Shape‐Induced Kinetics Enhancement in Layered P2‐Na_0.67Ni_0.33Mn_0.67O₂ Porous Microcuboids Enables High Energy/Power Sodium‐Ion Full Battery

Abstract

P2‐type Na0.67Ni0.33Mn0.67O2 cathode material generally suffers from poor cycling and rate performance due to fiercely phase variation and low Na+ diffusion kinetic. Although efforts have been made to promote the electrochemical properties through ionic doping, the specific capacity reduction in most cases since the doped cations are electrochemical inactive cannot be neglected. Recently, some pioneering work have demonstrated that the advanced morphological design could significantly improve Na+ intercalation kinetics. But rare researches devote to improving the electrochemical performance on P2‐type Na0.67Ni0.33Mn0.67O2 through morphological manipulation. Herein, unique one‐dimensional P2‐type Na0.67Ni0.33Mn0.67O2 porous microcuboids with abundantly exposed {010} facets have been well designed via a simple one‐pot strategy. Due to the reasonable material design, it demonstrates unprecedented electrochemical performances. Particularly, it can deliver high rate performance with 122.1 mAh g−1 at 5 C, extraordinary cycle life with a capacity retention of 94.6 % after 1500 cycles at 5 C. More importantly, prototype sodium ion full cell could achieve state‐of‐the‐art power density of 1383.1 W kg−1 with high energy density of 84.7 Wh kg−1. The underlying mechanism of enhanced electrochemical properties of this well‐designed material has been deciphered through dynamic analysis, in‐situ X‐ray diffraction and structural analysis after cycling.

Unusual Site‐Selective Doping in Layered Cathode Strengthens Electrostatic Cohesion of Alkali‐Metal Layer for Practicable Sodium‐Ion Full Cell

“…Impressively, compared with the electrochemical properties tested under the mass loading of 2 mg cm −2 , the sodium‐ion full cells with mass loading of 4 and 6 mg cm −2 only show a slightly decreased specific capacity (<4 mAh g −1 ) while the cycling performances are well maintained, which indicates the possibility of its practical application under high mass loading conditions. Compared with recently reported full cell devices based on P2‐Na 0.67 Ni 0.33 Mn 0.67 O 2 layered oxides and other type cathodes, [ 11,22,27,36,52–63 ] as shown in Tables S5 and S6 (Supporting Information), the electrochemical properties of NZNCMO//hard carbon exhibit a balanced advantage considering the simultaneous requirement on the energy density and cycling life, suggesting the great potential of practical applications.…”

Mitigating the Large‐Volume Phase Transition of P2‐Type Cathodes by Synergetic Effect of Multiple Ions for Improved Sodium‐Ion Batteries

“…The effects of dopants on the suppression of P2-O2 phase transformation are further investigated by evaluating the stacking fault energies for Na 23 prefer to occupy an intermediate "Z" intergrowth structure rather than a pure O2 structure instead. It is worth mentioning that the similar calculations are also performed by employing the more elaborate optB86b-vdw+U method where both the van der Waals interactions and on-site strong electron correlation effects (U: Ti (3.2 eV), Mn (3.9 eV), and Ni (6.2 eV)) are included in the methodology.…”

“…[21][22] Although lowering the charge cut-off voltage (below 4.2 V) offers an effective solution, it comes at the cost of a significant decrease in reversible capacity (< 90 mAh g −1 ) and operating voltage (< 3.2 V). [23][24] By contrast, ion substitution/doping strategy shows greater flexibility in balancing cyclic stability and capacity. It has been demonstrated that Li + , Mg 2+ , Cu 2+ , Zn 2+ , Ti 4+ ions can effectively inhibit the P2-O2 phase transition in P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 and improve its cycling performance.…”

Boosting the Redox Kinetics of High‐Voltage P2‐Type Cathode by Radially Oriented {010} Exposed Nanoplates for High‐Power Sodium‐Ion Batteries

“…The obtained large capacity and high voltage of the full cell at high rates ensure that an energy density of ≈165 Wh kg −1 can be maintained even at 10 C in Figure 7f (corresponding to state‐of‐the‐art power density of ≈1650 W kg −1 ). The energy density and power density of this P2‐NaNCMO//hard carbon are compared with those previously reported in literatures, [ 55–64 ] as shown in Figure 7g and Table S2, Supporting Information. This P2‐NaNCMO//hard carbon full cell shows a higher energy density and a higher power density.…”