Homogenizing Li+ transport in high-loading sulfur cathodes enabled by synergy of all-in-one thin electrode design and a multifunctional binder for practical Li-S batteries

Abstract

Achieving high areal capacity is essential for high-energy-density Li–S batteries and requires using high-loading sulfur cathodes accompanied with increased coating thickness. However, poor Li+ transfer kinetics in thick electrodes and sluggish polysulfide conversion dramatically decrease active material utilization, particularly at high charge/discharge rates. To address these issues, we propose an all-in-one electrode design that employs a multifunctional binder to fabricate compact and thin high-loading sulfur cathodes. This integrated design effectively shortens Li+ transport path while accelerating Li+ diffusion rate, thereby enhancing Li+ uniformity within the high-loading electrode. In addition, the multifunctional binder provides excellent catalytic activity boosting polysulfide conversion. Consequently, the resultant high-loading sulfur electrode exhibits considerably improved rate performance compared with conventional thick electrodes. Under practical conditions (sulfur loading: 10.4 mg cm−2, sulfur content: 65 wt%, and E/S ratio: 3.6 μL mg−1), the Li–S battery achieves a high areal capacity of 9.01 mAh cm−2. Even with a lean binder content (2.5 wt%), a high-loading Li–S pouch cell exhibits stable cycling over 100 cycles and Ah-level pouch cell can be achieved, demonstrating the practical applicability. This study lights a new route to improve the rate property of practical high-loading sulfur cathodes.