Research And Application Of The Advanced Li-insertion Materials

Research and application of the advanced Li-insertion materialsLiu Yu (Materials Physics and Chemicals) Directed by Yang Jun and Xie JinyingRechargeable lithium ion batteries have attracted worldwide attention, because their application can achieve high energy density. The intentions of this work mainly focus on looking for advanced insertion materials and investigating whether they can use as anode in the rechargeable Li-ion batteries.The alloy/carbon composites have been prepared and investigated in the liquid electrolytes. Moreover the electrochemical behaviors of the composite anode and the Li-ion batteries based on the solid PEO electrolytes have been studied.The structure and morphology profiles of the alloy/carbon composites have been confirmed by XRD and SEM technology. Results reveal that sub-micro Sn based alloy particles homogenously deposite on the surface and in the pore of the carbon matrix. The electrochemical cycling tests show that the composites demonstrate large reversible capacity and enhanced mechanical stability for Li-insertion. The capacity retention at the 5011' cycle is 91% for Sn/CMS composite containing 22% tin, versus 428 mAh g"1 at the first cycle. The electrochemical behaviors of the alloy/carbon materials highly depend on the compositions and the contents of deposited alloy particles and the categories of carbon matrix.Due to the volume effects of the metallic hosts caused by Li-insertion, the morphology stability of the composite electrode and the interfacial compatibility between the composite electrode and the electrolytes dominate the cycling performance in the solid PEO electrolytes. The cycliability of the anode can be significantly improved by optimizing of the electrode composition, the electrode preparation, the electrode design, the operating temperature and the working condition. On the other hand,Li2.eCoo.4N displays high sensitivity in the solid PEO electrolytes. The solid PEO cells consisting of the LiNio.gCoo.202 cathode and the Li2.6Coo.4N-SnSb anode deliver high reliance and large special energy density as 110 Wh Kg"1. The electrochemical properties of the composites materiles based on nano-size SiO demonstrate strong reliance upon the interfacial compatibility between the anode and the electrolytes. It is believed that suitable active components and the enhanced mechanical stability of insertion hosts, as well as increased interfacial compatibility between anode and electrolytes, are highly favor for improving the cycling performance of the composite anode in the solid PEO electrolytes at the elevated temperature.