NaMn_2-xNi_xO₄Derived from Mesoporous LiMn_2-xNi_xO₄: High-Voltage Spinel Cathode Materials for Na-Ion Batteries

Abstract

Sodium ion batteries are a topic of emerging interest, as the low cost and high natural abundance of sodium precursors provide a specific advantage over commercial lithium ion batteries. Comparatively, sodium chemistries suffer from lower operating voltages, making the development of suitable high voltage positive electrodes key to enabling sodium chemistries capable of direct replacement for modern lithium ion storage devices. Herein, we investigate dis/ordered nickel doped manganese spinels (Na x Mn 2-y Ni y O 4 ) as a positive electrode for sodium ion battery applications. Due to the kinetic limitations of the sodium de/insertion reaction into Na 1-x Mn 2-y Ni y O 4 the effect of both temperature and the electrochemical cycling window are studied revealing a unique reaction pathway and potential optimization routes for further study. Increasing interest in large-scale electrochemical energy storage for grid applications has prompted the investigation of battery chemistries that are more cost-effective as compared to commercial Li-ion technology. Due to the large abundance and associated low costs of sodium precursors, sodium-ion batteries have been widely investigated over recent years. Investigations into positive electrodes for sodium ion batteries (SIBs) have produced a number of different electrode chemistries capable of reversible Na + de/insertion. In particular, the manganese oxides have demonstrated a number of possible host structures suitable for reversible cycling of Na + , with the majority of attention being generally confined to layered compounds consisting of transition metal doped P2, P3, and O3 type structures. 1-4However, there still remain certain drawbacks in utilizing such SIBs for commercial applications, as reversible Na + de/insertion requires large open structures due to the physically larger ionic radii of Na + (∼1.0 Å) relative to that of Li + (0.59 Å). 5Of particular concern is the lower voltage of SIBs using traditional chemistries imparted by the Na/Na + redox, which is approximately 0.33 V higher than that of Li/Li + . Table I considers a competitive analysis of various cathode chemistries of potential interest for SIBs, and although suffering from a reduction in gravimetric and volumetric capacity when comparing against LIBs, movement from lithium to sodium chemistries offers considerable advantages in terms of cost and raw material abundance making them far more practical for electrical grid applications.Due to the large foundation of research on lithium-ion cathode materials, it is desirable to potentially utilize such promising structures for analogous cathodes in SIBs. The spinel structure has been widely studied, and offers facile Li + de/insertion by nature of the 3D interdiffusional pathways. However, the large ionic size differences between Li + and Na + have demonstrated considerable difficulty in the implementation of sodium analogues to existing Li-based compositions; yet the spinel structure has proven to successfully accommodate Na + following initial delithiation ...

Ab Initio Study of Sodium Insertion in the λ-Mn2O4 and Dis/Ordered λ-Mn1.5Ni0.5O4 Spinels

“…10,11 A flat voltage plateau in the region of 3.65 V vs Na/Na + is reported, which is 0.56 V higher than in the pure spinel, 10 followed by a sharp voltage decline toward the λ-Na 1 Mn 1.5 Ni 0.5 O 4 phase. 10,11 Both the ordered and the disordered phase display mixed phase separation and solid solution reaction pathways, the concentration ranges of which appear to depend on the cycling conditions. 10,11 Similar to Li-ion batteries, 20,25 the disordered phase exhibits better electrochemical performance, even though both the ordered and disordered structures have similar Li-ion diffusion coefficients.…”

“…20−25 The Ni distribution, and thus the resulting symmetry, strongly depends on the synthesis route of the lithiated counterpart (λ-LMNO), from which the delithiated host is obtained via electrochemical or chemical Li deinsertion. 10,11,21,24,25 Sodiation of the ordered and disordered λ-MNO spinels was recently studied by Kim and colleagues, who reported reversible Na (de)insertion in the tetrahedral (8a) interstitial sites of the spinel lattice. 10,11 A flat voltage plateau in the region of 3.65 V vs Na/Na + is reported, which is 0.56 V higher than in the pure spinel, 10 followed by a sharp voltage decline toward the λ-Na 1 Mn 1.5 Ni 0.5 O 4 phase.…”

“…10,11,21,24,25 Sodiation of the ordered and disordered λ-MNO spinels was recently studied by Kim and colleagues, who reported reversible Na (de)insertion in the tetrahedral (8a) interstitial sites of the spinel lattice. 10,11 A flat voltage plateau in the region of 3.65 V vs Na/Na + is reported, which is 0.56 V higher than in the pure spinel, 10 followed by a sharp voltage decline toward the λ-Na 1 Mn 1.5 Ni 0.5 O 4 phase. 10,11 Both the ordered and the disordered phase display mixed phase separation and solid solution reaction pathways, the concentration ranges of which appear to depend on the cycling conditions.…”

“…10,11 Both the ordered and the disordered phase display mixed phase separation and solid solution reaction pathways, the concentration ranges of which appear to depend on the cycling conditions. 10,11 Similar to Li-ion batteries, 20,25 the disordered phase exhibits better electrochemical performance, even though both the ordered and disordered structures have similar Li-ion diffusion coefficients. 11 Considerable kinetic barriers which hinder complete desodiation are reported, and nanosizing is suggested to achieve good performance.…”

Insights into the Synergistic Roles of Microwave and Fluorination Treatments towards Enhancing the Cycling Stability of P2-Type Na0.67[Mg0.28Mn0.72]O2Cathode Material for Sodium-Ion Batteries

“…Among them, layered P2-type manganese oxide (MnO 2 )-based materials have been widely studied and continued to attract major research interests as promising cathode materials for SIBs. [9][10][11][12][13][14][15][16][17] This is due to the abundance of manganese, importantly P2-type MnO 2 -based materials offer larger tunnels for the intercalation and de-intercalation of the sodium-ion and have been reported to have high capacities. [18][19][20] A sodium-ion layered oxide material crystallizes into either P2-type or O3-type structural phases or mixture of both.…”