MOFs-like polyoxometalate (POMs) electrodes have already emerged as promising candidates for lithium-ion batteries (LIBs), yet the origins of the underlying redox mechanism in such materials remain a matter of uncertainty. Of critical challenges are the anomalously high storage capacities beyond their theoretical values and the fast ion diffusivity that cannot be satisfactorily comprehended in the theory of crystal lattice. Herein, for the first time we decode t2g electron occupation-regulated dual-redox Li-storage mechanism as the true origin of extra capacity in POMs electrodes. Enhanced V-t2g orbital occupation by Li coordination significantly triggers the Hubbard gap closure and reversible Li deposition/dissolution at surface region. Conjugated V-O-Li configuration at interlayers endow Li+ ion pathways along pore walls as the dominant contribution to the low migration barrier and fast diffusivity. As a result, remarkable cycle stability (~100 % capacity retention after 2000 cycles at 1 A g−1), extremely high specific capacity (1200 mAh g−1 at 100 mA g−1) and excellent rate performance (404 mAh g−1 at 8 A g−1) were achieved, providing new understandings on the underlying mechanism of POMs electrodes and pivotal guidance for dual-storage materials.

中文翻译：

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Hubbard Gap Close 诱导的双氧化还原储锂机制是类 MOF 多金属氧酸盐中异常高容量和快速离子扩散率的来源


类似 MOF 的多金属氧酸盐 （POM） 电极已成为锂离子电池 （LIB） 的有前途的候选者，但此类材料中潜在氧化还原机制的起源仍然是一个不确定的问题。关键的挑战是超出其理论值的异常高存储容量和快速离子扩散性，这在晶格理论中无法令人满意地理解。在此，我们首次解码了 t2g 电子占用调节的双氧化还原储锂机制，作为 POMs 电极中额外容量的真正来源。Li 配位增强的 V-t2g 轨道占据显着触发了表面区域的 Hubbard 间隙闭合和可逆的 Li 沉积/溶解。层间的共轭 V-O-Li 构型赋予沿孔壁的 Li+ 离子通路，这是对低迁移屏障和快速扩散率的主要贡献。结果，实现了显着的循环稳定性（在 1 A g-1 下循环 2000 次后保持 ~100% 的容量）、极高的比容量（100 mA g-1 时为 1200 mAh g-1）和出色的倍率性能（404 mAh g-1,8 A g-1），为对 POM 电极的潜在机制和双存储材料的关键指导提供了新的理解。