Li<sub>3</sub>N-Modified Garnet Electrolyte for All-Solid-State Lithium Metal Batteries Operated at 40 °C.

Xu, Henghui; Li, Yutao; Zhou, Aijun; Wu, Nan; Xin, Sen; Li, Zongyao; Goodenough, John B · Nano Lett · 2018

basic_science · Level V

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Abstract

Lithium carbonate on the surface of garnet blocks Li<sup>+</sup> conduction and causes a huge interfacial resistance between the garnet and electrode. To solve this problem, this study presents an effective strategy to reduce significantly the interfacial resistance by replacing Li<sub>2</sub>CO<sub>3</sub> with Li ion conducting Li<sub>3</sub>N. Compared to the surface Li<sub>2</sub>CO<sub>3</sub> on garnet, Li<sub>3</sub>N is not only a good Li<sup>+</sup> conductor but also offers a good wettability with both the garnet surface and a lithium metal anode. In addition, the introduction of a Li<sub>3</sub>N layer not only enables a stable contact between the Li anode and garnet electrolyte but also prevents the direct reduction of garnet by Li metal over a long cycle life. As a result, a symmetric lithium cell with this Li<sub>3</sub>N-modified garnet exhibits an ultralow overpotential and stable plating/stripping cyclability without lithium dendrite growth at room temperature. Moreover, an all-solid-state Li/LiFePO<sub>4</sub> battery with a Li<sub>3</sub>N-modified garnet also displays high cycling efficiency and stability over 300 cycles even at a temperature of 40 °C.