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

Engineering the universal metal/Li 2 O lithiophilic interfacial layers can effectively improve the wettability of LLZTO toward lithium and reduce the interfacial resistance, finally endowing a dendrite-free lithium anode for solid-state lithium-metal batteries. Solid-state lithium-metal batteries (SSLMBs) using garnet Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (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/Li 2 O interlayers, the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential, ultra-low areal specific resistance (ASR, 12.3 Ω cm 2 ), 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 °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/Li 1.4 Mn 0.6 Ni 0.2 Co 0.2 O 2.4 (LMNC622) batteries can also realize an ultra-high specific capacity (232.5 mAh g −1 ) under 0.1 C at 25 °C. This work paves an effective way for practical applications of the dendrite-free SSLMBs.