Failure mechanism and predictive model of lithium-ion batteries under extremely high transient impact

Highlights

• The voltage of lithium-ion batteries under high impact is measured, with a sharp drop and slow rise.

• The partial short circuit of the separator and the relaxation effect contribute to the impact failure.

• MI-PNGV model is proposed to simulate the failures under different extreme mechanical conditions.

• The design guideline is proposed to avoid the mechanic impact failure of lithium-ion batteries.

Abstract

With the advantage of high energy density, lithium batteries are widely used in industrial and military applications. However, under the complex conditions of vehicle collision and high-speed flight ammunition, lithium-ion batteries have functional failure, which seriously affects the safety and stability of systems using batteries. In this paper, research on the electric parameter drift of lithium-ion batteries under high impact is carried out through a machete test system, and the experimental phenomena are analyzed theoretically. Based on this, an equivalent circuit model is established to analyze the failure phenomenon and mechanism of lithium-ion batteries under more extreme impact scenarios, which are difficult to test in the laboratory. Finally, the mechanical impact dynamic (MID) model of lithium-ion batteries at the moment of high impact is established, and the influence of separator thickness, elastic modulus and other parameters on the impact resistance of lithium-ion batteries is revealed, which provides a reference for the optimization design of lithium-ion batteries under a high-impact environment.

Introduction

Due to their high energy density and high power density advantages, lithium batteries are widely used in industrial and military applications [1], [2], [3], [4], [5], [6]. In industry, lithium batteries are usually used as power supplies of electric vehicles and energy storage power stations for photovoltaic power generation. Military weapon equipment is usually used as the main energy source of missile guidance systems and ammunition fuze. In these application scenarios, lithium-ion batteries are faced with extremely high acceleration impacts, under which their safety and reliability are very important [7], [8], [9]. For example, the impact in the process of electromagnetic gun launching (Fig. 1a) can reach 20,000 g, and the failure of the fuze power supply can easily cause the fuze to output an incorrect initiation signal, which will cause bore explosion and other safety problems. The impact of the penetration process (Fig. 1b) before initiation will exceed 1,00,000 g, and the power failure of the fuze causes misfire of the penetration fuze. The transient impact of electric vehicles (Fig. 1c) reaches tens or even hundreds of g, and the failure of lithium-ion power batteries may cause thermal runaway (TR), leading to secondary disasters such as fires.

What distinguishes the current study is nonintrusive loading, since most studies in the literature have focused on intrusive loadings (i.e., indentation, nail penetration, etc.), either under quasi-static loading or under dynamic loading [10], [11], [12], [13]. Li [14], [15], [16] studied the mechanism of mechanical failure and its correlation with the electrical response. Pan et al. [17,18] studied the impact load and dynamic effect on lithium batteries. Zhou et al. [19] revealed different mechanical-electrochemical coupled failure mechanisms and safety evaluations of lithium-ion pouch cells under dynamic and quasi-static mechanical abuse. Jia et al. [20] studied unlocking the coupling mechanical-electrochemical behavior of lithium-ion batteries upon dynamic mechanical loading. Chen et al. [21,22] experimentally studied the dynamic behavior of prismatic lithium-ion batteries upon repeated impact and revealed the dynamic behavior and modeling of prismatic lithium-ion batteries. Xia et al. [23] studied the failure behavior of 100% state of charge (SOC) lithium-ion battery modules under different impact load conditions and evaluated the mechanical response of commercial lithium-ion battery modules under various impact conditions, as well as the possibility of TR after impact. E. Sahraei et al. [24] carried out quasistatic tests on cylindrical and pouch cells under different loads and boundary conditions, revealing the relationship between the occurrence and development of internal short circuit and mechanical response characteristics. Greve and Fehrenbach [25] incorporated the Mohr-Coulomb fracture criterion into the battery model and then simulated and experimentally verified the temperature distribution of the battery under various mechanical loads. Xu et al. [26,27] studied the mechanical integrity of cylindrical batteries under different loading conditions (such as nail penetration, compression and bending) and established a calculation model of the coupling strain rate and SOC of lithium-ion batteries. Ren et al. [28], [29], [30], [31], [32] revealed the following chain reaction of mechanical abuse, electrical abuse and thermal abuse of lithium batteries: high impact can easily cause mechanical abuse, resulting in short circuit heat generation of lithium-ion batteries, and then, TR is triggered. These works successfully established a research framework combining experimental test characterization and dynamic theoretical modeling for the study of mechanical impact-induced mechanical thermal coupling failure of lithium-ion batteries.

However, in military scenarios such as electromagnetic railgun launches and ground penetrating bomb attacks on solid fortifications, the mechanical impact of lithium-ion batteries is more extreme than that in the existing research, and the safety problem caused by thermal runaway is no longer the only major threat. First, the mechanical impact in these military scenarios has the characteristics of high acceleration (> 30,000 g), narrow pulse width (< 1 ms) and high transient potential [33]. The quasi-static mechanical assumption adopted in previous studies is no longer tenable and the coupling of the transient mechanical model and the lithium-ion battery dynamic model needs to be considered. In addition, even if there is no thermal runaway, the transient fluctuation of the output electrical characteristics of lithium-ion batteries will also pose a fatal threat to the reliability of ammunition electronic systems in these scenarios [34]. In particular, there is no effective experimental simulation method for the most extreme mechanical impact environments, such as an electromagnetic gun launching process [35]. The reliability design of lithium-ion batteries in these environments will depend more on the prediction of theoretical model simulations.

To solve the above problems, in this paper, the high transient impact environment of a single-layer concrete target penetration process is tested with an experimental machete system, and detailed electrical behaviors during the impact process of lithium-ion batteries are obtained. Furthermore, based on experimental data, the dominant physical mechanism of lithium-ion battery failure is analyzed, an equivalent circuit model and a dynamic model are established, and the simulation calculation is in agreement with the experimental results. Through the established model, the response of lithium-ion batteries under more extreme electromagnetic launching scenarios is simulated, and the influence of separator size and material parameters on the transient failure characteristics of lithium-ion batteries is analyzed, which provides a theoretical tool for further research on the protection and reliability design of lithium-ion batteries in these extreme mechanical environments.