title: Tunable and robust phosphite-derived surface film to protect lithium-rich cathodes in lithium-ion batteries.
abstract: A thin, uniform, and highly stable protective layer tailored using tris(trimethylsilyl) phosphite (TMSP) with a high tendency to donate electrons is formed on the Li-rich layered cathode, Li1.17Ni0.17Mn0.5Co0.17O2. This approach inhibits severe electrolyte decomposition at high operating voltages during cycling and dramatically improves the interfacial stability of the cathode. The TMSP additive in the LiPF6-based electrolyte is found to preferentially eliminate HF, which promotes the dissolution of metal ions from the cathode. Our investigation revealed that the TMSP-derived surface layer can overcome the significant capacity fading of the Li-rich cathode by structural instability ascribed to an irreversible phase transformation from layered to spinel-like structures. Moreover, the superior rate capability of the Li-rich cathode is achieved because the TMSP-originated surface layer allows facile charge transport at high C rates for the lithiation process.
authors.affiliation: †School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798, South Korea.
authors.forename: Jung-Gu
authors.initials: JG
authors.lastname: Han
authors.affiliation: †School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798, South Korea.
authors.forename: Sung Jun
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: †School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798, South Korea.
authors.forename: Jaegi
authors.initials: J
authors.lastname: Lee
authors.affiliation: ‡Department of Chemical Engineering, Dong-A University, Busan 604-714, South Korea.
authors.forename: Jeom-Soo
authors.initials: JS
authors.lastname: Kim
authors.affiliation: §School of Chemical and Biological Engineering, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-744, South Korea.
authors.forename: Kyu Tae
authors.initials: KT
authors.lastname: Lee
authors.affiliation: †School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798, South Korea.
authors.forename: Nam-Soon
authors.initials: NS
authors.lastname: Choi
keywords: electrolyte additive; lithium-ion battery; lithium-rich layered cathode; solid electrolyte interphase; tris(trimethylsilyl) phosphite