Lithium–Sulfur Rechargeable Battery Cells with SPAN/Resin Film Cathodes for Lightweight and Safety

Abstract

Lithium–sulfur (Li–S) rechargeable batteries, LSBs, have been reported to possess high gravimetric energy densities (GEDs) of over 500 Wh kg_(cell)⁻¹ at the single-cell level (including weights of battery tabs and cases) and are greatly anticipated as one of the next-generation lightweight batteries. However, GED and safety demonstrations of the LSBs with practical battery cell designs are limited, and their commercialization has been slow. Here, we created newly designed LSB pouch cells named LiLiSPRing-model ADETAMA, using practical approaches, combining sulfurized polyacrylonitrile (SPAN; ADEKA AMERANSA SAM series) as the cathode active material and an Al-resin film (trilayer Al/PET/Al) as the cathode current collector, which have been reported to exert remarkable rechargeable battery performances. The LSB (Li–SPAN) pouch cell, SPAN/Al-resin film cathode | high-concentrated ether-based electrolyte solution | Li–metal anode (Li–SPAN/Al-resin film), weighing 25.2 g (including weights of battery tabs and pouch cases), exhibited discharge characteristics of 9.27 Ah capacity and 1.50 V average voltage at 3rd cycle in 0.05C-rate, 0.30 V cut-off, 25 °C, and cell pressurization of 507 kPa (5.0 atm). We have succeeded in achieving a high GED of 552 Wh kg_(cell)⁻¹, well above the GEDs of lithium-ion rechargeable batteries in commercial use or under development. While 9 Ah, 550 Wh kg_(cell)⁻¹-class SPAN cells cannot yet sustain stable long-term charge-and-discharge cycling, similar <1 Ah single-layer pouch cells indicate potential for several dozen cycles. In addition to the lightweight characteristic, the Li–SPAN/Al-resin film pouch cell with 503 Wh kg_(cell)⁻¹ (9.21 Ah and 14.1 Wh) exhibited a high ignition safety property in a nail-penetration test for a short-circuit. These results obtained by the state-of-the-art technology would contribute to the practical application of next-generation LSBs and lead to the adoption of lightweight batteries in flying vehicles such as high-altitude platform station (HAPS) or others.