posted on 2024-02-21, 17:04authored byYixu Zhang, Jiarui Chen, Ruijuan Wang, Lei Wu, Wenhao Song, Shuang Cao, Yongqiang Shen, Xiaoyan Zhang, Xianyou Wang
P2-type
Fe–Mn-based oxides offer excellent discharge specific
capacity and are as affordable as typical layered oxide cathode materials
for sodium-ion batteries (SIBs). After Cu modification, though they
can improve the cycling performance and air stability, the discharge
specific capacity will be reduced. Considering the complementary nature
of biphasic phases in electrochemistry, hybridizing P2/O3 hybrid phases
can enhance both the storage performance of the battery and specific
capacity. Herein, a hybrid phase composite with high capacity and
good cycle performance is deliberately designed and successfully prepared
by controlling the amount of Mg doping in the layered oxide. It has
been found that the introduction of Mg can activate anion redox in
the oxide layer, resulting in a significant increase in the specific
discharge capacity of the material. Meanwhile, the dual-phase structure
can produce an interlocking effect, thus effectively alleviating structure
strain. The degradation of cycling performance caused by structural
damage during the high-voltage charging and discharging process is
clearly mitigated. The results show that the specific discharge capacity
of Na0.67Cu0.2Mg0.1Fe0.2Mn0.5O2 is as high as 212.0 mAh g–1 at 0.1C rate and 186.2 mAh g–1 at 0.2C rate. After
80 cycles, the capacity can still maintain 88.1%. Moreover, the capacity
and cycle performance as well as the stability can still remain stable
even in the high-voltage window. Therefore, this work offers an insightful
exploration for the development of composite cathode materials for
SIBs.