Unsymmetrical fluorinated malonatoborate as an amphoteric additive for high-energy-density lithium-ion batteries. Issue 6 (16th April 2018)

• Record Type: Journal Article
• Authors: Han, Jung-Gu; Lee, Jae Bin; Cha, Aming; Lee, Tae Kyung; Cho, Woongrae; Chae, Sujong; Kang, Seok Ju; Kwak, Sang Kyu; Cho, Jaephil; Hong, Sung You; Choi, Nam-Soon
• Is Part Of: Energy & environmental science. Volume 11:Issue 6(2018)
• Page Start: 1552
• Page End: 1562
• Publication Date: 2018-04-16
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/c8ee00372f
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : A molecularly-engineered LiFMDFB additive constructs a protective layer for Li-rich cathodes while simultaneously strengthening the interface structure on SGC anodes. Abstract : High-capacity Si-embedded anodes and Li-rich cathodes are considered key compartments for post lithium-ion batteries with high energy densities. However, the significant volume changes of Si and the irreversible phase transformation of Li-rich cathodes prevent their practical application. Here we report lithium fluoromalonato(difluoro)borate (LiFMDFB) as an unusual dual-function additive to resolve these structural instability issues of the electrodes. This molecularly engineered borate additive protects the Li-rich cathode by generating a stable cathode electrolyte interphase (CEI) while simultaneously tuning the fluoroethylene carbonate (FEC)-oriented solid electrolyte interphase (SEI) on the Si–graphite composite (SGC) anode. The complementary electrolyte design utilizing both LiFMDFB and FEC exhibited an improved capacity retention of 85%, a high Coulombic efficiency of ∼99.5%, and an excellent energy density of ∼400 W h kg −1 in Li-rich/SGC full cells at a practical mass loading after 100 cycles. This dual-function additive approach offers a way to develop electrolyte additives to build a more favorable SEI for high-capacity electrodes.