Durable Sno-Lto Composite Anode for Lithium Ion Batteries

Anode materials play a pivotal role for high power and high power density lithium ion batteries applications. ¹. Graphite was the dominant materials of choice, but still fall short of the goal owing to low rate-capability and specific capacity (372 mAh.g^-1). Among other electrochemically active materials, Tin monoxide (SnO) appears promising to replace graphite and is widely explored due to its high specific capacity (875 mAh.g^-1). However it suffered from pulverization ² problem and hampered its commercial implementation. In this study we have developed a novel composite anode material that combined two types of lithium ion insertion and exertion mechanisms with the purpose to reduce pulverization, to improve rate capability and to raise cycling performance. SnO is alloying/de-alloying system, which possess higher specific capability and electrochemical activity. On the other hand, Li₄Ti₅O₁₂ (LTO) is an intercalation/de-intercalation system, which shows unique rate-capability and zero-strain ability ³ . Combining these two features characteristic of the two materials we are able to stabilize the huge volume change of SnO. Pure SnO and the composite powder with SnO/LTO of 75/25, 50/50 and 25/75 wt% were successfully synthesized by sol-gel method. The decrease of capacity with increasing C-Rate was found to be slower that of generic SnO in SnO-LTO(75/25) composite powders, and a high discharge capacity of 466.2 mAh.g^-1 at 1Crate was observed.  Note that this is higher than that in commercial graphite anode materials. The presence of LTO appears to improve simultaneously the rate capability and cycle life through stabilizing the structure of whole active material, and the synergistic mechanism will be discussed.

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