Abstract Li metal, with the lowest thermodynamically achievable negative electrochemical potential and the highest specific capacity (3860 mAh g−1), is the ultimate anode choice for Li batteries. However, the highest reported Li plating/stripping Coulombic efficiency (CE) of 99.5% after extensive efforts is still too low for the Li metal-free (all the Li metal in cycling comes from cathode, without anode pre-lithiation) Li metal batteries. The low CE is attributed to both non-uniform Li plating/stripping on the lithiophobic Cu current collector and Li dendrite growth through lithiophilic organic–inorganic solid electrolyte interphase (SEI) formed in carbonate electrolytes. Here, we use a lithiophilic Bismuth graphite blend (Bi–Gr) substrate to replace lithiophobic Cu current collector to seed a uniform Li nucleation, and form a lithiophobic LiF-rich SEI rather than lithiophilic organic-rich SEI to suppress Li dendrite growth. Molecular dynamics simulations reveal the preferential reduction of anions in 2.0 M LiPF6 in tetrahydrofuran/2-methyl tetrahydrofuran (2.0 M LiPF6–mixTHF) electrolyte to generate LiF-rich SEI on plated Li. Bi–Gr substrate and 2.0 M LiPF6–mixTHF electrolyte enable the Li anodes to achieve a record high CE of 99.83% at a high capacity of 1.0 mAh cm−2 and current of 0.5 mA cm−2. The Bi particles serve as dispersed nucleation centers that promote uniform Li deposition with strong adhesion to the substrate to avoid dead Li, while the lithiophobic LiF-rich SEI promotes lateral Li growth and suppresses the vertical Li dendrite growth even at a high current density of 3.0 mA cm−2 and high areal capacities of 3.0 mAh cm−2. The regulation of Li nucleation and growth enables the Li metal-free LiFePO4 full cells to achieve 100 cycles at a practical areal capacity of >2.0 mAh cm−2. This manuscript highlights the benefits of simultaneous substrate design to improve Li nucleation and electrolyte design to promote lithiophobic SEI growth, enabling a promising and practical route Li metal-free Li metal batteries.

中文翻译：

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无金属锂电池的电解液设计

摘要 锂金属具有最低的热力学可实现的负电化学势和最高的比容量（3860 mAh g-1），是锂电池的最终负极选择。然而，经过广泛努力，报告的最高 99.5% 的锂电镀/剥离库仑效率 (CE) 对于无锂金属（循环中的所有锂金属来自阴极，没有阳极预锂化）锂金属电池来说仍然太低. 低 CE 归因于疏锂 Cu 集流体上不均匀的锂电镀/剥离和通过碳酸盐电解质中形成的亲锂有机-无机固体电解质中间相（SEI）生长的锂枝晶。在这里，我们使用亲锂的铋石墨混合物 (Bi-Gr) 基板代替疏锂的 Cu 集流体以形成均匀的 Li 成核，并形成疏锂富LiF SEI而不是亲锂富有机SEI以抑制锂枝晶生长。分子动力学模拟显示，在四氢呋喃/2-甲基四氢呋喃（2.0 M LiPF6-mixTHF）电解质中，2.0 M LiPF6 中的阴离子优先还原，以在镀锂上生成富含 LiF 的 SEI。Bi-Gr 基板和 2.0 M LiPF6-mixTHF 电解质使锂负极在 1.0 mAh cm-2 的高容量和 0.5 mA cm-2 的电流下实现了创纪录的 99.83% 的 CE。Bi 颗粒作为分散的成核中心，促进均匀的锂沉积，并与基板有很强的粘附力，以避免死锂，而疏锂的富含 LiF 的 SEI 促进横向锂生长并抑制垂直锂枝晶生长，即使在 3.0 的高电流密度下mA cm-2 和 3.0 mAh cm-2 的高面积容量。锂成核和生长的调节使无金属锂的 LiFePO4 全电池能够在 >2.0 mAh cm-2 的实际面积容量下实现 100 次循环。这份手稿强调了同时进行基板设计以改善锂成核和电解质设计以促进疏锂 SEI 生长的好处，从而为无锂金属锂金属电池提供了一条有前途且实用的路线。