摘要
钠离子电池(SIBs)被认为是一种有前途的大规模储能技术,O3型层状过渡金属氧化物因其优异的比容量成为最有前景的SIBs正极材料之一。然而,层状过渡金属氧化物在充电至高电压时稳定性较差,影响材料的实际应用。通过SEM、TEM以及原位XRD技术对O3‐NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)材料进行了表征,并对其电化学性能进行测试,探究了该材料微观结构与稳定性的内在关系。结果表明,该材料的相变导致Na^(+)扩散系数降低,在4.1 V以上的高电压时发生的不可逆P3-O3´相变使Na^(+)扩散系数降低至少5个数量级,具体表现为内阻显著增加;O3´相在放电过程中诱导P´3相的出现,使材料偏离充电时经历的路径,降低材料的循环稳定性。
Sodium‐ion batteries(SIBs)have garnered considerable attention as a viable option for large‐scale energy storage,with O3‐type layered transition metal oxides identified as one of the most promising cathode materials due to their superior specific capacity.However,the stability of these materials at elevated voltages remains a critical challenge,hindering their broader application.In this study,O3‐NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)was systematically characterized using scanning electron microscopy(SEM),transmission electron microscopy(TEM),and in‐situ X‐ray diffraction(XRD)to elucidate the relationship between microstructural evolution and electrochemical stability.The results reveal that phase transitions significantly impair Na⁺diffusion kinetics.Notably,the irreversible P3-O3´phase transition at high voltages above 4.1 V results in a reduction of the Na^(+)diffusion coefficient by at least five orders of magnitude,which is reflected by a substantial increase in internal resistance.Moreover,the O3´phase emerging during discharge triggers the formation of the P´3 phase,deviating it from the electrochemical pathway established during charging and thereby severely compromising the material’s cycling stability.
作者
张博杨
滕彦梅
ZHANG Boyang;TENG Yanmei(Jiangsu Highstar Battery Manufacturing Co.,Ltd.,Qidong Jiangsu 226200,China;Shanghai PRET Composites Co.,Ltd.,Shanghai 201707,China)
出处
《石油化工高等学校学报》
CAS
2024年第6期52-61,共10页
Journal of Petrochemical Universities
基金
2023年上海市“超级博士后”激励计划资助(2023039)
国家资助博士后研究人员计划项目(GZC20233448)。
关键词
钠离子电池
层状氧化物
高电压
稳定性
相变
Sodium ion battery
Layered oxide
High voltage
Stability
Phase transition
