Metal-ligand coordination induced rapid Li⁺ transport kinetics through bidirectional anchoring strategy

The unstable interfacial contact and slow Li⁺ transport at the side of cathode have been two major challenges for practical application of garnet-based solid-state batteries (SSBs). In this work, a strategy of metal-ligand coordination induced rapid Li⁺ transport kinetics through bidirectional anchoring is proposed to address aforementioned issues by decorating the cathode with Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) nanoparticles and stabilizing the interface with succinonitrile-based interlayer (SL). The strong metal-ligand coordination of the -CN in SL with the LLZTO solid-state electrolytes and the LiCoO₂ (LCO)@LLZTO composite cathode enables an intimate contact at the atomic scale, constructing bidirectional channels of fast Li⁺ transport at the interface. Additionally, LLZTO nanoparticles within the composite cathode establish three-dimensional (3D) channels of fast Li⁺ transport. The synergistic effect of the bidirectional channels of fast Li⁺ transport at the interface and 3D channels of Li⁺ transport at internal cathode achieves rapid Li⁺ transport kinetics at the cathode side. As a result, a high capacity retention of 80.6 % after 700 cycles at 0.1 C is achieved for the LCO@LLZTO(SL)|LLZTO|Li batteries (3.0-4.2 V, 3 mg·cm^-2). It also exhibits excellent cycling performance even at high voltages of 3.0-4.4 V. This work offers a new possibility for fabricating ultra-stable SSBs.