High-surface-area, nanostructured carbon is widely used for encapsulating sulfur and improving the cyclic stability of Li–S batteries, but the high carbon content and low packing density limit the specific energy that can be achieved. Here we report an approach that does not rely on sulfur encapsulation. We used a low-surface-area, open carbon fibre architecture to control the nucleation and growth of the sulfur species by manipulating the carbon surface chemistry and the solvent properties, such as donor number and Li⁺ diffusivity. Our approach facilitates the formation of large open spheres and prevents the production of an undesired insulating sulfur-containing film on the carbon surface. This mechanism leads to ~100% sulfur utilization, almost no capacity fading, over 99% coulombic efficiency and high energy density (1,835 Wh kg⁻¹ and 2,317 Wh l⁻¹). This finding offers an alternative approach for designing high-energy and low-cost Li–S batteries through controlling sulfur reaction on low-surface-area carbon.

高表面积纳米结构碳被广泛用于封装硫和改善Li-S电池的循环稳定性，但是高碳含量和低堆积密度限制了可实现的比能。在这里，我们报告了一种不依赖于硫封装的方法。我们使用低表面积的开放式碳纤维架构，通过控制碳的表面化学性质和溶剂性质（例如供体数和Li ^+）来控制硫物质的形核和生长扩散性。我们的方法有助于形成大的开放球体，并防止在碳表面上产生不希望的绝缘含硫膜。该机制导致〜100％的硫利用率，几乎没有容量衰减，超过99％的库伦效率和高能量密度（1,835 Wh kg ^-1和2,317 Wh l ^-1）。这一发现为控制低表面积碳上的硫反应提供了另一种设计高能和低成本Li-S电池的方法。