From digital devices to electric vehicles, rechargeable lithium-ion batteries have been widely used in social life. However, due to the limited energy density of electrode materials based on the insertion mechanism, traditional Li-ion batteries are gradually unable to meet the growing energy demands of emerging fields.
As a "close relative" of lithium-ion batteries, lithium metal batteries have a very promising future. Compared with lithium-ion batteries, they can not only store more energy, charge faster, but also weigh less. But at present, the commercial use of lithium metal batteries is still limited, one of the main reasons is the formation of dendrites.
Dendritic crystals are commonly found in the anode of lithium batteries. Briefly, the main reason is that during the process of discharging and charging the battery, lithium ions may be unevenly distributed on the electrode, which will cause some dendrite-like particles to form on the anode. structure, when the dendritic structure grows longer and longer, it may cause a battery short circuit or even a fire. How to prevent or slow down the formation of dendrites has become a "pain point" for effectively solving the degradation and failure of lithium metal batteries.
To solve this problem, Stanford researchers have developed a mathematical model that integrates the physical and chemical processes that form dendrites. When replaced with a new electrolyte with certain properties, lithium ions move through the electrolyte between the two electrodes of the battery, slowing or even completely preventing dendrite growth.
Specifically, new strategies for electrolyte design called for by this research include understanding the material's anisotropy. The anisotropy of a material means that the material has different performance indicators in two directions that are perpendicular to each other. For example, the tensile strength of many materials in the transverse and longitudinal directions is significantly different, which means that they behave in different directions. different properties.
Wood is a typical anisotropic material, and its grain is very directional, and many times you can see the lines of the wood, not the grain. In the case of anisotropic electrolytes, these materials can fine-tune the complex interplay between ion transport and interfacial chemistry, preventing dendrite formation.
In addition, the researchers identified another method concentration on the battery separator -- a thin film that prevents the electrodes at both ends of the battery from contacting and shorting out. According to the developed new separator with porosity, lithium ions can pass back and forth in the electrolyte in an anisotropic manner.
Based on these breakthroughs, it is expected to build a "digital avatar" mature lithium metal battery system (DABS) in the future.
