High-entropy P2/O3 biphasic cathode materials for wide-temperature rechargeable sodium-ion batteries

Boosting the Ultrastable High-Na-Content P2-type Layered Cathode Materials with Zero-Strain Cation Storage via a Lithium Dual-Site Substitution Approach

“…The corresponding charge–discharge voltage curves at different rates exhibit only minor changes, again highlighting the excellent rate capability (Figure c). As illustrated in Figure d, N 0.9 L 0.1 NMO exhibits superior rate performance, with capacity retentions of 98%, 95%, 92%, and 86% at 1, 3, 5, and 10 C, respectively, in comparison to 0.1 C. This result exceeds those of other P2-type or composite cathode materials. ,,− Electrochemical impedance spectroscopy (EIS) , was conducted on N 0.7 NMO, N 0.9 NMO, and N 0.9 L 0.1 NMO at various temperatures to investigate the interfacial Na-ions transport kinetics . The Nyquist plots of the three samples at various temperatures, along with an equivalent circuit, are presented in Figure S10.…”

“…1,22,36,49−51 It should be noted that N 0.9 L 0.1 NMO achieves an impressive energy density of around 250 Wh kg −1 in a full cell operating at 10 C (1300 mA g −1 ), surpassing the reported value, i.e., 218 Wh kg −1 at 800 mA g −1 . 1 The long-term cycling stabilities of the three cathodes were further assessed in a full cell at 2 C within the range 2.0−4.0 V. Impressively, N 0.9 L 0.1 NMO exhibits a high capacity retention of 73% after 1000 cycles, as depicted in Figure 5g. This retention value surpasses that of N 0.7 NMO (36%) and N 0.9 NMO (51%) by a considerable margin.…”

“…Sodium ion batteries (SIBs) have been regarded as a prospective alternative to lithium-ion batteries (LIBs) owing to the merits of sodium abundance in the Earth’s crust and the low price of sodium resources. − Exploiting long-life cathode materials with superior reliability plays an utmost role in the commercial application of SIBs. Among most candidates, layered oxides Na x TMO 2 (TM represents transition metals) have gained considerable attention due to high theoretical specific capacity, feasible synthesis, and environmental benignity. − Considering the coordination of the Na-ions [i.e., octahedral (O) or prismatic (P)] and the number of the O-ion layer or TMO 6 layer in a one-unit cell (typically, 1–3), Na x TMO 2 cathode materials are categorized into P2, P3, O2, and O3 phases. ,,, P2-type and O3-type layered oxides are better suited to functioning as cathode materials for SIBs.…”

Sustainable Enhanced Sodium-Ion Storage at Subzero Temperature with LiF Integration

“…However, all these layered structures suffer from multiple phase transitions and decreased capacity during long-term cycling. , Consequently, it is highly desired to develop cathodes with optimized composition for improved cycle life and higher capacities . Several techniques like the integration of multiple phases and tuning the metal composition or incorporation of structure-stabilizing elements had already been proved to be very effective in improving the electrochemical performance. − For instance, Feng et al. explored the performance of a P2/O3 composite cathode (Na 0.8 Li 0.13 Ni 0.2 Fe 0.1 Mn 0.57 O 2 ), which delivered a capacity of 133.4 mAh g –1 at a high rate of 1C and a capacity retention of 88.6% after 100 cycles .…”

Injecting Excess Na into a P2-Type Layered Oxide Cathode to Achieve Presodiation in a Na-Ion Full Cell

“…Na-ion batteries (NIBs) have attracted significant attention owing to their great promise in large-scale storage systems because of the low cost and wide distribution of sodium on Earth. − Recently, significant advancements have been made in the core material systems and key battery technologies, but the initial active Na loss has always limited the further improvement of the energy density of NIBs. ,− Even though hard carbon (HC) is a promising anode material candidate for NIBs, it suffers from a low initial Coulombic efficiency (∼75%) due to solid electrolyte interphase (SEI) layer formation on its surface, , which causes a significant loss of active Na and appreciably decreases the specific capacity and energy density of the full cell. On the cathode side, on the contrary, P2-type layered oxides are attractive cathode materials because of their excellent cycling stability and rate capability. − However, inherent Na deficiency, with only approximately two-thirds of Na present per formula unit, constrains their capacity performance upon application to full cells, as the cathode is the sole source of active Na in the full cell. , In this case, the lack of active Na becomes even more severe when a HC anode and a Na-deficient P2-type cathode are employed in a full cell.…”