Enabling an electron/ion conductive composite lithium anode for solid-state lithium-metal batteries with garnet electrolyte

The use of Li anode is critical for the energy density of solid-state Li-metal batteries (SSLMBs) to surpass that of lithium-ion batteries. However, the practical applications are hampered by the large interfacial resistance and poor physical contact at the solid-state interface, as well as dendrite issues and volume changes of Li anode. Here, a composite lithium anode with continuous electron/ion conductive networks is fabricated, which shows a significant improvement in wettability towards garnet-type Li6.4La3Zr1.4Ta0.6O12 electrolytes. The intimate interface and its high charge-transfer kinetics of composite Li anode endows the symmetric cell a small overpotential (45 mV) at 0.3 cm−2, ultra-low interfacial resistance (∼ 2.0 Ω cm2), high critical current density (1.1 mA cm−2), and outstanding cycling performance (>3000 h at 0.1 mA cm−2) at 25 °C. The SSLMB paired with LiFePO4 delivers a high discharge specific capacity of 161.7 mAh g−1 at 0.1 C, good cycle performance of 100 cycles with capacity retention of 80%. Moreover, the NMC811-based SSLMB can also realize a high capacity of 219.5 mAh g−1, superior rate capability and cyclic stability. This work lays the foundation to develop composite Li anodes for practical applications of SSLMBs with high performance.