Li4Ti5O12 nanowire array as a sulfur host for high performance lithium sulfur battery

Lithium sulfur batteries (LSBs) have been recognized as one of the most promising next generation rechargeable batteries due to their high specific capacity and energy density. However, the practical application of LSBs is hindered by the low sulfur utilization due to the insulation nature of sulfur, and by the serious capacity fading of sulfur cathode arising from "shuttle effect" of polysulfides during the discharge-charge process. Herein we design and fabricate a 3D structured sulfur cathode based on Li₄Ti₅O₁₂ nanowire array (LTOWA) to address these issues. In this cathode, the 3D nanowire array structure can facilitate electron transport and provide satisfactory electrochemically active surface where electron and Li ions can meet with the sulfur for fast conversion reaction, ensuring the high sulfur utilization of cathode even with a large areal sulfur content; in addition, we also show, by X-ray photoelectron spectroscopic and electrochemical analyses, that LTO can immobilize the migrating polysulfide intermediates via Ti–S bond more effectively than the conventionally used TiO₂ (TO), which adsorbs polysulfide mainly through O–S bond. As a result, the LTOWA/sulfur composite cathode with a high sulfur loading (4 mg cm⁻²) shows a high utilization of sulfur (1100 mAh g⁻¹ at 0.02C) and excellent cycle life (80% capacity retention after 300 cycles at 1C, namely 0.06% per cycle). Our work suggests that the performance of polar oxide/sulfur composite cathodes can be further improved by the synergistic effect of more effective chemical bonds and architectural design.