Sol–Gel Synthesis of Aliovalent Vanadium‐Doped LiNi_0.5Mn_1.5O₄ Cathodes with Excellent Performance at High Temperatures

Abstract

Extraordinary performance at elevated temperature is achieved for high-voltage spinel-phase LiNi0.5 Mn1.5 O4 cathodes prepared using an adipic-acid-assisted sol-gel technique and doped with vanadium. V-substitution in the Li sites (Wykoff position 8a) is confirmed by V K-edge X-ray absorption spectroscopy and Rietveld refinement (Li0.995 V0.005 Ni0.5 Mn1.5 O4 ). V-doped LiNi0.5 Mn1.5 O4 delivered a reversible capacity of approximately 130 and 142 mAh g(-1) at ambient and elevated temperature conditions, respectively. Furthermore, the Li0.995 V0.005 Ni0.5 Mn1.5 O4 phase rendered approximately 94 % and 84 % of initial capacity compared to approximately 85 % and 3 % for the LiNi0.5 Mn1.5 O4 phase after 100 cycles in ambient and elevated temperature conditions, respectively. The enhancements are mainly because of the suppression of Mn dissolution and unwanted side reaction with electrolyte counterpart, and to the increase in conductivity, improving the electrochemical profiles for the V-doped phase.

Truncated octahedral LiNi0.5Mn1.5O4 cathode material for ultralong-life lithium-ion battery: Positive (100) surfaces in high-voltage spinel system

“…However, the widespread application of this material is hindered by severe capacity fade, particularly at elevated temperatures [10,11], caused by side reactions with the electrolyte under high voltage and other complex performanceinfluencing factors [9,12,13]. Surface modification [14,15], cation doping [16,17], and creation of various nanostructured morphologies such as nanoparticles [18,19], hollow structure [20,21], nanorods [22,23], and coreeshell structure [24], have been employed to stabilize the material structure in order to improve the electrochemical performance. The interfacial behaviors between the surface of high-voltage spinel and electrolyte are highly depending on different morphologies and microstructures, so the synthesis of a tailor-made material should also regard appropriately controlled regular particle shapes as well as surface orientations that benefit electrochemical performance.…”

Importance of nanostructure for reversible Li-insertion into octahedral sites of LiNi0.5Mn1.5O4 and its application towards aqueous Li-ion chemistry

“…The conventional material also displays a similar pattern, but it is less symmetric compared to that of the electrospun material. Peak currents can be determined from the following equation: I p ¼ (2.69 Â 10 5 ) n 3/2 D Li nC o Li [14,15] where I p is the peak current density (mA cm À2 ), n is the number of electrons per reaction species, D Li is the Li-diffusion coefficient (cm 2 s À1 ), n is the scan rate (mV s À1 ), C o Li is the bulk concentration of lithium (0.0244 mol cm À3 calculated from the theoretical density of spinel). The diffusion coefficients for electrospun Li[Ni 0.5 Mn 1.5 ]O 4 are calculated to be~5.85 Â 10 À11 and~5.18 Â 10 À11 cm 2 s À1 for anodic and cathodic processes, respectively.…”

“…The ordered spinel loses oxygen reversibly on heating in air above 700 C; a Ni-rich rock-salt phase is formed on loss of oxygen and is reabsorbed into the spinel on cooling. However, the amount of rock-salt phase remaining in the spinel depends on the rate of cooling, and the associated oxygen deficiency introduces Mn 3þ and disorder into the spinel phase [14]. The energy of the Mn 4þ /Mn 3þ redox couple on Li-extraction is similar to that in the~4-V Li 1-x [Mn 2 ]O 4 spinel.…”

Carbon‐Coated Li3Nd3W2O12: A High Power and Low‐Voltage Insertion Anode with Exceptional Cycleability for Li‐Ion Batteries

“…The energy density of such Li-ion power packs can be further increased by replacing LiMn 2 O 4 with a high voltage cathode like LiNi 0.5 Mn 1.5 O 4 . [30][31][32][33] Regarding the suppression of ICL observed in the anodes, pre-lithiation is one of the effective approaches to overcome the issue which has been successfully adopted for conversion and alloy type anodes. [34][35][36][37] cell at various C rates between 2.95-3.9 V and b) plot of capacity vs. cycle number.…”