Hundred-micron-sized all-solid-state Li secondary battery arrays embedded in a Si substrate

Abstract

Fabrication and charge/discharge behaviors of all-solid-state Li secondary battery arrays embedded into three Si trenches of $\text{200×100\hspace{0.17em}μ}{\mathrm{m}}^2$ in area and $\text{0.5∼2.0\hspace{0.17em}μ}\mathrm{m}$ in depth are presented. The battery arrays in a Si wafer, consisting of multiple layers (Al current ${\mathrm{collector/Li/SiO}}_2\text{–15\hspace{0.17em}}\mathrm{at.}\mathrm{ \%}{\mathrm{P}}_2{\mathrm{O}}_5/{\mathrm{LiMn}}_2{\mathrm{O}}_4/\mathrm{polycrystalline}$ silicon current collector), are prepared by combining a sol-gel spin-coating method and Si very-large-scale integration technologies. Porous spin-on glass $({\mathrm{SiO}}_2\text{–15\hspace{0.17em}}\mathrm{at.}\mathrm{ \%}{\mathrm{P}}_2{\mathrm{O}}_5)$ is adopted as an electrolyte layer, in which spatial paths for ${\mathrm{Li}}^{+}$ ions are artificially introduced into the glass. Each active battery area is isolated with double insulating walls $({\mathrm{Si}}_3{\mathrm{N}}_4/{\mathrm{SiO}}_2\mathrm{).}$ The battery arrays demonstrate a constant capacity of $\text{∼9.2\hspace{0.17em}μ}{\mathrm{A h cm}}^{\text{−2}}$ at $\text{∼3.6\hspace{0.17em}}\mathrm{V}$ up to 100 cycles.