Universal lithiophilic interfacial layers towards dendrite-free lithium anodes for solid-state lithium-metal batteries

Solid-state lithium-metal-batteries (SSLMBs) using garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) as the solid electrolyte are expected to conquer the safety concerns of high energy Li batteries with organic liquid electrolytes owing to its nonflammable nature and good mechanical strength. However, the poor interfacial contact between the Li anode and LLZTO greatly restrains the practical applications of the electrolyte, because large polarization, dendritic Li formation and penetration can occur at the interfaces. Here, an effective method is proposed to improve the wettability of the LLZTO toward lithium and reduce the interfacial resistance by engineering universal lithiophilic interfacial layers. Thanks to the in-situ formed lithiophilic and ionic conductive Co/Li2O interlayers, the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential, ultra-low areal specific resistance (ASR, 12.3 X cm2), high critical current density (CCD, 1.1 mA cm-2), and outstanding cycling performance (1696 h at a current density of 0.3 mA cm-2) at 25 degrees C. Besides, the solid-state Li/CoO-LLZTO/LFP cells deliver an excellent electrochemical performance with a high coulombic efficiency of -100% and a long cycling time over 185 times. Surprisingly, the high-voltage (4.6 V) solid state Li/CoO-LLZTO/Li1.4Mn0.6Ni0.2Co0.2O2.4 (LMNC622) batteries can also realize an ultra-high specific capacity (232.5 mAh g-1) under 0.1 C at 25 degrees C. This work paves an effective way for practical applications of the dendrite-free SSLMBs. (c) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

This study proposes an effective method to improve the wettability of LLZTO towards lithium and reduce the interfacial resistance by engineering lithiophilic interfacial layers, thereby enhancing the performance of solid-state lithium-metal batteries. Experimental results demonstrate that the performance of symmetric Li/CoO-LLZTO/Li batteries can be improved by the unique layers formed between LLZTO and lithium, showing smaller overpotential and higher cycling performance.