Enhancing the Electrochemical Performance of a High‐Voltage LiNi_0.5Mn_1.5O₄ Cathode in a Carbonate‐Based Electrolyte with a Novel and Low‐Cost Functional Additive

Abstract

Butyric anhydride (BA) is used as an effective functional additive to improve the electrochemical performance of a high‐voltage LiNi0.5Mn1.5O4 (LNMO) cathode. In the presence of 0.5 wt % BA, the capacity retention of a LNMO/Li cell is significantly improved from 15.3 to 88.4 % after 200 cycles at 1 C. Furthermore, the rate performance of the LNMO/Li cell is also effectively enhanced, and the capacity goes up to 112 mAh g−1 even at 5 C, which is considerably higher than that of a LNMO/Li cell in electrolyte without BA additive (95.4 mAh g−1 at 5 C). Linear sweep voltammetry and cyclic voltammetry results reveal that the BA additive can be preferentially oxidized to construct a stable cathode electrolyte interphase (CEI) film on the LNMO cathode. Subsequently, the BA‐derived CEI film can alleviate the decomposition of the electrolyte and the dissolution of Mn and Ni ions from the LNMO cathode as well as maintain the structural stability of LNMO during the cycling process; this leads to outstanding electrochemical performance. Thus, this work provides an effective and low‐cost functional electrolyte for high‐voltage LNMO‐based LIBs.

Antioxidation Mechanism of Highly Concentrated Electrolytes at High Voltage

“…Therefore, spinel LiNi 0.5 Mn 1.5 O 4 cathode has been considered as the most important candidate materials in LIBs for high working voltage (∼4.7 V vs Li/Li + ) and high energy density (∼650 W h kg –1 ). − However, conventional dilute electrolytes with lithium salt of 1mol L –1 (1 M) are prone to excessive decomposition in the process of matching this high-voltage cathode materials (>4.7 V), resulting in an increased irreversible capacity such as low initial Coulombic efficiency, poor cyclic stability, and low safety . To date, many efforts from the perspective of electrolytes have been made to solve this problem mainly including using additives such as borates, phosphonates, and acid anhydride, − and introducing oxidation-resistant auxiliary solvents, such as propylene carbonate (PC), sulfones, and nitriles. − However, the starting point of these methods have the problem of incompatibility between the electrolyte and the electrode. , Therefore, it is significantly important to deeply understand the oxidation decomposition mechanism of the electrolyte and find an effective strategy to improve the compatibility of electrolyte solutions with high-voltage cathode materials in LIBs.…”

Stabilized Cathode Interphase for Enhancing Electrochemical Performance of LiNi0.5Mn1.5O4-Based Lithium-Ion Battery via cis-1,2,3,6-Tetrahydrophthalic Anhydride

“…The CEI film can effectively suppress the dissolution of transition metal cations, prevent the decomposition of the electrolytes, and finally improve the cyclic ability of LNMO-based LIBs. In our previous work, we found that the butyric anhydride (BA) as a film-forming additive can also construct a stable LNMO interphase film and further enhance the electrochemical properties of LNMO at a voltage from 3.5 to 4.9 V. 36 Subsequently, it was revealed that, in the CEI film, there exists a remarkable difference in the microstructure, stability, and function when anhydrides have different molecular structures as film-forming additives. 37 Furthermore, Li's group found that 4-fluorophenyl acetate as the additive can improve the stability of the solid electrolyte interphase more efficiently, due to the aromatic ring.…”

Enhanced Electrochemical Performance of 5V LiNi0.5Mn1.5‐xZrxO4 Cathode Material for Lithium‐Ion Batteries

“…Therefore, developing cathode materials with high operating voltage is an effective way to improve the energy density of LIBs, such as olivine LiMPO 4 (M=Mn, Ni, Co), layered nickel‐rich LiNi x Co y Mn 1‐x‐y O 2 (x≥0.8) and lithium‐rich xLi 2 MnO 3 ⋅ (1‐x)LiMO 2 (M=Mn, Ni, Co, Fe, Cr, etc. ), as well as spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) [2] . Among them, LiNi 0.5 Mn 1.5 O 4 material has attracted more attention due to high operating voltage (∼4.7 V vs .…”

“…With the rapid development of new‐energy vehicle industry, the demand for lithium‐ion batteries (LIBs), as the main power supply for electric vehicles, is growing rapidly [1] . The energy density of LIBs is determined by specific capacity and operating voltage [2] . Therefore, developing cathode materials with high operating voltage is an effective way to improve the energy density of LIBs, such as olivine LiMPO 4 (M=Mn, Ni, Co), layered nickel‐rich LiNi x Co y Mn 1‐x‐y O 2 (x≥0.8) and lithium‐rich xLi 2 MnO 3 ⋅ (1‐x)LiMO 2 (M=Mn, Ni, Co, Fe, Cr, etc.…”