Sulfurized polyacrylonitrile (SPAN) is emerging as a promising cathode for high-energy Li metal batteries. The transition-metal-free nature, high capacity, good sustainability, and low cost serve as competitive advantages of SPAN over conventional layered-oxide counterparts. The unique structure of SPAN with abundant covalent C–S and N–S bonds enables it to achieve high electrochemical performance even in lean electrolyte conditions. Despite great research progress, the current performance of Li/SPAN batteries still falls far behind its true potential. Here, we thoroughly analyze the energy density and cycle life of practical Li/SPAN cells based on our in-house-developed models. Besides, using Sand’s equation, we derive the requirements for Li/SPAN cells to achieve a reasonable power density and discuss their implications. Our analyses address critical issues of Li/SPAN on both material and cell levels, with an emphasis on particularly crucial details that are often overlooked or misunderstood. Accordingly, the challenges and directions for future Li/SPAN research are indicated.

硫化聚丙烯腈（SPAN）正在成为高能锂金属电池的一种有前途的阴极。与传统层状氧化物同类产品相比，SPAN 不含过渡金属、高容量、良好的可持续性和低成本，具有竞争优势。 SPAN独特的结构具有丰富的共价C-S和N-S键，使其即使在贫电解质条件下也能实现高电化学性能。尽管研究取得了巨大进展，但 Li/SPAN 电池目前的性能仍远远落后于其真正潜力。在这里，我们基于我们内部开发的模型全面分析了实用 Li/SPAN 电池的能量密度和循环寿命。此外，利用 Sand 方程，我们推导了 Li/SPAN 电池达到合理功率密度的要求，并讨论了它们的含义。我们的分析解决了 Li/SPAN 在材料和电池层面上的关键问题，重点关注经常被忽视或误解的特别关键的细节。因此，指出了未来Li/SPAN研究的挑战和方向。