A Self-Supported λ-MnO2 Film Electrode used for Electrochemical Lithium Recovery from Brines.
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.
['Xu|Xin|X|', 'Zhou|You|Y|', 'Feng|Zhiwen|Z|', 'Kahn|Naeem Ullah|NU|', 'Haq Khan|Zia Ul|ZU|', 'Tang|Yang|Y|', 'Sun|Yanzhi|Y|', 'Wan|Pingyu|P|', 'Chen|Yongmei|Y|http://orcid.org/0000-0003-1386-1574', 'Fan|Maohong|M|']
λ-MnO2 electrodes lithium recovery polypyrroles spinel LiMn2O4