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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Exploiting the full potential of SiO2 anodes for Li-ion Batteries

Alternative title: Utnytte det fulle potensialet til SiO2-anoder for Li-ion-batterier

Awarded: NOK 8.0 mill.

Li-ion batteries (LIBs) are the dominating technology in portable electronic devices and electric vehicles and are expected to play a more preponderant role in the foreseeable future. However, in view of the growing energy storage needs, major improvements in next-generation LIBs need to be accomplished in order to increase their power and energy density. A primary component of LIBs is the negative electrode, which is commonly made of graphite. Graphite anodes exhibit long-term durability but very limited storage capacity. Alternatively, Silicon (Si) displays storage capacities 10 times higher than graphite, but it suffers from degradation processes that dramatically shortens the cycle life of the anodes and hinders their wide commercialization potential. In this context, naturally abundant Silica (SiO2) has emerged as a promising anode candidate, exhibiting not only high storage capacities, but also good stability after prolonged cycling. However, despite of its great potential, the underlying mechanism of SiO2 reaction towards Li-ions is unknown. Recently, it has been proposed that SiO2 lithiation produces Si domains within a matrix of electrochemically inactive species. As a result, the on-site formed Si would provide high reversible storage capacities, whereas the inactive species would help to reduce degradation processes, therefore extending the cycle life of the anodes. Because of this, a comprehensive investigation of SiO2 reaction towards Li-ions constitutes an essential prerequisite towards the exploitation of the full potential of SiO2 anodes and the development of stable Si anodes. This project aims at using state-of-the-art advanced characterization techniques to reveal the fundamental aspects of SiO2 reaction towards Li, providing an effective knowledge-driven approach to find key enablers for the design and development of high capacity anodes for next-generation LIBs.

Li-ion batteries (LIBs) are the bridge between intermittent renewable energy sources and power demand in multi-scale systems. Thus, considering the importance of renewable energy systems for achieving energy sustainability and mitigating climate change, it is expected that LIBs will play a preponderant role in the foreseeable future. However, major improvements in the design and engineering of electrode materials need to be accomplished in order increase the power and energy density of LIBs. Current negative electrodes of LIBs are made of graphite, which exhibits high stability and long durability, but with very limited storage capacity (372 mAhg-1). In this context, SiO2 has been pinpointed as a promising anode material, exhibiting experimental storage capacities above 1100 mAhg-1, together with stable electrochemical performance after prolonged cycling. Theoretical studies indicate that SiO2 reacts irreversibly with Li, producing electroactive Si domains dispersed in a matrix of inactive species. The on-site produced Si would further react reversibly with Li, being the main contributor to the reversible capacity, whereas the inactive phases would buffer Si volume changes, therefore imparting a higher stability to the anode. However, the reaction mechanism of SiO2 towards Li, as well as the interplay between the reaction products remain unclear. This project aims to set the basis for exploiting the full potential of SiO2 anodes that can outperform current state-of-the-art negative electrodes of LIBs. To this end, we propose to develop a multi-probe methodological approach for a multi-scale characterization of SiO2 anodes using post-mortem and in-situ/operando methods to unveil the fundamental aspects of SiO2 reaction towards Li. The outcomes of this project will provide key enablers for the design and development of high capacity and high stability anodes.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek