固态锂硫电池在下一代储能领域的研究进展

对高性能储能系统日益增长的需求，加速了传统锂离子电池替代方案的研发进程。锂硫电池（Li-S）因其高达2600 Wh kg的理论能量密度而获得广泛应用⁻¹低成本以及硫的环境友好特性使其具有显著优势。然而传统锂硫体系面临多重挑战，包括多硫化物穿梭效应、锂枝晶形成以及循环寿命受限等问题。通过采用固态电解质（SSEs）替代易燃液体电解质，系统安全性和稳定性得到显著提升。固态锂硫（SSLS）电池的最新进展包括：开发高电导率固态电解质（硫化物、卤化物、聚合物-陶瓷复合材料）、设计适应体积变化的电极以降低界面阻抗，以及优化正极结构以改善离子/电子传输性能。本综述系统梳理了过去十年固态锂硫电池的研究进展。该技术的发展动力源于其实现更高能量密度与强化安全性的潜力，这两大特性对下一代储能系统至关重要。本综述亦聚焦于作为固态锂硫电池（SSLS）性能关键赋能者的固态电解质，探讨了液态电解质存在的可燃性、多硫化物穿梭效应及锂枝晶形成等挑战。最后，本文重点阐述了集成化电池设计的重要性——通过优化电极结构与先进固态电解质的协同作用，可实现性能最大化。

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关键词

锂硫电池
; 
全固态电池
; 
能量密度与未来电池技术

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引言

Lithium-sulfur (Li–S) batteries have been exhibiting the remarkable theoretical capacities of both lithium (3,860mAh g⁻¹) and sulfur (1,675mAh g⁻¹) electrodes [[1], [2], [3]]. However, a major challenge for liquid Li–S batteries is the "shuttle effect.” This phenomenon occurs during the reaction of sulfur dissolve into the liquid electrolyte and migrate to the anode by the formation of polysulfides. Such migration has led to a loss of active materials and reduces battery efficiency [4]. Although the design of carbon scaffolds to trap sulfur can help in the mitigation of this issue, a more promising approach is required to eliminate the shuttle effect by replacing liquid electrolytes with solid-state electrolytes. Various solid-state options are available, including polymers, oxides, halides [5], and sulfides [6,7]. However, polymer electrolytes often suffer from low ionic conductivity at room temperature and do not fully suppress the shuttle effect of lithium polysulfides [8]. Oxide electrolytes are mechanically strong, and hence difficult to integrate into the sulfur cathodes [9]. Halide electrolytes, despite their high ionic conductivity and voltage stability, it has an undesirable electrochemical reactions with lithium metal anodes [[10], [11], [12], [13]]. All-solid-state lithium batteries (ASSLBs) offer advantages over conventional batteries, including enhanced safety, higher energy density, and improved cycling stability. These benefits are obtained due to the replacement of volatile liquid electrolytes with solid-state electrolytes. However, challenges in materials design, interfacial stability, and scalable manufacturing continue to hinder their widespread commercialization [[14], [15], [16], [17], [18]]. Recent advancements in machine learning, coupled with the integration of automated high-throughput screening, have significantly accelerated the materials discovery process [19]. To address the growing need for increased energy density, a promising approach is the formation of advanced electrode materials. However, both conventional lithium-ion batteries (LIBs) and LSBs have a critical drawback: the inherent safety risks posed by their flammable and leakage-prone liquid electrolytes. A viable solution to this problem is the adoption of solid electrolyte. Moreover, a crucial aspect of modern technological development is ensuring its practical applicability. For instance, data indicate that nearly half (47.95 %) of the world's land experiences average winter temperatures below freezing [20]. The quest for commercially viable, ultra-high-energy-density, all-solid-state Li–S batteries has driven research into the impact of electrode composition on mass energy density. Initial analyses, assuming full sulfur utilization, focused on various solid electrolytes such as polymer PEO, oxide LLZO, sulfide LPSCl, and halide LiInCl. The findings have indicated that PEO-based batteries offered the highest energy density, a performance trend that inversely represented the densities of the electrolytes used (PEO: 1.2 g/cm³, LPSCl: 1.64 g/cm³, LiInCl: 2.59 g/cm³, LLZO: 5.1 g/cm³). This suggests that a lower solid electrolyte density is beneficial for maximizing the energy density [21,22]. Further investigations have highlighted that increasing sulfur loading significantly boosts the mass energy density. Optimizing the negative-to-positive (N/P) ratio is crucial; values approaching unity yield the high mass energy density, whereas higher ratios lead to reductions. Similarly, enhancing the sulfur content, whether through increased content at fixed loading or higher loading at fixed content, has consistently improved the mass energy density. Zhao et al. [23] described the overcoming of polysulfide shuttling and slow redox kinetics in thick sulfur cathodes, which requires novel cathode design strategies, specifically those utilizing selenium-sulfur chemistry and cathode host engineering. Fig. 1A shows that high-performance lithium-sulfur batteries with excellent energy retention and extended cycling stability are required. Fig. 1B depicts an overview of the key issues hindering the development of useable Li–S cells.
向固态电解质（SSEs）的转变之所以受到关注，主要源于传统液态电解质的重大缺陷：其易燃性会引发安全隐患。液态电解质还会导致一系列挑战，如电解质分解、锂硫电池中的多硫化物穿梭效应、锂金属负极上的枝晶生长，以及工作温度范围受限和电池寿命缩短等问题。SSEs因其不可燃特性从根本上缓解了这些问题，安全性提升是其核心优势[24,25]。它们能有效抑制多硫化物的穿梭效应，并具备潜在的枝晶抑制能力，从而实现了高能量密度锂金属负极的应用[26]。此外，固态电解质支持更宽的工作温度范围。尽管固态电池研究始于50多年前，但早期发展受限于低离子电导率和高界面阻抗[27]。Ohno等[28]的研究表明，硫在锂化/脱锂过程中的显著体积变化会导致复合材料内部接触失效（如图2a所示）。这种化学-机械失效通过破坏高效的离子/电子传输路径，以及缩减对电池性能至关重要的三相边界，从而干扰可逆电化学（氧化还原）反应。
图2b展示了限制电池性能的主要因素，包括阳极锂枝晶生长以及硫正极与固体电解质之间的界面接触不足。活性物质分布不均导致界面电子和离子传输性能恶化。在电化学循环过程中，硫转化为硫化锂（S₈+ 16Li⁺+ 16e⁻→ 8Li₂硫（S）正极材料在充放电过程中经历了约80%的体积变化，导致正极结构产生裂纹与孔隙。这些机械形变会破坏电传导与离子传输的连续性，增加电池内阻，并在反复充放电循环中加速容量衰减。
图2c展示了全固态锂硫电池技术经过十年发展后的现状，而图2d则呈现了2015至2025年间的发表趋势，揭示了从液态体系向固态体系的转变。本综述首先涵盖固体电解质的突破性进展，重点阐述材料特性、离子电导率和电化学稳定性。随后探讨了近期为适配固态体系开发的电极设计创新，特别是硫正极方面的研究。接着对全电池构型进行评估，重点关注界面接触与相容性问题。最后，综述对未来发展前景、当前挑战以及推动SSLS电池技术进步的潜在研究方向进行了总结。