Lithium-Doping Stabilized High-Performance P2–Na_0.66Li_0.18Fe_0.12Mn_0.7O₂ Cathode for Sodium Ion Batteries

Abstract

While sodium-ion batteries (SIBs) hold great promise for large-scale electric energy storage and low speed electric vehicles, the poor capacity retention of the cathode is one of the bottlenecks in the development of SIBs. Following a strategy of using lithium doping in the transition-metal layer to stabilize the desodiated structure, we have designed and successfully synthesized a novel layered oxide cathode P2–Na0.66Li0.18Fe0.12Mn0.7O2, which demonstrated a high capacity of 190 mAh g–1 and a remarkably high capacity retention of ∼87% after 80 cycles within a wide voltage range of 1.5–4.5 V. The outstanding stability is attributed to the reversible migration of lithium during cycling and the elimination of the detrimental P2–O2 phase transition, revealed by ex situ and in situ X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy.

Realizing Complete Solid‐Solution Reaction in High Sodium Content P2‐Type Cathode for High‐Performance Sodium‐Ion Batteries

“…One is the edge‐sharing site (Na e ), and the other is face sharing with adjacent oxide layers (Na f ). A preferred occupancy at Na e sites is observed because of lower electrostatic repulsion at this position, which is commonly observed in P2‐type compounds . The specific crystallographic data of P2‐NNMO and P2‐NLNMO are listed in Tables S2 and S3, respectively.…”

Li‐doping stabilized P2‐Li 0.2 Na 1.0 Mn 0.8 O 2 sodium ion cathode with oxygen redox activity

“…To suppress the over extraction of Na atoms contributing to crystal distortion in Na 1.2 Mn 0.8 O 2 , we substitute 0.2 M Na atoms with Li atoms inspired by literatures . P2‐Li 0.2 Na 1.0 Mn 0.8 O 2 was synthesized through conventional solid‐state reaction among Li 2 CO 3 , Na 2 CO 3 , and MnCO 3 mixture.…”

“…Methods such as doping various transitional metal and alkaline metal (AM) have been proposed to restrain the P2‐O2 transition . Chen et al have shown that substituting lithium in the manganese position is a bright approach cause that the clustering between Mn 4+ and the Li + can effectively stabilize the adjacent oxygen ions and therefore restraining the P2‐O2 gliding . Lithium doping was also previously testified to be quite valid on P2‐Na 0.85 Li 0.17 Ni 0.21 Mn 0.64 O 2 , Na x [Li y Ni z Mn 1‐y‐z ]O 2 , P2‐Na 0.80 [Li 0.12 Ni 0.22 Mn 0.66 ]O 2 , and P2‐O3 Na 2/3 Li 0.18 Mn 0.8 Fe 0.2 O 2 cathodes …”

“…[23][24][25][26][27][28] Chen et al have shown that substituting lithium in the manganese position is a bright approach cause that the clustering between Mn 4+ and the Li + can effectively stabilize the adjacent oxygen ions and therefore restraining the P2-O2 gliding. 29 Lithium doping was also previously testified to be quite valid on P2-Na 0. 85 31 In this work, a new compound P2-Li 0.2 Na 1.0 Mn 0.8 O 2 was designed, merely replacing a portion of Na in compound P2-Na 1.2 Mn 0.8 O 2 , with Li atoms substituting Na atoms in the transitional as well as AM layer with the rationale that it may help keep partial Na standing in the lattice during cycling, which superiorly improve the cycling stability from irreversibility to reversible 100 cycles.…”

P2‐Na0.67AlxMn1−xO2: Cost‐Effective, Stable and High‐Rate Sodium Electrodes by Suppressing Phase Transitions and Enhancing Sodium Cation Mobility

“…As a result, the requirement for the discharge rates of sodium‐ion batteries is much higher/faster than charge. Therefore, as well as the previous researches, the rate capabilities are tested by charging at low current and discharging at various currents. Specifically, the cells were charged at a constant current density of 24 mA g −1 and discharged at 12–4800 mA g −1 , respectively.…”