A Novel NASICON‐Type Na₄MnCr(PO₄)₃ Demonstrating the Energy Density Record of Phosphate Cathodes for Sodium‐Ion Batteries

Abstract

Sodium‐ion batteries (SIBs) have attracted incremental attention as a promising candidate for grid‐scale energy‐storage applications. To meet practical requirements, searching for new cathode materials with high energy density is of great importance. Herein, a novel Na superionic conductor (NASICON)‐type Na4MnCr(PO4)3 is developed as a high‐energy cathode for SIBs. The Na4MnCr(PO4)3 nanoparticles homogeneously embedded in a carbon matrix can present an extraordinary reversible capacity of 160.5 mA h g−1 with three‐electron reaction at ≈3.53 V during the Na+ extraction/insertion process, realizing an unprecedentedly high energy density of 566.5 Wh kg−1 in the phosphate cathodes for SIBs. It is intriguing to reveal the underlying mechanism of the unique Mn2+/Mn3+, Mn3+/Mn4+, and Cr3+/Cr4+ redox couples via X‐ray absorption near‐edge structure spectroscopy. The whole electrochemical reaction undergoes highly reversible single‐phase and biphasic transitions with a moderate volume change of 7.7% through in situ X‐ray diffraction and ex situ high‐energy synchrotron X‐ray diffraction. Combining density functional theory (DFT) calculations with the galvanostatic intermittent titration technique, the superior performance is ascribed to the low ionic‐migration energy barrier and desirable Na‐ion diffusion kinetics. The present work can offer a new insight into the design of multielectron‐reaction cathode materials for SIBs.

Functional Passivation Interface of LiNi0.8Co0.1Mn0.1O2 toward Superior Lithium Storage

“…Herein, the passivation layer consisted of LiNiPO 4 with heteroatom (Co, Mn) doping could improve Li + migration. [ 19 ] Moreover, the density of states for heterogeneous interface exhibit metallic properties (Figure 7c) and fractional P–TM bond is preserved in the interface of NCM, [ 31 ] which enhances the electronic conductivity of the material at the heterogeneous interface. Therefore, overall, this strategy enhances the electrochemical activity of electrode materials and does not limit the Li + diffusion across cathode materials except at the initial stage.…”

Boosting Transport Kinetics of Cobalt Sulfides Yolk–Shell Spheres by Anion Doping for Advanced Lithium and Sodium Storage

“…[1][2][3][4][5] Although some renewable energy sources, such as solar, wind, and tidal energy, have alleviated the problem of environmental pollution to some extent, this situation has not been fundamentally resolved in the face of increasing demand for energy-storage devices. [6][7][8][9] Fortunately, the rapid development of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) has mitigated some concerns. [10,11] However, the commercial graphite anode material exhibits a low specific capacity (only 372 mAh g À1 ) in LIBs and inferior sodium-storage activity for SIBs, which seriously hinders the development of secondary rechargeable batteries.…”

“…Recently, transition-metal sulfides (TMSs) have been widely used as anode materials in LIBs and SIBs owing to their excellent electronic conductivity, high theoretical capacity, and abundant redox chemical properties. [8,13,[15][16][17][18] Among them, Co and S can be combined to form various forms of compounds with different valence states such as CoS, [19][20][21] CoS 2 , [22][23][24] Co 3 S 4 , [13,25,26] Co 9 S 8 , [27][28][29] and others, which endows them as potential anode materials with high theoretical specific capacity and superior thermal stability. However, the issues of rapid capacity decay, poor reaction kinetics, and severe polarization owing to volume changes during electrochemical reactions are still huge challenges for cobalt sulfides in practical applications.…”

Design Strategies of 3D Carbon‐Based Electrodes for Charge/Ion Transport in Lithium Ion Battery and Sodium Ion Battery

“…The DFT is the most common method to elucidate the ions migration paths and barriers and predict new material properties. [ 145 ] Interestingly, through tuning the values of Young's modulus ratio of 3D electrode can control 3D anisotropic properties, because it can cause the changes of lithiation expansion coefficient ratio. [ 29 ] Moreover, a series of geometrical parameters caused by 3D architectural structure can be investigated through the computational simulation method, which are hard to ascertain according to experimental measures.…”

“…To clarify the electrochemical kinetics of electrodes, the ion diffusion capability is commonly investigated by three measurements that are galvanostatic intermittent titration technique (GITT) measurement, CV curves at different scan rates, and EIS. [ 113,145,147 ]…”