Effects of MoO 3 coating on the structure and electrochemical performance of high-voltage spinel LiNi 0.5 Mn 1.5 O 4
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ORIGINAL PAPER
Effects of MoO3 coating on the structure and electrochemical performance of high-voltage spinel LiNi0.5Mn1.5O4 Ni Bai 1 & Ya-jun Ma 1 & Ai-min Wang 1 & Xinjiang Luo 2 Received: 15 November 2019 / Revised: 7 November 2020 / Accepted: 17 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract High-voltage spinel LiNi0.5Mn1.5O4 cathode material suffers from degradation of electrochemical cycling performance, particularly at elevated temperatures, hindering its successful commercialization. Here, we report that coating this cathode material with MoO3 oxides shows significantly improved electrochemical cycling performance at both room and elevated temperatures. The coated LiNi0.5Mn1.5O4 half-cell has a capacity retention of only 76%, while it is 90%, 92%, and 93% for 1 wt%, 2 wt%, and 3 wt% MoO3-coated LiNi0.5Mn1.5O4, respectively, after 100 cycles at 55 °C. The improved electrochemical cycling performance is attributed to the stabilized structure of LiNi0.5Mn1.5O4 by migration of Mo6+ into the former, particularly in the surface region during the MoO3 coating process, accompanied by a reduction in surface Ni content and an initial NiO impurity. Furthermore, the electrolyte decomposition and Ni and Mn metal dissolution are reduced by surface MoO3 coating. Keywords Lithium-ion batteries . Spinel cathode . LiNi0.5Mn1.5O4 . Coating . MoO3
Introduction Lithium-ion batteries (LIBs) have attracted much attention for applications in electric vehicles and portable electronics in recent years due to their high energy density [1, 2]. To meet the ever increasing energy requirement of electronic devices, one of the options is to increase the operating voltage of LIBs [3–6]. Spinel LiNi0.5Mn1.5O4 (LNMO) cathode material has a high operating voltage of 4.7 V vs. Li+/Li and a high specific capacity of 135 mA/g, making it an ideal cathode material for LIBs with high energy density [7–9]. Furthermore, due to the presence of mainly Ni and Mn elements in this cathode material, LNMO has a relatively low cost, high stability, and good environmentally benign properties [7, 8]. Moreover, this cathode material has 3D channels for lithium migration, enabling excellent rate
* Xinjiang Luo [email protected] 1
School of Chemistry and Chemical Engineering, Yulin University, No. 51 Chongwen Road, Yulin City 719000, Shaanxi Province, China
2
School of Electronics and Information, Hangzhou Dianzi University, Xiasha Higher Education Zone, Hangzhou City 310018, Zhejiang Province, China
capabilities [10, 11]. However, due to the high operating voltage, the electrochemical cycling performance degrades quickly, particularly at elevated temperatures [12–15], due to issues such as formation of a cathode-electrolyte interface (CEI) layer on the surface of the electrode [15–17] and distortion of the surface structure of the cathode material [7, 15, 18]. The LNMO cathode material is also subject to metal dissolution due to attack from HF that originates from the reaction between trace amounts of water and the el
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