Investigating the effect of electrode structuring on fast charging applications

Abstract

Global warming, increase of the greenhouse gas emissions and scarcity of conventional energy sources are some of the most fundamental challenges for the present and future generations [1]. As a consequence the increasing share of EVs in the transport sector has received considerable attention, leading to an exponential growth of the total EVs production in the last few years [2]. The need for outstanding energy density, high power density and long life-time has made Li-ion batteries the dominating technology in the past decade. However, the number of EVs is still not comparable to the huge number of sold cars with conventional combustion technology [2]: In fact, many challenges for Li-ions batteries need to be solved before meeting the requirements of the automotive industry. Main issues are the energy density, cost, safety and fast charging capability [4], [5] of the batteries. Especially, the fast charging of the battery to a state-of-charge close to 80% in less than 15 minutes is generally assumed to be of paramount importance. The goal of performance improvement and cost reduction of LIBs has led to different and novel attractive battery concepts. Generally a higher energy density can be achieved by increasing the areal capacity through larger electrode thickness or higher electrode density. However, increasing the active material loading can cause transport limitations of the shuttling lithium ions which also reduce the rate capability and practical capacity of the cell [Reference]. Recent simulation studies on structuring techniques performed by our group suggest that laser perforation of the electrodes could be a promising method enabling fast charging. The perforation creates a hierarchical pore network with macroscopic transport pathways between anode and cathode which enhances the transport in the electrolyte. In this contribution, we will present microstructure resolved electrochemical- thermal simulations [6] of NMC 111-graphite pouch cells within our software BEST. In particular, we will investigate the effect of structuring techniques on the thermal and electrochemical performance of the battery. The simulation results are able to provide insights on the influence of electrode structuring on fast-charging performance and have the potential to guide new developments in the field.

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