This study investigates the viability of using a Na-ion battery with a tin(Sn) anode to mitigate the vulnerability caused by volume changes during discharge and charge cycling. In general, the volume changes of carbon material do not cause any instability during intercalation into its layer structure. Sn has a high theoretical capacity of 847 mAh g−1. However, it expands dramatically in the discharge process by alloying Na-Sn, placing the electrode under massive internal stress, and particularly straining the binder over the elastic limit. The repeating strain results in loss of active material and its electric contact, as well as capacity decrease. This paper expands the scope of fabrication of Na-ion batteries with Sn by fabricating the binder as an auxetic structure with a unique feature: a negative Poisson ratio (NPR), which increases the resistance to internal stress in the Na-Sn alloying/de-alloying processes. Electrochemical tests and micrograph images of auxetic and common binders are used to compare dimensional and structural differences. Results show that the capacity of an auxetic-structured Sn electrode is much larger than that of a Sn electrode with a common-structured binder. Furthermore, using an auxetic structured Sn electrode, stability in discharge and charge cycling is obtained.

본 연구는 음의 포아송비 거동을 가지는 격자체의 구조부재 보강재로의 적용이 가능한지에 대한 검토를 수행하였다. 콘크리트를 포함한 일반적인 재료는 외부 하중의 작용 시 양의 포아송비 거동을 가진다. 이러한 콘크리트의 역학적 거동을 음의 포아송비 특성을 가지는 금 속 격자체가 구속함으로써 콘크리트의 강성을 증대시킬 수 있음을 이론적으로 확인하였다. 또한 실제 건설산업에 적용이 가능한 수준의 음의 포아송비 거동을 가지는 격자체의 형식을 제시, 역학적 거동 특성을 수치 해석적으로 검토하였다.

This study examined the effects of the embedded auxetic grating structures by design on numerical analysis. Compressive tests were performed and the results showed the effectiveness of auxetic grating structures for the enhancements of stiffness.

This study examined the effects of the embedded auxetic grating structures by design on numerical analysis. Compressive tests were performed and the results showed the effectiveness of auxetic grating structures for the enhancements of stiffness.