Shenzhen Advanced Institute put forward new ideas on ion superconducting mechanism and solid electrolyte design

[ Instrument Network Instrument R & D ] On March 6, Lu Ziheng, assistant researcher at the Photonic Information and Energy Materials Research Center of the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, and Francesco Ciucci, a professor of mechanical engineering at the Hong Kong University of Science and Technology, proposed a new mechanism for ion superconductivity in solid electrolyte And designed a new low-dimensional antiperovskite solid electrolyte.

A solid electrolyte (solid electrolyte in situ) is able to move (charged matter) a solid by an electric field applied from the outside. Instead, the movement of ions can be used to absorb energy. Used as a power generation material for solid oxide fuel cells and as an electrode conductor for electrolytic capacitors.

In metals and semiconductors, current is mainly due to the movement of electrons, while in solid electrolytes, current is mainly due to the movement of ions. Moving charged particles are similar to ionic electrolytes in solution. The medium where ions move is solid at low speed, and conductive at low temperature is low.

The rapid transmission of solid cations is essential for a variety of solid-state devices, the most prominent of which is the solid-state battery. As a next-generation high-specification and high-safety energy storage technology that is expected to replace the existing lithium-ion batteries, solid-state batteries have received widespread attention from the academic and industrial communities. Currently, one of the core pain points of solid-state batteries is the low ionic conductivity of solid-state electrolytes, which limits the output power of solid-state batteries at room temperature, and therefore limits the practical use of solid-state batteries. At present, designing solid electrolyte materials with high ionic conductivity is one of the core topics of solid state ionics, and it is also a recognized problem.

Solid-state batteries are a battery technology. Unlike lithium-ion batteries and lithium-ion polymer batteries that are commonly used today, a solid-state battery is a battery that uses a solid electrode and a solid electrolyte.

Because the scientific community believes that lithium-ion batteries have reached their limits, solid-state batteries have been regarded as batteries that can inherit the status of lithium-ion batteries in recent years. Solid-state lithium battery technology uses glass compounds made of lithium and sodium as conductive materials, replacing the electrolyte of previous lithium batteries, and greatly improving the energy density of lithium batteries.

Inspired by the low-dimensional organic-inorganic inverse perovskite in the field of photovoltaics, the team proposed a design idea of ​​constructing different-dimensional antiperovskite crystal solid electrolyte layer by layer from the basic "structural unit". The team's research found that phonon softening in low-dimensional structures can cause rapid transport of lithium ions. Based on this, the team predicts that two-dimensional and below two-dimensional perovskites not only have extremely high stability, but also have an ionic conductivity close to that of a liquid electrolyte (10 mS cm-1). The team is currently actively synthesizing such materials and has made some progress.

Electrical conductivity is highly correlated with temperature. The conductivity of metals decreases with increasing temperature. The conductivity of a semiconductor increases with increasing temperature. In a range of temperature values, the conductivity can be approximated as being proportional to temperature. In order to compare the conductivity of a substance at different temperature conditions, a common reference temperature must be set. The correlation between conductivity and temperature can often be expressed as the slope of the conductivity vs. temperature plot.

The design ideas for the stepwise construction of solid electrolytes from structural templates and the ionic superconducting mechanism induced by phonon softening have important guiding effects on the design of key materials in next-generation solid-state batteries.

Source: Encyclopedia, Shenzhen Institute of Advanced Technology