【Frontiers in HaiChuan Chemical Technology】Shanghai Jiao Tong University achieves breakthrough results in lithium-sulfur batteries
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One battery, with a single charge, can enable your electric vehicle to travel 1,000 kilometers! On March 4, a research team from Shanghai Jiao Tong University published a groundbreaking research finding in the international journal ‘Carbon Future’. The new lithium-sulfur battery they developed retained a high capacity of 601 milliampere-hours per gram even after 300 charge-discharge cycles, which means that future electric vehicles might be able to travel from Beijing to Shanghai on a single charge, and mobile phone batteries might only need to be charged once a week! Lithium-sulfur batteries: The buried \"superstar\". You might ask, if lithium-sulfur batteries are so great, why do our smartphones and electric vehicles still use lithium-ion batteries? In fact, the theoretical energy density of lithium-sulfur batteries is as high as 2500 watt-hours per kilogram, which is nearly 10 times that of current commercial lithium-ion batteries. In simple terms, for batteries of the same weight, lithium-sulfur batteries can store 10 times as much energy as lithium-ion batteries! Moreover, sulfur is abundant on Earth, inexpensive, and environmentally friendly – it sounds like the perfect material for batteries! But things are not that simple.
The \"three-strategy approach\" of the Shanghai Jiao Tong University team: Instead of avoiding these challenges, the research team from Shanghai Jiao Tong University took them on head-on. They devised a TiO₂@NPC@S composite cathode material with a multi-level porous structure. First, they created a \"three-dimensional highway network\": by utilizing the porous structures derived from metal-organic frameworks (MOFs), they developed a three-dimensional network that combines micropores, mesopores, and macropores – similar to the three layers of urban transportation network consisting of overpasses, ground levels, and underground passages. This structure not only provides sufficient space to accommodate sulfur but also offers \"highways\" for electrons and ions to move through. Second, it creates a \"flexible sponge\": this porous structure functions like a sponge, enabling it to absorb the volume changes that occur during battery charging and discharging, thereby preventing the structure from collapsing. Thirdly, \"molecular traps\" are created: chemical bonds form between TiO₂ and sulfur, acting like molecular-level \"traps\" that firmly capture those polysulfides that attempt to \"pass through\".
Shocking experimental results: This innovative material demonstrated remarkable performance in tests. Firstly, at a charging rate of 0.5C, its initial capacity was as high as 1327.35 mAh/g； Secondly, after 300 cycles, the capacity remains at 601.54 mAh/g, with an average capacity degradation of only 0.16% per cycle ； Thirdly, it boasts excellent rate performance: 928 mAh/g at a 1C rate and 743 mAh/g at a 1.5C rate. It should be noted that under the same conditions, the capacity of the commercial control sample Y-50@S decreased to below 168.16 mAh/g after 100 cycles, and was almost zero after 300 cycles! It’s like two runners: one maintains a strong pace after 300 laps, while the other is out of breath after just 100 laps.
Three major challenges: Although this research has achieved significant breakthroughs, there are still three major challenges before it can be applied on a large commercial scale. The first is the issue of cost and mass production: The synthesis and processing of MOF materials are relatively expensive, and ways to achieve low-cost mass production still need to be explored. Second is the overall battery system: Research focuses mainly on the cathode material, but a complete lithium-sulfur battery system also includes the electrolyte, separator, and anode, all of which require comprehensive optimization. Third is safety and long-term stability: The safety in actual application environments and stability over longer periods (such as more than 1,000 cycles) still need to be verified. Nevertheless, this research still offers new possible pathways for the commercialization of lithium-sulfur batteries. As technology continues to improve, we may soon see electric vehicle and mobile phone batteries with capacities several times higher than those available today.