Nano-vault architecture mitigates stress in silicon-based anodes for lithium-ion batteries

Nanomaterials undergoing cyclic swelling-deswelling benefit from inner void spaces that help accommodate significant volumetric changes. Such flexibility, however, typically comes at a price of reduced mechanical stability, which leads to component deterioration and, eventually, failure. Here, we identify an optimised building block for silicon-based lithium-ion battery (LIB) anodes, fabricate it with a ligand- and effluent-free cluster beam deposition method, and investigate its robustness by atomistic computer simulations. A columnar amorphous-silicon film was grown on a tantalum-nanoparticle scaffold due to its shadowing effect. PeakForce quantitative nanomechanical mapping revealed a critical change in mechanical behaviour when columns touched forming a vaulted structure. The resulting maximisation of measured elastic modulus (similar to 120GPa) is ascribed to arch action, a well-known civil engineering concept. The vaulted nanostructure displays a sealed surface resistant to deformation that results in reduced electrode-electrolyte interface and increased Coulombic efficiency. More importantly, its vertical repetition in a double-layered aqueduct-like structure improves both the capacity retention and Coulombic efficiency of the LIB. Lithiation of anodes during cycling of lithium-ion batteries generates stresses that reduce operation lifetime. Here, a composite silicon-based anode with a nanoscale vaulted architecture shows high mechanical stability and electrochemical performance in a lithium-ion battery.

Automated summary

An optimized silicon-based building block for lithium-ion battery anodes was fabricated using a ligand- and effluent-free cluster beam deposition method, resulting in improved mechanical stability and electrochemical performance. The columnar amorphous-silicon film grown on a tantalum-nanoparticle scaffold displayed a vaulted nanostructure that enhanced elastic modulus and Coulombic efficiency. The vaulted architecture showed high resistance to deformation, leading to reduced electrode-electrolyte interface and improved capacity retention in the lithium-ion battery.