Room-Temperature Solid-State Lithium-Ion Battery Using a LiBH₄-MgO Composite Electrolyte.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Lithium borohydride (LiBH4) is a promising solid-state electrolyte for lithium-ion batteries.
• Pure LiBH4 exhibits low ionic conductivity at room temperature, limiting its practical application.
• High operating temperatures (120 °C) are typically required for adequate performance.

Purpose of the Study:

• To enhance the room-temperature ionic conductivity of LiBH4.
• To investigate the effect of MgO addition on LiBH4 properties.
• To evaluate the performance of a LiBH4-MgO composite electrolyte in a TiS2/Li all-solid-state battery.

Main Methods:

• Preparation of LiBH4-MgO composite materials with varying MgO concentrations.
• Measurement of ionic conductivity of the composite electrolytes.
• Electrochemical stability window determination.
• Fabrication and testing of TiS2/Li all-solid-state batteries using the composite electrolyte.

Main Results:

• The optimal composition, 53 v/v % MgO, significantly improved Li-ion conductivity to 2.86 × 10⁻⁴ S cm⁻¹ at 20 °C.
• The electrochemical stability window remained comparable to pure LiBH4 (approx. 2.2 V vs Li⁺/Li).
• Initial room-temperature battery tests showed rapid failure, but stable solid electrolyte interphase formation was achieved at 60 °C.
• Batteries operated for up to 30 cycles at room temperature with 80% capacity retention after initial high-temperature cycling.

Conclusions:

• Mixing LiBH4 with MgO effectively enhances its ionic conductivity at room temperature.
• A LiBH4-MgO composite electrolyte enables stable operation of TiS2/Li all-solid-state batteries after appropriate conditioning.
• The composite offers a viable pathway for developing practical solid-state lithium-ion batteries operating at ambient temperatures.