Construction of composite lithium with high adhesion work and fast ionic conductivity by black phosphorus for solid-state lithium batteries

Li6.4La3Zr1.4Ta0.6O12 (LLZTO) based solid-state lithium metal batteries (SSLMBs) have a broad application prospect because of the nonflammable nature as well as the high energy density. However, the loose contact and the contact degradation of Li/LLZTO in the stripping process result in the serious lithium dendrites growth. Herein, these issues are addressed by a composite lithium anode (CLA), which is prepared through the reaction between black phosphorus and molten lithium. In comparison to pure lithium, a higher adhesion work (722.67 mJ m-2) and Li+ diffusion coefficient (2.45x10- 12 cm2 s-1) are achieved for CLA, thus assuring the intimate interfacial contact of CLA/LLZTO interface during the lithium stripping process. As a result, a small interfacial resistance of 3.7 Omega cm2, a high critical current density of 1.5 mA cm- 2, and extra-long cycle life of 8200 h at 0.3 mA cm- 2 are achieved for CLA symmetric cell at 25 degrees C. More importantly, the full cell coupled with high mass loading LiFePO4 cathode (10.6 mg cm-2) still shows a large discharge capacity of 156.3 mAh g-1 and cycles stably at 25 degrees C. This work provides an alternative approach to develop the long lifespan and high capacity of SSLMBs.