Failure Mechanisms of High-Voltage Spinel LiNi_0.5Mn_1.5O₄ with Different Morphologies: Effect of Self-Regulation by Lithium Benzimidazole Salt Additive

Abstract

High voltage (∼5 V) spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) has attracted great attention because of its ultrahigh voltage plateau, which can be used as a cathode to reduce pressure in battery management systems. Moreover, compared with layered LiN x M y C z O 2 materials, LNMO only requires little amounts of Ni, is cobalt-free for maintaining energy density, is inexpensive, and is lightweight. This study demonstrates two types of primary particles with different morphologies: rectangular and pentahedral. The pentahedron-shaped LNMO has lower surface energy owing to the formation of high valence Ni on the surface, thereby causing gas evolution and a loss in cycle retention, a direct Ni 2+ /Ni 4+ reaction. Conversely, rectangular-shaped LNMO with higher Mn 3+ content exhibits a stable electrochemical reaction, which provides a higher surface energy that prevents ethylene carbonate (EC) decomposition on the surface, and thereby, excellent performance is obtained, a parallel reaction of Mn 3+ / Mn 4+ and Ni 2+ / Ni 3+ . By adding a lithium salt additive, trifluoromethyl benzimidazole (LiTFB), a self-regulation of Ni and Mn ion valences leads to a key reaction on both pentahedral (surface disordering effect) and rectangular (preventing Jahn−Teller distortion effect) LNMO morphologies. The two-electron transfer in the reactions of Ni 2+/3+ and Mn 3+/4+ of LiTFB-modified LNMOs provides excellent electrochemical performance for further high-energy applications.

Diethyl (4-isopropylbenzyl) phosphonate as an electrolyte additive for LiNi0.5Mn1.5O4 cathode for high-voltage Li-ion battery

“…The addition of DLPP in STD electrolyte suppresses the side reactions, forms a thinner CEI layer and improves the structural stability of electrode material. Furthermore, the formed CEI layer with DLPP additive restrains the HF corrosion and reduce the transition metal dissolution, thus enhancing the cycling performances of the battery [11,12] .…”

Study on the (trimethoxysilyl) naphthalene electrolyte additive for enhancing electrochemical performance of LiNi0.5Mn1.5O4 cathode for Li-ion battery

“…3(b, c) shows the charge-discharge curves of LNMO/Li half-cells after the 100 and 200 cycles. It can be observed that the LNMO/Li half-cell from 100 th to 200 th after 100 cycles, the LNMO/Li half-cell in STD+0.5% TMSN exhibits smaller potential difference than that in STD, indicating TMSN additive in electrolyte can reduce the electrode polarization, thus a lower interfacial reaction resistance of LNMO electrode was obtained from the addition of TMSN additives [10][11][12][13]. In summary, the CEI constructed with TMSN possesses protective properties, greatly inhibits the corrosion HF to active material and reduce the increase in interface resistance, thus enabling the LNMO/Li half-cell to have better cycling performance.…”