Distinct Reaction Characteristics of Electrolyte Additives for High-Voltage Lithium-Ion Batteries: Tris(trimethylsilyl) Phosphite, Borate, and Phosphate

• Published in: Electrochimica acta Vol. 215; pp. 455 - 465
• Main Authors: Han, Young-Kyu, Yoo, Jaeik, Yim, Taeeun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2016
• Subjects: additive; Battery electrolyte; first-principles calculation; high voltage; reaction mechanism; high voltage; reaction mechanism; first-principles calculation; Battery electrolyte; additive
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2016.08.131

•Reaction characteristics of additives for high-voltage batteries are investigated.•The additives themselves have difficulty decomposing even in the cation state.•HF- and LiF-scavenging reactions of their neutral and cation species are favorable.•The additives can remove HF and LiF in electrolyte and on electrode, respectively.•Particularly, direct LiF-scavenging ability on the cathode surface is excellent. Tris(trimethylsilyl) phosphite, tris(trimethylsilyl) borate, and tris(trimethylsilyl) phosphate are well known as effective electrolyte additives that noticeably improve the electrochemical performance of the cathode material in high-voltage lithium-ion batteries. It is essential to understand the reaction characteristics of such additives for developing novel electrolyte additives for high-voltage batteries. This work reports the distinct reaction characteristics of the three popular additives via first-principles calculations of self-decomposition reactions and reactivity with HF and LiF that significantly degrade the cell performance. Spontaneous decomposition reactions of their neutral and cation species are all thermodynamically unfavorable, which indicates that the additives themselves have difficulty decomposing even in the cation state. The HF- and LiF-scavenging reactions of their neutral and cation species are all very favorable. Our results indicate that the strong reactivity of additives can efficiently remove the undesired molecules HF and LiF in the electrolyte and on the cathode surface, respectively. In particular, LiF-scavenging ability on the cathode surface is excellent.