Preparation And Properties Of High-capacity Sn–C And Sn–Ni Anode Materials For Lithium-ion Batteries

Lithium-ion batteries have shown a great application prospect in small portabledevices, energy storage systems, and electronic devices because of their high energydensity, high voltage and non-pollution. However, the commercial graphite electrodematerials have a relatively lower capacity. As the Sn anode material with a highercapacity, it will produce huge volum changes during the reversible charge anddischarge cycles, which will result in cracking or pulverizing. Cracking andpulverizing are the main causes for the fast fading capacity, which can cause thefailure of electrode. In point of these problems, we considered Sn as the researchsubject of this paper. We started this work from the microstructural aspects andcontents of these anode materials for lithium-ion battery. Preparing micron-nano-sizedmaterials, composites with carbon and alloys with inactive materials, and designinghollow structures were the methods used in this paper. After preparing anode materialswith novel architectures by ball-milling and solvothermal methods, they werecharacterized by XRD, SEM, TEM, Raman, and BET. Their electrochemicalperformances have been evaluated by means of various techniques includinggalvanostatic method, and electrochemical impedance spectroscopy. Futhermore, wehave given a preliminary analysis and evaluation on the comprehensive properties ofthese novel anode materials for lithium-ion batteries. The main contents of this paperare as follows:1. Sn–C composites were successfully prepared by one-step ball-millingapproach. After being compared with the Sn, we concluded that the ball-milled Sn–Ccomposites, which were prepared by milling the Sn and graphite powders, had thebetter comprehensive properties than Sn. The Sn–C compounds displayed a specificcapacity of376mAh g–1after20cycles with fewer irreversible capacity loss, and anincrease in the cycling stability. Just for the smaller size of Sn–C compounds and Cbuffer base, the huge volum changes were buffered to a large degree.2. A general soft-template route for the synthesis of uniform hollow carbonmicrospheres embedded with tiny metal Sn nanocrystals was skillfully developed.After optimizing technical processes, we obtained the best technology conditions of160°C,12h and0.25g of DDA. By calcination process, the final products werecharacterizaed by electrochemical tests. Electrochemical measurments revealed that the carbon-coated hollow anode materials exhibited further improved electrochemicalperformance. The as-obtained Sn–C hollow spheres showed a high and stable specificcapacity of554mAh g–1at a current density of0.25C in30cycles. Due to theirunique hollow structure and excellent carbon-coated layers characteristics, these Sn–Chollow composites displayed an excellent rate capability at0.25C,0.5C,1C,2.5C,5C and15C.3. Ni3Sn2hollow microspheres were skillfully and successfully synthesized via asimple and facile solvothermal approach based on the Ostwald ripening mechanismby combining the active Sn and inactive Ni. After optimizing technical processes, weobtained the best technology conditions of220°C and6h. Their unique hollowstructure and inactive Ni together endowed the Ni3Sn2anode materials excellentelectrochemical performances. Ni3Sn2anode matrials kept a high capacity of about800mAh g–1and a high efficiency of85%at0.1C. Ni3Sn2hollow microspheresshowed an excellent rate capability at0.25C,0.5C,1C,2.5C, and5C, respectively.Among the whole cycles, Ni3Sn2anode could keep a high efficiency of80%exceptthe fist cycle.