强耦合氧化钼氮碳复合材料的制备及其锂离子存储性能研究

Atomic Mo-NC-sourced robust MoO_(3)/C nanocomposite for highperformance Li-ion storage

氧化钼(MoO_(3))是一种具有吸引力的锂离子电池(LIBs)负极材料;然而,其导电性低、锂化后体积膨胀大、锂离子扩散动力学缓慢等特点严重限制了其实际应用.本文中,我们利用高量Mo/N掺杂的碳前驱材料合成了超细的MoO_(3)纳米颗粒(NPs,10–15 nm),所合成的MoO_(3)NPs被限制在原位生成的N掺杂碳网络结构中.这种设计既促进了快速的电子传导,又缩短了锂离子扩散路径;同时,MoO_(3)表面丰富的氮物种和氧缺陷有助于降低锂离子的吸附能垒,这些共同支持了MoO_(3)NPs在高电流倍率下耐久储锂性能的提升.值得注意的是,所获得的NCMoO_(3)纳米复合材料表现出1362 mA h g^(−1)(0.1 A g^(−1))的较高容量,并在10.0 A g^(−1)时保持394 mA h g^(−1)的可逆容量.全电池测试表明:在大倍率5 C下,LiFePO_(4)//NC-MoO_(3)-400电池仍可以输出81 mA h g^(−1)的比容量.我们的工作有望启发其他嵌入导电碳网络的过渡金属氧化物的设计合成及其在LIBs中的实际应用.

Molybdenum oxide(MoO_(3))is an attractive anode material for lithium-ion batteries(LIBs);however,its low electrical conductivity,large volume expansion after lithiation,and slow Li-ion diffusion kinetics severely limit its practical applications.Here,ultrafine MoO_(3)nanoparticles(NPs)(10–15 nm)are synthesized from heavily Mo/N-doped carbonaceous precursors,resulting in MoO_(3)NPs confined in an N-doped carbon network.This design allows fast electron conduction and short Li-ion diffusion paths;meanwhile,abundant N species and O vacancies on the MoO_(3)surface lower the Li-ion adsorption barrier and together contribute to the durable Li-ion storage at high current rates.Notably,the obtained nanocomposite NC-MoO_(3)exhibits a high capacity of 1362 mA h g^(−1)(0.1 A g^(−1))and maintains a reversible capacity of 394 mA h g^(−1)at 10.0 A g^(−1).A coin-type full LiFePO_(4)//NCMoO_(3)-400 cell obtains a large specific capacity of 81 mA h g^(−1)at 5 C.Our work inspires the design and confinement synthesis of other transition metal oxides embedded in conducting carbon networks for practical LIB applications.