Lithium‑selenium (Li–Se) batteries are considered as promising candidates for the next generation battery technology due to their high volumetric energy density and low cost. Compared with Se cathode in Li–Se batteries, Li₂Se cathode can not only alleviate the negative effect of volume expansion in the cycle process, but also avoid utilizing lithium foil as the anode. However, Li₂Se has received little coverage due to its high cost and difficulty in production. Herein, two facile synthesis routes, including ball milling and direct heating, are successfully developed to produce pure Li₂Se particles by reacting LiH powers with Se powers (2LiH + Se = Li₂Se + H₂↑). The microstructure of Li₂Se particles is investigated by cryogenic transmission electron microscopy (cryo-TEM) technology for the first time. The Li₂Se cathode with layer-by-layer structure exhibits superior electrochemical performance at high loading (698 mA h g⁻¹@50 mA g⁻¹@10.6 mg cm⁻²; 333 mA h g⁻¹@1000 mA g⁻¹@7.1 mg cm⁻²), attributed to the high polyselenides-trapping and reutilization capability of active layer as well as the excellent polyselenides-interception and high conductivity of barrier layers. This innovative synthesis strategy of Li₂Se and the intriguing design of cathodic structure are highly expected to promote the practical implementation of the safer high energy-density Li–Se batteries.

锂硒（Li-Se）电池由于具有高体积能量密度和低成本而被认为是下一代电池技术的有希望的候选者。与Li-Se电池中的Se阴极相比，Li ₂ Se阴极不仅可以减轻循环过程中体积膨胀的负面影响，而且可以避免使用锂箔作为阳极。然而，Li ₂ Se由于其成本高且生产困难而几乎没有覆盖。在本文中，成功开发了两种可行的合成路线，包括球磨和直接加热，通过使LiH功率与Se功率（2LiH + Se = Li ₂ Se + H ₂ ↑）反应来生产纯Li ₂ Se颗粒。Li ₂的微观结构硒颗粒首次通过低温透射电子显微镜（cryo-TEM）技术进行了研究。具有分层结构的Li ₂ Se阴极在高负载下表现出优异的电化学性能（698 mA hg ^-1 @ 50 mA g ^-1 @ 10.6 mg cm ^-2 ; 333 mA hg ^-1 @ 1000 mA g ^-1 @ 7.1mg cm ^-2），归因于活性层的高硒化物捕获和再利用能力以及优异的聚硒化物拦截和阻挡层的高电导率。Li _2的这种创新合成策略人们高度期望Se和引人入胜的阴极结构设计能够促进更安全的高能量密度Li-Se电池的实际应用。