Engineering Approaches to Dendrite Prevention in Lithium Anode Based Batteries

Abstract

INTRODUCTION Lithium has the potential of being the pre-eminent negative electrode in energy storage systems given its small ionic radius, high charge/mass ratio [reflected in a very negative reduction potential (-3.04 V wrt SHE)] and high theoretical capacity (~3862 mAh/g). The shuttling attribute of Li+ is also rivalled by hydronium ions though limited by aqueous potential window. The transition to lithium anode based systems however, has primarily been stymied by safety concerns owing to the fact that lithium forms dendrites in the process of plating/de-plating. Dendrite formation is a well-known metallurgical phenomenon occurring as a result of several energy minimization processes including preferential growth during crystallization Dendrite formation and growth in lithium are however not well-understood owing to the additional factor of solid-electrolyte interphase (SEI) formation(1).The control of lithium dendrite formation is a veritable challenge that could very well make universal adoption of battery systems possible for both stationary and mobile applications. A number of approaches have previously been proposed for the same with varying degrees of success at addressing the issue (2-7). A common strategy involves the use of polymeric/carbon coatings as a method to address fracture. The coating either aids in preventing dendrite growth by allowing for directed growth or acts as a mechanical barrier to rupture and thus cell-failure. Such an approach however lacks scalability given that there is the associated problem of volumetric change especially in thicker lithium electrodes.In this work, a multi-pronged approach has been taken to solve the issue of dendrite formation in thick lithium electrode involving the use of composite lithium anodes (CLAs) suitable for bearing the significant volumetric change associated with lithium plating-deplating while ensuring prevention of dendrite formation. The nature of the composite lithium anodes will be discussed along with electrochemical stability and voltage hysteresis behavior. Figure 1 shows the dendrite-free SEM images of CLA electrodes as evidence of the improved cycling characteristic obtained for composite current collector based lithium electrodes in a half-cell configuration.