Scientists develop new electrolyte: greatly improve the performance of lithium metal batteries

On June 22, according to foreign media reports, a new study published by researchers at Stanford University in "Nature Energy" shows how a new battery electrolyte technology can improve the performance of lithium metal batteries. performance.

Lithium metal batteries are lighter than lithium ion batteries and can deliver twice the energy of lithium ions for the same weight. Therefore, lithium metal batteries are a more promising battery technology for electric vehicles and other devices.

However, lithium dendrite growth is one of the fundamental problems affecting the reliability and stability of lithium metal batteries. The growth of lithium dendrites can lead to the instability of the electrode and electrolyte interface of lithium-ion batteries during cycling, which continuously consumes the electrolyte and leads to irreversible deposition of metallic lithium, resulting in low coulombic efficiency due to the formation of dead lithium. In addition, the formation of lithium dendrites can even pierce the separator, resulting in a short circuit inside the lithium-ion battery, resulting in a thermal runaway of the battery and a combustion explosion.

According to the researchers, the electrolyte is a key issue in preventing lithium dendrite growth, so we wanted to use organic chemistry to rationally design and fabricate new, stable electrolytes for these batteries.

In the study, the researchers added fluorine atoms to a commercial common electrolyte and used its ability to attract electrons to create a new molecule that would allow lithium metal anodes to function well in the electrolyte. The result was a new synthetic compound, FDMB for short. Fluorine is a widely used element in lithium battery electrolytes, so FDMB can be mass-produced and very cheap.

The researchers then tested the new electrolyte in lithium metal batteries. It was found that after 420 charge-discharge cycles, the experimental battery still maintained 90% of its initial charge. Previously, ordinary lithium metal batteries were unusable after about 30 cycles of discharge.

In addition, the researchers also measured the coulombic efficiency (discharge efficiency) of lithium ions during charging and discharging. In the case of half cells, the Coulombic efficiency was 99.52%; in the case of full cells, the Coulombic efficiency was 99.98%.

The researchers said that the study brought hope for the application of lithium metal batteries and new hope for the development of next-generation electric vehicles.