All-Solid Battery Interlayer Reduces Resistance

A buffer layer comprising a metal element (such as Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Sb, or their alloys) is introduced between the lithium metal negative active material and the solid electrolyte. This intermediary buffer layer prevents direct contact and side reactions between lithium metal and the solid electrolyte, thereby reducing interfacial resistance and improving lifespan while maintaining the high capacity density of lithium metal.

The buffer layer acts as a protective intermediary between lithium metal and the solid electrolyte, preventing harmful side reactions and lithium metal deposition that could lead to short circuits. This allows the system to maintain high energy density from lithium metal while eliminating the associated safety risks.

The invention merges the safety advantages of carbonaceous materials (or absence of flammable organic solvents) with the high capacity density of lithium metal. By using lithium metal as the negative active material in an all-solid battery configuration without flammable organic solvents, and adding a protective buffer layer, the system achieves both high safety and high capacity density simultaneously.

The buffer layer serves as a simple yet effective intermediary structure between the negative active material and solid electrolyte. While it does add a layer to the structure, the buffer layer can be formed by straightforward methods such as sputtering, evaporation, or chemical deposition, and uses common metal elements, thus minimizing the increase in device complexity while delivering significant improvements in interfacial resistance and cycle stability.