Functionalized separators are expected to serve as protective barriers to conquer the lithium dendrite penetration in lithium metal batteries. Herein, a novel self-supporting separator material has been successfully synthesized based on the cellulose acetate and Keggin-type polyoxometalate H₃PMo₁₂O₄₀·xH₂O (denoted as CA/PMo₁₂). The incorporation of PMo₁₂ facilitates the transformation of the original finger-like structure of the CA separator into a uniform three-dimensional porous grid architecture, which is more effective in inhibiting the growth of lithium dendrites. For the obtained CA/PMo₁₂ separator, the mechanical strength, electrolyte uptake capacity, and Li⁺ anchoring ability are significantly improved. The plentiful ether and carbonyl functional groups of CA can effectively adsorb lithium ions and regulate the uniform lithium plating. More significantly, density functional theory calculations show that the coordination environment formed between PMo₁₂ and CA is conducive to enhancing the adsorption ability of lithium ions and promoting the rapid migration of lithium ions. Meanwhile, PMo₁₂ can act as an “ion sponge” to form a lithium-rich layer, making the distribution of charges on the lithium surface more uniform, while undergoing a reversible transformation between its reduced and oxidized states during repeated plating/stripping processes. Consequently, the Li//Li symmetric cell using a CA/PMo₁₂ separator shows excellent plating/stripping efficiency after 1075 cycles with a low hysteresis voltage of 38.1 mV under 5 mA cm⁻² and 1 mA h cm⁻². Meanwhile, a LiFePO₄//Li cell achieves a superior reversible capacity of 90 mA h g⁻¹ after 100 cycles under 1 C.

中文翻译：

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构建基于醋酸纤维素和多金属氧酸盐的枝晶抑制隔膜，以实现均匀的锂电沉积


功能化隔膜有望作为保护屏障，以征服锂金属电池中的锂枝晶渗透。在此，基于醋酸纤维素和 Keggin 型多金属氧酸盐 H₃PMo₁₂O₄₀·倍H₂O（表示为 CA/PMo₁₂）。PMo₁₂ 的掺入有助于将 CA 隔膜的原始指状结构转变为均匀的三维多孔网格结构，从而更有效地抑制锂枝晶的生长。对于获得的 CA/PMo₁₂ 隔膜，机械强度、电解液吸收能力和 Li⁺ 锚定能力均得到显著提高。CA 丰富的醚和羰基官能团可以有效吸附锂离子并调节均匀的镀锂。更重要的是，密度泛函理论计算表明，PMo₁₂ 和 CA 之间形成的配位环境有利于增强锂离子的吸附能力，促进锂离子的快速迁移。同时，PMo₁₂ 可以充当“离子海绵”，形成富锂层，使锂表面的电荷分布更加均匀，同时在重复电镀/剥离过程中在其还原态和氧化态之间发生可逆转变。因此，使用 CA/PMo₁₂ 隔膜的 Li//Li 对称电池在 1075 次循环后表现出优异的电镀/剥离效率，磁滞电压低至 38。在 5 mA ^cm-2 和 1 mA h ^cm-2 下为 1 mV。同时，LiFePO₄锂电池在 1 C 下循环 100 次后实现了 90 mA h ^g-1 的卓越可逆容量。