Lithium‐Ion Battery Testing Capable of Simulating “Ultralow” Lunar Temperatures

Abstract

The first‐ever lithium‐ion battery cycler capable of testing the coin and pouch cells under ultralow (≤40 °C) temperatures down to −175 °C to simulate extreme climates found in the lunar and space missions, high‐altitude air vehicles, polar regions of Earth, and military expeditionary missions is enthusiastically reported. The extremely cold temperatures are achieved through a tailored extreme low‐temperature system (ELTS) with liquid nitrogen flow and the ability to reach temperatures between −175 and 25 °C, using 1 kΩ and 1 MΩ resistors at varying currents of 1–4 mA and 1–4 μA, respectively, is validated. Employing the ELTS, Li4Ti5O12 (LTO)||Li cells with 1 m lithium bis(fluorosulfonyl)imide in cyclopentyl methyl ether as an electrolyte developed in this research group are charged and discharged at room temperature (cycling rate C/5), −20 (C/10), −40 (C/40), and −60 °C (C/50), which exhibited discharge capacities of 159.04, 119.12, 101.79, and 33.06 mAh g−1, respectively. Moreover, the LTO||Li cell produced a reversible capacity of 7.12 mAh g−1 tested at −100 °C for the first time.