Partial lithiation strategies for suppressing degradation of silicon composite electrodes

Effects of external pressure on cycling performance of silicon-based lithium-ion battery: modelling and experimental validation

Controlling the stress state of electrodes during electrochemical cycling can have a positive effect on the cycling performance of lithium-ion battery. In this work, we study the cycling performance of silicon-based lithium-ion half cells under the action of pressure in a range of 0.1 to 0.4 MPa. The cycling performance of the silicon-based lithium-ion half cells increases first with increasing the pressure to 0.2 MPa and then decreases with further increasing the pressure. The analysis of the surface morphologies of cycled electrodes reveals that applying a pressure of 0.2 MPa leads to the formation of fine electrode surface with the least surface cracks after the silicon-based lithium-ion half cells are cycled for 50 times, which supports the dependence of the cycling performance of the lithium-ion half cells on the pressure. The numerical results from the single particle model reveal that applying pressure can tune the stress state in a single electrode particle and reduce the tensile stress. However, the numerical results from the two-particle model point to that applying pressure can introduce tensile stress in the electrode particles due to contact deformation. Suitable pressure applied onto a lithium-ion battery is needed in order to improve the cycling performance of the lithium-ion battery without causing detrimental effects.

Mechanics-based design of lithium-ion batteries: a perspective

From the overall framework of battery development, the battery structures have not received enough attention compared to the chemical components in batteries. The mechanical-electrochemical coupling behavior is a starting point for investigation on battery structures and the subsequent battery design. This perspective systematically reviews the efforts on the mechanics-based design for lithium-ion batteries (LIBs). Two typical types of mechanics-based LIB designs, namely the design at the preparation stage and that at the cycling stage, have been discussed, respectively. The former systemizes the structure design of multiscale battery components from the particle level to the cell level. The latter focuses on the external mechanics-related control, including external pressures and charge-discharge protocols, of in-service LIBs. Moreover, the general problems currently being faced in the mechanics-based LIB design are summarized, followed by the outlook of possible solutions.

Mechanoelectrochemical issues involved in current lithium-ion batteries

The volume change and concurrent stress evolution of electrode materials during the cycling of lithium-ion batteries can cause severe mechanical issues such as the fracture of active materials and electrodes, thus leading to safety issues and capacity fading. Recent years have witnessed a thriving interest to gain a complete understanding of battery electrode materials from the viewpoint of mechanics. This review paper aims at discussing battery electrode materials from a mechanical perspective to provide an overview of the recent innovative efforts in this field. On the one hand, we introduce the mechanical issues of active materials and electrodes in the electrochemical processes, along with a focus on the strategies developed for enhancing the mechanical strength of electrode materials and constructing mechanically robust electrodes. On the other hand, experimental and theoretical studies on the stress-regulated effects on electrochemical processes are discussed to demonstrate the intriguing role of mechanical stress as an enabler in electrochemistry. We also give an outlook on the promising research topics for understanding the material mechanical issues, reinforcing electrode materials and improving battery performance.