Unraveling the Synergistic Effect of Mg and Ti Codoping to Realize an Ordered Structure and Excellent Performance for Sodium-Ion Batteries

Abstract

Layered cathodes have been recognized as potential advanced candidates for sodium-ion batteries (SIBs), but the poor electrochemical performance has seriously hindered their further development. Herein, an ordered Na2/3[Ni2/9Mg1/9Mn5/9Ti1/9]­O2 (NMMT) is designed and investigated as a high-performance cathode for SIBs through the synergistic effect of Mg and Ti codoping. Compared to the single Mg- or Ti-doped materials, NMMT clearly exhibits superstructure ordering diffraction peaks, and neutron diffraction further confirms that the diffraction peaks can be well indexed by a larger supercell P63, rather than the common unit cell P63/mmc by X-ray diffraction (XRD). High-resolution transmission electron microscopy also approves the ordering arrangement. This material shows an obvious capacity activation process during the first cycles, thus delivering 113 mA h g–1 specific capacity at 0.1 C (close to the theoretical value). Excellent rate capability even at 15 C and cycling stability after 500 cycles between 2.0 and 4.3 V can also be achieved, indicating that an ordered cathode is still promising. Besides, a single-phase reaction mechanism is revealed by ex situ/in situ XRD experiments. This study offers some insights into the material design and characterization of layered oxide cathodes for high-performance SIBs in the future.

In‐Plane BO3 Configuration in P2 Layered Oxide Enables Outstanding Long Cycle Performance for Sodium Ion Batteries

“…Moreover, even at relatively small discharge current of 2 C, the long cycle performance differences is also very large (Figure 3h). The NNCMB cathode material demonstrate an excellent capacity retention of 92.5% after 500 cycles and 80.1% after 1000 cycles at 2 C which is well comparable with those of the reported Na‐storage layered oxide cathodes, [ 39–50 ] as seen in Table S4 (Supporting Information). While for NNCM, after 500 cycles, the capacity shows a significant attenuation, indicating B doping can significantly improve the long cycle performance of P2‐Na 0.67 Ni 0.3 Co 0.1 Mn 0.6 O 2 materials.…”

“…As a result, the NNCM cathode material can only deliver reversible discharge capacities of 71.3, 62.4, and 57.3 mAh g −1 at 5 C, 10 C, and 20 C. The outstanding high-rate performance of NNCMB among those of the reported layered cathodes is highlighted in Figure 3f. [40][41][42][43][44][45][46][47][48] Considering the obvious polarization at the large C-rate of NNCM, long cycle performance of the samples at 5 C were tested to verify the cyclic stability of the two cathode materials (Figure 3g; and Figure S13, Supporting Information). For NNCMB cathode material, it demonstrates a satisfactory capacity retention of 88.3% after 300 cycles and maintains a similar curve shape with the first cycle (Figure 3g).…”

Zn/Ti/F synergetic-doped Na0.67Ni0.33Mn0.67O2 for sodium-ion batteries with high energy density

“…4e). [23][24][25][46][47][48][49][50][51][52][53][54] As indicated, the NNZMTOF cathode delivered better cycling performances in half-cells compared with that of other sodium-based layered oxide cathodes reported previously (Table S2 †).…”

Sodium titanate nanowires for Na+‐based hybrid energy storage with high power density

“…It is instructive to compare the rate performance of the optimized Mn‐NTO@C with a series of previously reported anode materials applied to SIBs, including O3‐Na 2/3 Ni 1/3 Ti 2/3 O 2 , 27 NFPP/rGO, 28 Na 2 Ti 6 O 13 @C, 29 Ti 3 CNT x , 30 Ti 3 C 2 T x‐ HF, 31 NMMT, 32 NDIC 14 , PSC‐NTP@C, 33 and I Pre ‐HC N 12 (Figure 5H). Not only does Mn‐NTO@C show an improved capacity at relatively low current densities compared to other anode materials, but it also delivers a favorable rate performance with the current density exceeding 10 A g −1 .…”