焙烧条件对Na_(3)V_(2)(PO_(4))_(3)/C的制备及储锌性能影响

Effect of calcination conditions on preparation and zinc storage performance of Na_(3)V_(2)(PO_(4))_(3)/C

采用喷雾干燥法合成了Na_(3)V_(2)(PO_(4))_(3)(NVP)前驱体,然后经过高温煅烧得到水系锌离子电池正极复合材料Na_(3)V_(2)(PO_(4))_(3)/C(NVP/C),考察了煅烧温度和煅烧时间对NVP/C性能的影响。通过XRD、SEM和BET对样品结构和形貌进行了表征,通过循环伏安和充放电测试了样品的电化学性能。结果表明,不同煅烧温度和煅烧时间制备样品均为纯相的NVP/C,且并没有改变NVP/C的晶体结构;煅烧温度过高或煅烧时间过长会导致晶粒尺寸增大,性能迅速衰减。NVP/C制备最佳条件为煅烧温度700℃、煅烧时间8 h,在该条件下所制备的NVP/C(记为NVP/C-700-8)形貌更为规整,结晶性良好,具有较小的阻抗以及更好的离子扩散能力,进而表现出最佳的电化学性能。在0.1 A/g电流密度下表现出最佳的放电比容量(122.4 mA·h/g)。在1.0 A/g电流密度下经过200圈循环后放电比容量仍高达103.9 mA·h/g。

Cathode composite material Na_(3)V_(2)(PO_(4))_(3)/C(NVP/C)in aqueous Zn-ion batteries was synthesized via high-temperature calcination of precursor Na_(3)V_(2)(PO_(4))_(3)(NVP)prepared by spray drying method,and the influence of calcination temperature and time on the performance of NVP/C were then investigated.The structure and morphology of NVP/C were characterized by XRD,SEM and BET,while the electrochemical activity of samples obtained were analyzed by cyclic voltammetry and charge and discharge test.The results showed that pure NVP/C were obtained regardless calcination temperature and time with no difference in its crystal structure as well.However,higher calcination temperature or longer calcination time could lead to increase in particle size and rapid activity decline.Therefore,calcination temperature 700℃ and calcination time 8 h were determined as the optimal NVP/C preparation conditions,under which the sample(named as NVP/C-700-8)displayed more regular morphology,good crystallinity,lower impedance and better ion diffusion ability,thus exhibited the best electrochemical performance with a discharge specific capacity of 122.4 mA·h/g at 0.1 A/g.Moreover,the discharge specific capacity still reached 103.9 mA·h/g after 200 cycles at 1.0 A/g.