Silicon-based Batteries: Periodic Nanostructuration for enhanced properties

提高锂离子电池负极的硅含量是一个目标，也是一个挑战。硅的容量是石墨的十倍，但耐久性是瓶颈。事实上，在锂化过程中，合金反应会引起300%的体积变化，产生显著的应力和电极的快速降解。对于使用纳米结构硅来提高锂离子电池阳极的耐久性，人们达成了共识。然而，成绩的改善是不平衡的，造成这些差异的原因还没有完全了解。我们的假设是，纳米结构需要是有组织的，甚至更好，是周期性的。提出的研究计划旨在提高锂离子电池硅基电极的性能，其电极设计灵感来自具有特殊机械性能的细胞材料的拓扑结构。因此，该方案的总体思路是通过组织硅纳米结构的孔隙度来优化其力学性能。该策略包括：1)采用不同的合成方法，设计从有序的、周期性的介孔硅到三周期最小表面（TPMS）的多孔周期性硅；ii)建模、表征和优化其机械性能；iii)测试电化学性能并表征我们优化结构的电化学诱导效应。总体目标是验证我们的工作假设，并提供一个概念证明，这肯定会引发大量的研究和开发活动，以生产更好的结构多孔结构，并通过遵循我们的指导方针和路线图，将锂离子电池复合阳极的Si含量提高到最大可能的值。10名HQPs（3名博士，2名硕士，5名实习生）将在能源材料领域的前沿研究课题上接受培训。

Increasing the silicon content in Li-ion battery anodes is a target and a challenge. The capacity of Si is ten times higher than in graphite but the durability is a bottleneck. Indeed, during lithiation, the alloying reactions induce volume variations of the order of 300%, generating significant stress and rapid degradation of the electrode. There is a consensus on the interest of using nanostructured silicon for increasing the durability of the Li-ion battery anodes. Nevertheless, improvement of performance has been uneven and the reasons for these discrepancies have not been fully apprehended. Our hypothesis is that the nanostructuration needs to be organized and, even better, periodic. The proposed research program aims at boosting the performance of silicon-based electrodes for Li-ion batteries by electrodes by a design of materials inspired by the topology of cellular materials with exceptional mechanical properties. Therefore, the general idea of this program is to optimize the mechanical properties by organizing the porosity of silicon nanostructures. The strategy consists of i)Designing porous periodic Si with increasing complexity, from organized, periodic mesoporous silicon to Triply Periodic Minimal Surfaces (TPMS) using different synthesis methods; ii)Modelling, characterizing and optimizing their mechanical properties; iii)Testing the electrochemical properties and characterizing the electrochemically-induced effects on our optimized structures. The overall objective is validating our working hypothesis and delivering a proof of concept that will definitely trigger a larger amount of research and development activities to produce better structured porous architectures and increase the Si content of a composite anode for Li-ion batteries to a maximum possible value, by following our guidelines and roadmap. Ten HQPs (3 PhDs, 2 Mscs, 5 interns) will benefit from training on a cutting-edge research topic in the field of energy materials field.