Core-shell structured Li-Fe electrode for high energy and stable thermal battery.

The thermal battery, a key source for powering defensive power systems, employs Li alloy-based anodes. However, the alloying increases the reduction potential of Li which lowers the overall working voltage and energy output. To overcome these issues, Li alloy must be replaced with pure Li. Utilizing pure Li requires a structure that can hold liquefied Li because the working temperature for the thermal battery exceeds the melting point of Li. The liquefied Li can leak out of the anode, causing short-circuit. A Li-Fe electrode (LiFE) in which Fe powder holds liquefied Li has been developed. In LiFE, higher Li content can lead to higher energy output but increases the risk of Li leakage. Thus, Li content in the LiFE has been limited. Here, we demonstrate a novel core-shell electrode structure to achieve a higher energy output. The proposed core-shell LiFE incorporates a high Li content core and a low Li content shell; high energy comes from the core and the shell prevents the Li from leakage. The fabricated core-shell structured electrode demonstrates the high energy of 9074 W s, an increase by 1.66 times compared to the low Li content LiFE with the conventionally used Li content (5509 W s).

Electrochemical properties of a lithium-impregnated metal foam anode (LIMFA FeCrAl) for molten salt thermal batteries.

Although numerous cathode materials with excellent properties have been developed for use in molten salt thermal batteries, similar progress is yet to be made with anode materials. Herein, a high-performance lithium-impregnated metal foam anode (LIMFA) is fabricated by impregnating molten lithium into a gold-coated iron-chrome-aluminium (FeCrAl) foam at 400 °C. A test cell employing the LIMFA FeCrAl anode exhibited a specific capacity of 2627 As g-1. For comparison, a cell with a conventional Li(Si) anode was also discharged, demonstrating a specific capacity of 982 As g-1. This significant improvement in performance can be attributed to the large amount (18 wt%) of lithium incorporated into the FeCrAl foam and the ability of the FeCrAl foam to absorb and immobilize molten lithium without adopting a cup system. For thermal batteries without a cup, the LIMFA FeCrAl provides the highest-reported specific capacity and a flat discharge voltage curve of molten lithium. After cell discharge, the FeCrAl foam exhibited no lithium leakage, surface damage, or structural collapse. Given these advantageous properties, in addition to its high specific capacity, LIMFA FeCrAl is expected to aid the development of thermal batteries with enhanced performance.

Hydrothermally synthesized homogeneous Ni-Mo-S structures on Ni-foam cathodes for thermal batteries.

Hydrothermally synthesized homogeneous structures based on Ni, Mo, and S on Ni metal foam cathodes (NiMoSs) were characterized electrochemically. A NiMoS-containing cell exhibited a much higher specific capacity of 1534 A s g-1 than an FeS2 cathode, owing to its homogeneous structure, demonstrating promise for thermal battery applications.