high-voltage positive electrodes (> 4 V versus Li+/Li). Herein, a low-volatility non-flammable ionic liquid electrolyte (ILE) incorporating two anions, bis(fluorosulfonyl) imide (FSI) bis(trifluoromethanesulfonyl)imide (TFSI), is successfully applied to overcome this challenge, employing high-energy, low-Co, Ni-rich positive-electrode material, LiNi0.88Co0.09Mn0.03O2 (NCM88), in Li-metal batteries. With specific electrolyte, cathode exhibits remarkable electrochemical performance, achieving an initial capacity 214 mAh g−1 outstanding retention 88% over 1,000 cycles. More importantly, enables average Coulombic efficiency 99.94%. The excellent compatibility dual-anion ILE with lithium metal (50 μm) material realization cells energies more than 560 Wh kg−1 based on their combined active masses.