A long-lasting dual-function electrolyte additive for stable lithium metal batteries. (September 2020)

• Record Type: Journal Article
• Authors: Wang, Dongdong; Liu, Haodong; Li, Mingqian; Xia, Dawei; Holoubek, John; Deng, Zhi; Yu, Mingyu; Tian, Jianhua; Shan, Zhongqiang; Ong, Shyue Ping; Liu, Ping; Chen, Zheng
• Is Part Of: Nano energy. Volume 75(2020)
• Publication Date: 2020-09
• Subjects: Potassium nonafluoro-1-butanesulfonate additive -- Solid electrolyte interphases -- Li anodes -- Li metal batteries -- High areal capacity; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2020.104889
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Solid electrolyte interphases (SEI) plays a vital role in stabilizing lithium (Li) metal anodes for rechargeable batteries. However, forming robust SEI layers is challenging in the state-of-the-art electrolytes. Herein, we report a long-lasting and dual-function additive (potassium nonafluoro-1-butanesulfonate or KPBS) for dual-salt LiFSI-LiTFSI ether electrolyte. Our work suggests that the electrostatic shield effect from potassium ion (K + ) and the F-rich PBS − anions with a middle lowest unoccupied molecular orbital (LUMO) level together promote the formation of a LiF-rich SEI during the Li plating/striping process, which effectively restricts Li dendrite growth and suppresses electrolyte consumption. As a consequence, the designed electrolyte endows small nucleation overpotential, highly reversible Li plating/stripping, and excellent cycling stability. Specifically, with such an electrolyte, Li–Cu cells can maintain stable cycling during 400 cycles at 1 mA cm −2 for 1 mA h cm −2 with a high coulombic efficiency (CE) of 99.1%. Li–LiFePO4 full cells displayed dramatically improved cycling stability after 100 cycles with high CE of 99.6% under relatively lean electrolyte condition (7.5 μL mA h −1 ), limited Li supply (N/P = 1.2) and high areal capacity (4.1 mA h cm −2 ). Graphical abstract: Image 1 Highlights: A long-lasting electrolyte additive, KPBS, promoting the formation of robust LiF-rich SEI layer on the anode side was discovered. The K + cations can offer effective electrostatic shielding that prevents the formation of Li-metal "hot-spots". The F-rich PBS − anions with a unique lowest unoccupied molecular orbital (LUMO) level is responsible for the formation of LiF-rich SEI layer. Li–LiFePO4 full cells with KPBS showed improved cycling stability with relatively lean electrolyte, limited Li supply and high areal capacity. The electrolyte additive shows promise for practical Li-metal cell applications.