ABSTRACT
Self-healing is the capability of materials to repair themselves after the damage has occurred, usually through the interaction between molecules or chains. Physical and chemical processes are applied for the preparation of self-healing systems. There are different approaches for these systems, such as heterogeneous systems, shape memory effects, hydrogen bonding or covalent-bond interaction, diffusion, and flow dynamics. Self-healing mechanisms can occur in particular through heat and light exposure or through reconnection without a direct effect. The applications of these systems display an increasing trend in both the R&D and industry sectors. Moreover, self-healing systems and their energy storage applications are currently gaining great importance. This review aims to provide general information on recent developments in self-healing materials and their battery applications given the critical importance of self-healing systems for lithium-ion batteries (LIBs). In the first part of the review, an introduction about self-healing mechanisms and design strategies for self-healing materials is given. Then, selected important healing materials in the literature for the anodes of LIBs are mentioned in the second part. The results and future perspectives are stated in the conclusion section.
ABSTRACT
Silicon with the properties of high capacity capability, moderate working potential, environmental sensitivity, and existence are the highly promising anode materials for lithium-ion batteries. Silicon anodes have disadvantageous properties and advantages like 300% volume change during lithium insertion and extraction process that can result in capacity fading and a shorter lifetime of the battery. In the literature, different optimizations of Silicon with different nanomaterials or composite materials, in different ratios, and with different binders and different procedures have been studied. The physical mixing of silicon with carbon provides a good performance by combining the high lithium storage capacity of the silicon and the good mechanical and conductive properties of carbon. Binders are one of the other factors affecting the performance of the Si/C anodes. In this study, different ratios of silicon/graphite combinations were tested. The Si/C hybrid material provides an advantageous and efficient use for innovative lithium-ion anodes and available lithium-ion battery technology when the Si/C match performs a suitable combination of two material properties, such as the high lithium storage capacity of silicon and the conductive properties of carbon. This study is aimed to improve the performance of the cell by changing the amount of active material and polymer in the electrode by finding the most appropriate amount of active substance and binder polymer ratio in the electrode. The electrochemical result of the composition, which compensates for the problems caused by the volume expansion of the silicon by using less silicon, showed higher capacitive properties, as it exhibits better adhesion among these compositions with a higher binder ratio. This study resulted in more than 1000 mAh/g specific capacity after 100 cycles at C/3 rate and structural characterization of the samples before and after cycling provided information about the electrode content.
