Optimized Morphology and Tuning the Mn3+ Content of LiNi0.5Mn1.5O4 Cathode Material for Li-Ion Batteries

Abstract

The advantages of cobalt-free, high specific capacity, high operating voltage, low cost, and environmental friendliness of spinel LiNi0.5Mn1.5O4 (LNMO) material make it one of the most promising cathode materials for next-generation lithium-ion batteries. The disproportionation reaction of Mn3+ leads to Jahn–Teller distortion, which is the key issue in reducing the crystal structure stability and limiting the electrochemical stability of the material. In this work, single-crystal LNMO was synthesized successfully by the sol-gel method. The morphology and the Mn3+ content of the as-prepared LNMO were tuned by altering the synthesis temperature. The results demonstrated that the LNMO_110 material exhibited the most uniform particle distribution as well as the presence of the lowest concentration of Mn3+, which was beneficial to ion diffusion and electronic conductivity. As a result, this LNMO cathode material had an optimized electrochemical rate performance of 105.6 mAh g−1 at 1 C and cycling stability of 116.8 mAh g−1 at 0.1 C after 100 cycles.

Understanding the Correlation between Electrochemical Performance and Operating Mechanism of a Co-free Layered-Spinel Composite Cathode for Na-Ion Batteries

“…A minor amount of Mn 3+ is usually present in LTMOs due to the oxygen loss during the high temperature synthesis process. 53,54 This result agrees with the XPS fitting results, as it indicates the presence of a minor amount of Mn 3+ in the material, even though XPS gives information on the surface oxidation states and not bulk. The position of the Fe K edge in the XANES region overlaps with that of the reference sample Fe 2 O 3 , indicating a bulk oxidation state of +3 for Fe in the LS-NMNF pristine sample.…”

“…The position of the Mn K edge spectrum of the pristine sample lies at higher energies than that of Mn 2 O 3 and slightly less than that of MnO 2 , indicating that the major bulk oxidation state of Mn is +4 in the sample, with slight contribution from Mn 3+ . A minor amount of Mn 3+ is usually present in LTMOs due to the oxygen loss during the high temperature synthesis process. , This result agrees with the XPS fitting results, as it indicates the presence of a minor amount of Mn 3+ in the material, even though XPS gives information on the surface oxidation states and not bulk. The position of the Fe K edge in the XANES region overlaps with that of the reference sample Fe 2 O 3 , indicating a bulk oxidation state of +3 for Fe in the LS-NMNF pristine sample.…”

Comparison of lithium sources on the electrochemical performance of LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries

“…The primary issue with LNMO is the occurrence of degradation reactions in high-voltage operation that potentially cause corrosion reactions in the interface region between the cathode and electrolyte, resulting in low rate stability, especially at high temperatures (Ghosh et al, 2021;Yi et al, 2016). Therefore, several previous studies have majorly explored many aspects of modification, such as coating (Ku et al, 2019), structure (Yi et al, 2009), morphology (Lin et al, 2023), electrolyte optimization (Guo et al, 2022), and element doping (Kosova et al, 2016).…”

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

“…However, the higher working voltage of LNMO exceeds the stability of the electrolyte (working potential window at about 4.3 V), leading to the electrolyte oxidative decomposition and resulting in some side-reactions between the LNMO/electrolyte interface. Moreover, the reaction between LNMO and HF can result in the transition metals dissolution, thereby damaging the crystal structure of LNMO and resulting in poor cycling performance [2,3] .…”