Lithium recovery from an aqueous resource was accelerated by electrochemically driving the transformation of MnIV /MnIII with a spinel λ-MnO2 film electrode. A λ-MnO2 electrode without binders or conductive additives is preferred for achieving a large capacity at high current density and long-term cycling capability. In this study, a film of Mn(OH)2 was first deposited on the surface of Pt or graphite substrates owing to alkalization near the cathode, then it was oxidized to a Mn3 O4 film by air, followed by being hydrothermally lithiated to LiMn2 O4 spinel and, finally, it was turned into the λ-MnO2 film electrode through potentiostatic delithiation. The results show that the charging/discharging electric capacity of the fabricated λ-MnO2 film electrode was up to ≈100 mAh g-1 at a current density of 50 mA g-1 in 30 mm Li+ aqueous solution, twice that of the λ-MnO2 powder electrode. Also, 82.3 % lithium capacity remained after 100 cycles of an electrochemically assisted lithium recovery process, indicating high availability and good stability of the λ-MnO2 spinel on the electrode. The energy consumption for each cycle is estimated to be approximately 1.55±0.09 J, implying that only 4.14 Wh is required for recovery of one mole of lithium ions by this method.

中文翻译：

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一种自支撑的λ-MnO2薄膜电极，用于从卤水中回收电化学锂。

通过用尖晶石λ-MnO2薄膜电极电化学驱动MnIV / MnIII的转变，加快了从水源中回收锂的速度。优选不使用粘合剂或导电添加剂的λ-MnO2电极，以在高电流密度和长期循环能力下实现大容量。在这项研究中，由于阴极附近的碱化作用，首先在Pt或石墨基板的表面上沉积了Mn（OH）2膜，然后通过空气将其氧化为Mn3 O4膜，然后对其进行水热锂化为LiMn2 O4。尖晶石，最后通过恒电位脱锂转变为λ-MnO2薄膜电极。结果表明，在30 mm Li +水溶液中，电流密度为50 mA g-1时，制成的λ-MnO2薄膜电极的充电/放电电容高达≈100mAh g-1，是λ-MnO2粉末电极的两倍。同样，在100次循环电化学辅助的锂回收过程后，仍有82.3％的锂容量，这表明λ-MnO2尖晶石在电极上具有很高的利用率和良好的稳定性。估计每个循环的能量消耗约为1.55±0.09 J，这意味着通过此方法回收一摩尔锂离子仅需要4.14 Wh。