Silicon-based Batteries: Periodic Nanostructuration for enhanced properties

增加锂离子电池正极中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，但耐久性是一个瓶颈。事实上，在锂化过程中，合金化反应引起300%量级的体积变化，产生显著的应力和电极的快速降解。人们对使用纳米结构硅来提高锂离子电池阳极的耐用性达成了共识。然而，业绩的改善是不均衡的，这些差异的原因还没有得到充分的理解。我们的假设是，纳米结构需要被组织起来，更好的是，周期性的。拟议的研究计划旨在通过电极来提高锂离子电池硅基电极的性能，方法是设计一种受具有特殊机械性能的蜂窝材料拓扑结构启发的材料。因此，该计划的总体思路是通过组织硅纳米结构的孔隙率来优化机械性能。该策略包括：i)使用不同的合成方法设计复杂的多孔周期性硅，从有序的周期性介孔硅到三重周期极小表面(TPMS)；ii)建模、表征和优化其机械性能；iii)测试其电化学性质，并表征电化学诱导对优化结构的影响。总体目标是验证我们的工作假设，并提供概念验证，通过遵循我们的指导方针和路线图，肯定会引发更多的研究和开发活动，以生产更好的结构多孔结构，并将锂离子电池复合负极的硅含量提高到最大可能值。10名HQP(3名博士、2名MSCS、5名实习生)将受益于能源材料领域前沿研究课题的培训。

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.