Inhibiting Sn coarsening to enhance the reversibility of conversion reaction in lithiated SnO₂ anodes by application of super-elastic NiTi films

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• 作者：Renzong Hu^a ; ^b ; Yunpeng Ouyang^a ; Dongchang Chen^b ; Hui Wang^a ; Yu Chen^b ; Min Zhu^a ; ^{memzhu@scut.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Meilin Liu^b ; ^{meilin.liu@mse.gatech.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Tin dioxide ; Conversion reaction ; Sn coarsening ; Super-elasticity ; NiTi alloys
• 刊名：Acta Materialia
• 出版年：2016
• 出版时间：1 May 2016
• 年：2016
• 卷：109
• 期：Complete
• 页码：248-258
• 全文大小：3197 K

文摘

The large capacity loss and low initial Coulombic efficiency (ICE) of a conventional SnO₂-based anode for Li ion batteries are originated largely from the limited reversibility of the conversion reaction associated with the anode. Often, the reversibility of the lithiation/delithiation of SnO₂ (with a high ICE value of ∼82%) declines with Sn coarsening in the Sn/Li₂O mixture during cycling, leading to gradual capacity decay. Here we demonstrate that the application of super-elastic films of NiTi alloy could accommodate the internal stress and volume change of lithiated nano-SnO₂ layer in a tri-layer NiTi/SnO₂/NiTi sandwich anode, effectively suppressing Sn coarsening. This unique electrode configuration has helped to retain the high reversibility of the SnO₂ layer with reversible capacity more than 800 mAh/g (based on SnO₂) for over 300 cycles, demonstrating stable charge capacities of ∼400 mAh/g in the potential ranges of 0.01–1.0 V and 1.0–2.0 V(vs. Li/Li⁺), respectively. Insitu spectroscopic and exsitu diffraction analyses corroborate the highly reversible electrochemical cycling, confirming that the reversibility and cyclability of SnO₂ anodes can be dramatically enhanced by preserving the nanostructure of Sn/Li₂O mixture, which facilitates the reversible conversion reaction.