Synthesis of Nickel Phosphide/Nitrogen Phosphorus Co-Doped Carbon and Its Application in Lithium Ion Batteries

以离子液体为碳源和氮源、次亚磷酸钠为磷源、乙酸镍为镍源,一步法制备了磷化镍/氮磷共掺杂碳(Ni2P/NPC)复合材料。SEM、TEM等检测结果表明Ni2P纳米颗粒在N、P共掺杂碳骨架上均匀分布。将所制备Ni2P/NPC作为锂离子电池负极材料时,Ni2P/NPC电极在0.1、0.5、1、3和5 A·g-1电流密度下的放电比容量分别为377.7、 294.1、 265.4、211.7和187.5 mAh·g-1。当电流密度重新回到0.1 A·g-1,放电比容量为368.1 mAh·g-1。电极结构在大倍率下可以保持稳定,表现出优异的倍率性能。在0.5 A·g-1的电流密度下经200次循环后放电比容量维持在301.8 mAh·g-1,容量保持率为80.7%,CV曲线证实Ni2P/NPC在储锂过程中是由扩散过程和电容行为共同控制。In recent years, the nickel-based phosphide has drawn great attention because of its low intercalation/deintercalation platform and lower polarization compared to sulfides and oxides as anodes for next-generation high-energy lithium-ion batteries. The Ni2P anode can deliver high theoretical specific capacity of 542 mAh·g-1, but it subject to a conversion reaction mechanism, which make them unsuitable for commercial applications. The agglomeration of Ni2P nanoparticles during material fabrication and the structural deterioration of electrode associated with large volume change during charge-discharge process lead to poor cycle stability and low utilization of active materials. Meanwhile, the low intrinsic conductivity of Ni2P is also sluggish electrochemical reaction kinetics. Herein, we design a facile and viable approach to synthesize Ni2P/NPC composites with a stable structure to address these issues. This new approach entails synthesis of Ni2P/NPC by a N and P co-doped carbon framework with ionic liquids assistance during synthesis. This stable composite structure can serve as anode material of lithium ion batteries with good electrochemical performance. The Ni2P/NPC composites were prepared by one-step method using ionic liquids as carbon and nitrogen sources, while sodium hypophosphite and nickel acetate as phosphorus and nickel sources, respectively. The results of SEM and TEM show that Ni2P nanoparticles were uniformly distributed on the N and P co-doped carbon framework. When the Ni2P/NPC composite was used as an anode material of lithium ion batteries, the discharge specific capacities were 377.7, 294.1, 265.4, 211.7 and 187.5 mAh·g-1 at 0.1, 0.5, 1, 3 and 5 A·g-1, respectively. When the current density returned to 0.1 A·g-1, the discharge specific capacity reached 368.1 mAh·g-1. The Ni2P/NPC structure could be kept stable at high rate, showing excellent rate performance. The fabricated Ni2P/NPC anode delivered the discharge specific capacity of 301.8 mAh·g-1 with the capacity retention of 80.7% after 200 cycles at 0.5 A·g-1. Finally, CV curves confirmed that the lithium storage of Ni2P/NPC colud be controlled by diffusion process and capacitance behavior.国家自然科学基金项目(51404124);省部共建有色金属先进加工与再利用国家重点实验室开放基金(SKLAB02019015)通讯作者:蒙延双E-mail:mengyanshuang@163.comContact:Yan-ShuangMengE-mail:mengyanshuang@163.com兰州理工大学材料科学与工程学院,甘肃 兰州 730000School of Materials Science and Engineering, Lanzhou University of Technology,Lanzhou 730000, Gansu Chin