▎ 摘　　要

NOVELTY - Producing sulfur cathode, comprises (a) preparing a humic acid-derived foam or combined humic acid/graphene-derived foam composed of multiple pores and pore walls, where the pore walls contain one or many hexagonal carbon atomic planes, and (b) impregnating the foam with sulfur or sulfide in the form of thin particles or coating, having a diameter or thickness less than 500 nm, which are lodged in the pores or deposited on the pore walls. USE - The process is useful for producing sulfur cathode which is useful in a metal-sulfur battery (claimed) e.g. lithium-sulfur battery, sodium-sulfur battery, magnesium-sulfur battery and aluminum-sulfur battery. ADVANTAGE - The process: provides the metal-sulfur battery that exhibits an exceptionally high specific energy density or high volumetric energy density, high elastic modulus, high mechanical strength, a high cathode active material utilization rate, good resistance to dendrite formation, little or no shuttling effect and a long and stable cycle life; provides the metal-sulfur or metal ion-sulfur cell with a cell specific energy greater than 400 Wh/kg, preferably greater than 600 Wh/kg (all based on the total cell weight); provides the metal-sulfur cell that exhibits a high cathode specific capacity (higher than 1200 mAh/g based on the sulfur weight or higher than 1000 mAh/g based on the cathode composite weight including sulfur, conducting additive or substrate, and binder weights combined, but excluding the weight of cathode current collector) and the specific capacity is preferably higher than 1400 mAh/g based on the sulfur weight alone or higher than 1200 mAh/g based on the cathode composite weight; provides the metal-sulfur battery; utilizes the carbon nano material that requires a reduced amount of undesirable chemical (or elimination of these chemicals all together), shortened process time, less energy consumption, reduced or eliminated effluents of undesirable chemical species into the drainage (e.g. sulfuric acid) or into the air (e.g. sulfur dioxide and nitrogen dioxide); utilizes the foam material that is thermally and electrically conducting, mechanically robust, and chemically compatible with sulfur or polysulfide; and is cost-effective without requiring the need of environmentally unfriendly chemical while enabling the flexible design and control of the porosity level and pore sizes, preferably a meso-scaled pore size of 2-50 nm. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a roll-to-roll process for producing a continuous-length sheet of the humic acid-derived foam, comprising preparing a humic acid dispersion having humic acid molecules and optional graphene sheets dispersed in a liquid medium, where the dispersion contains a blowing agent, continuously or intermittently dispensing and depositing the humic acid dispersion onto a surface of a supporting substrate to form a wet layer of humic acid, where the supporting substrate is a continuous thin film supplied from a feeder roller and collected on a collector roller, partially or completely removing the liquid medium from the wet layer of humic acid to form a dried layer of humic acid in a heating zone or multiple heating zones, and heat treating the dried layer of humic acid in one of the heating zones containing a heating temperature of 80-500 degrees C at a desired heating rate sufficient to activate the blowing agent for producing the humic acid-derived foam, which is composed of multiple pores and pore walls, where the pore walls contain single-layer or few-layer humic acid-derived hexagonal carbon atomic planes, the few-layer hexagonal carbon atomic planes have 2-10 layers of stacked hexagonal carbon atomic planes having an inter-plane spacing d002 of 0.3354-0.6 nm as measured by X-ray diffraction, and the single-layer or few-layer hexagonal carbon atomic planes contain 0.01-25 wt.% of non-carbon elements.