Size‐dependent failure behavior of commercially available lithium‐iron phosphate battery under mechanical abuse

Abstract

Under mechanical abuse, the failure of lithium‐ion batteries occurs in various stages, characterized by different force, temperature, and voltage responses, and require in situ measurements for analysis. First, four sizes of commercially available lithium‐iron phosphate batteries (LFPB), namely 18650, 22650, 26650, and 32650, were subjected to quasistatic lateral and longitudinal compression and nail penetration tests. The failure, characterized by the voltage drop and temperature rise at the onset of the first internal short‐circuit (ISC), was identified by an Aurdino‐based voltage sensor module and a temperature measurement module, respectively. The battery failure load and peak temperature at the onset of ISC were found to rely strongly on the battery size. The failure was delayed for small‐sized 18650 batteries during lateral compression, unlike in longitudinal compression and nail penetration tests. At the onset of ISC, the temperature rise above the ambient value was different for different LFPBs. It was found to be maximum (36.4°C) for LFPB 32650 under longitudinal compression and minimum (1.5°C) under lateral compression tests among the considered geometries. Further, LFPB 26650 exhibited a balanced thermal behavior during the test. Such thermal response can be sensed timely for effective thermal management of lithium‐ion batteries.