提高锂离子电池负极的电化学储锂容量和倍率性能—三维互连碳管-NiO-SnO_(2)网格膜

Enhancing electrochemical energy storage capacity and rate performance of the anode with a 3D interconnected carbon tube-NiO-SnO_(2) composite scaffold

二氧化锡(SnO_(2))具有高的理论比容量,有望作为下一代锂离子电池负极材料.然而,Sn向SnO_(2)的不可逆转化以及充放电过程中巨大的体积变化限制了其实际的应用.本文基于三维互连多孔氧化铝模板,设计合成了一种由内腔同时填充NiO和SnO_(2)纳米颗粒的碳管基元相互连接组成的三维碳管网格膜,可以直接作为自支撑的高性能锂离子电池负极.该复合框架利用了NiO和SnO_(2)纳米颗粒的协同作用,不仅能够促进Sn向SnO_(2)的可逆转变,提高首次库伦效率,而且还可以缓释充放电过程中SnO_(2)剧烈的体积变化.此外,相互连接的三维碳管框架可以负载大量NiO和SnO_(2)纳米颗粒,缩短Li+的扩散距离,并作为快速的电子传输通道.因此,这种独特的结构赋予了该电极超高的储锂容量和倍率性能在1 A g^(-1)循环200次后,比容量达到928.5 mA h g^(-1),并且在4 A g^(-1)的高电流密度下仍然具有633.5 mA h g^(-1)的比容量.总之,这种独特的一体化结构在锂离子电池等储能领域具有广阔的应用前景.

Tin dioxide(SnO_(2))possesses great potential as an anode material for lithium-ion batteries(LIBs)owing to its high theoretical specific capacity.However,the irreversible conversion of Sn to SnO_(2) and enormous volume variation during the charge/discharge process limit the battery energy storage performance.In this study,ultrafine NiO and SnO_(2) nanoparticles(NPs)decorated on a three-dimensionally(3D)interconnected and structurally integrated carbon tube(CT)scaffold(NiO/SnO_(2)-NPs@3D-CT)is developed as an anode,eliminating any inactive component in the electrode.The NiO not only contributes to the capacity but also undergoes reduction to Ni during the lithiation process,which catalyzes Li2O decomposition and facilitates the reversible conversion of Sn to SnO_(2).Additionally,the open space of the 3D scaffold can host a large number of NiO/SnO_(2) NPs and results in a short diffusion distance of Li+between the electrolyte and the Li+host.The interconnected 3D-CT network serves as a fast electron transport channel.Consequently,the unique structure endows the anode with high Li-ion storage capacity(928.5 mA h g^(−1) at a current density of 1 A g^(−1) after 200 cycles)and superior high-rate performance;for instance,a reversible capacity of 633.5 mA h g^(−1) can be achieved even at a current density of 4 A g^(−1).We believe that the unique,integrated 3D structure holds great promise as an anode for LIBs and that its applications can be further extended to other fields.