Carbonized Waste Milk Powders as Cathodes for Long-Term Stable Lithium-Sulfur Batteries with Ultra-Large Capacity and High Initial Coulombic Efficiency

Abstract To explore the natural resources as sustainable precursors offers a family of green materials. Use of bio-waste precursors especially remaining from food processing is a scalable, highly abundant, available and cost-effective strategy. Exploring the waste materials synthesis route is highly important especially for new materials discovery in emerging energy storage technologies such as lithium sulfur batteries (LSBs). Herein, simple, green and abundant waste milk powder is carbonized (CMP) and constructed as the sulfur host with the hollow micro-/mesoporous framework, resulting CMP and sulfur (CMP/S) composites are employed as cathodes for LSBs. It is revealed that the hollow micro-/mesoporous CMP/S framework can not only accommodate the volume expansion but also endow smooth pathways for the fast diffusion of electrons and Li-ions, leading to both high capacity and long cycling stability. The CMP/S composite electrode with 56 wt.% loaded sulfur exhibits a remarkable initial capacity of 1596 mAh g-1 at 0.1 C, corresponding to 95% of the theoretical capacity. Even at a rate of 1 C, it maintains a high capacity of 730 mAh g-1 with a capacity retention of 72.6% after 500 cycles, demonstrating a very low capacity fading of only 0.05% per cycle. Importantly, the Coulombic efficiency is always higher than 96% during all the cycles. The only used source material is expired waste milk powders in our proposal and we believe that this “trash to treasure” approach will open up a new way for the utilization of waste material as environmentally safe and high performance electrodes for advanced LSBs.