Lithium-sulfur batteries are among the next-generation electrochemical storage technologies due to their potentially low material cost and high energy density. Typically, they consist of a sulfur-based cathode, a lithium-metal anode, and an organic electrolyte. However, these components face issues such as cathode volume expansion, lithium dendrite formation, and shuttling of dissolved polysulfides during cycling, which leads to limited cyclability of typically less than 300 cycles under near-practical conditions. Now, Yunhui Huang, Zhen Li and colleagues at Huazhong University of Science and Technology assemble ampere-hour pouch cells with sulfurized pyrolyzed polyacrylonitrile-based cathodes and graphite anodes, either one of which is pre-lithiated, exhibiting over 1,000 cycles with a capacity retention of 82%.

Replacing the usual lithium-metal anode with a graphite anode avoids dendrite formation and side reactions, while sulfurized pyrolyzed polyacrylonitrile mitigates the polysulfide shuttle effect in the chosen electrolyte and reduces the cathode volume expansion. To make the cell work, the researchers also adopt a simple lithiation method by attaching a thin lithium foil to the anode or cathode surface before assembly. This introduces lithium ions and facilitates their intercalation and deintercalation, extending the cycle life. Nevertheless, Huang, Li, and team found that long cycle life can only be achieved by limiting the depth of discharge to 80% as higher depths cause loss of active lithium and increased resistance. Despite the need for improvements in energy density, the batteries benefit from low materials cost and enhanced safety, as noted by the researchers.

锂硫电池由于其潜在的低材料成本和高能量密度而成为下一代电化学存储技术之一。通常，它们由硫基阴极、锂金属阳极和有机电解质组成。然而，这些组件面临着诸如阴极体积膨胀、锂枝晶形成以及循环过程中溶解的多硫化物的穿梭等问题，这导致在接近实际的条件下循环能力有限，通常小于 300 次循环。现在，华中科技大学的 Yunhui Huang、Zhen Li 及其同事将安时软包电池与硫化热解聚丙烯腈基阴极和石墨阳极组装在一起，其中任何一个都经过预锂化，表现出超过 1,000 次循环的容量保持率82%。

用石墨阳极代替常用的锂金属阳极可以避免枝晶形成和副反应，而硫化热解聚丙烯腈可以减轻所选电解质中的多硫化物穿梭效应并减少阴极体积膨胀。为了使电池正常工作，研究人员还采用了一种简单的锂化方法，即在组装前将薄锂箔附着到阳极或阴极表面。这引入了锂离子并促进其嵌入和脱嵌，从而延长了循环寿命。尽管如此，Huang、Li 和团队发现，只有将放电深度限制在 80% 才能实现长循环寿命，因为更高的深度会导致活性锂的损失和电阻的增加。研究人员指出，尽管需要提高能量密度，但电池仍受益于较低的材料成本和增强的安全性。