结构稳定的高比容量高熵型层状氧化物钠离子电池正极材料研究

Mechanochemical Process on Layered Compounds MoO_(3)and Graphite to Construct Heterostructure Composites and its Lithium Storage Performance

依据不同金属离子在钠离子电池层状氧化物储电过程中的作用特点,选择了Ni、Mn、Fe、Cu、Ti 3个过渡金属元素以一定的组成比例采用球磨和高温固相烧结结合的方法制备了新型无Co高熵层状氧化物正极材料NaNi_(0.3)Cu_(0.1)Fe_(0.1)Mn_(0.44)Ti_(0.06)O_(2).合理的元素组合和组成使得具有高熵特征的材料在充放电过程中生成的Na-空位规则度较低,相转移可逆性高,从而表现出理想的储电性能.其在较高的电流密度(1 C)下,依然能提供较多的钠离子储存位点,且结构稳定性较高,放电比容量为123.6 mAh/g.循环200圈后,比容量依旧保持在104.6 mAh/g,保持率为84.6%.

This paper investigates the distinct funtional characteristics of different metal ions in the electrochemical energy storage process of layered sodium-ion batteries.Ni,Mn,Fe,Cu,and Ti were selected,and their compositions were adjusted to fabricate a novel cobalt-free high-entropy layered oxide cathode material,NaNi_(0.3)Cu_(0.1)Fe_(0.1)Mn_(0.44)Ti_(0.06)O_(2),by using a combination of ball milling and high-temperature solid-state sintering methods.The rational combination and composition of elements enabled the high-entropy sample to exhibit low Na-vacancy ordering and high phase transition reversibility during charge-discharge processes,thereby demonstrating desirable electro-chemical performance.Under a relatively higher current density of 1 C,the specific capacity of the hybrid material remained stable at 123.6 mAh/g,indicating a stable structure and providing more Na-ion storage sites.Even after 200 cycles,the specific capacity remained at 104.6 mAh/g,with a capacity retention rate of 84.6%.