Recently, the department of energy's Pacific northwest national laboratory of Liu Bin (Bin Liu), Dr Ji-guang Zhang (Ji Guang Zhang) and Dr Xu Wu (Wu Xu), Dr. (corresponding author) on the Cell Press's new flagship journal Joule energy online published titled "Advancing Lithium Metal Batteries" prospective review paper. The author introduces the current world lithium protection within recent important advances, and put forward the lithium metal stabilization and the future research direction of the development of the lithium battery and its prospect.
The author summarizes three different lithium battery: from the traditional embedded the anode of lithium battery and lithium metal composition, consisting of lithium sulfur positive electrode and metal lithium sulfur batteries, and composed of air cathode and lithium metal lithium air batteries. As shown in figure 1, they each have different lithium battery charge and discharge reaction and metal faces many challenges. In lithium sulfur and lithium air batteries, lithium metal will also face polysulphide and superoxide anion free radicals attack, lithium metal leads to more side effects. Therefore, based on relative to the embedded in the anode of lithium battery of lithium metal instability problem of sulfur in the lithium battery and lithium air effectively protect lithium metal will be more complex and difficult. However, the high energy density of lithium sulfur and lithium air batteries are almost completely relies on the utilization of lithium metal anode, so to achieve the protection of lithium metal good is the key of the next generation battery technology development. Author refining summarized in inhibition of lithium metal dendrite growth, stable lithium metal and lithium metal anode and electrolyte interface structure optimization of the iconic important research progress, as shown in the figure below.
The author thinks that although there are numerous studies have shown that lithium dendrite growth can be suppressed to a certain extent, but if you want to apply lithium metal anode promote industrialization level, there are still many problems worth careful consideration and solved. More importantly, the author also gives the lithium battery and lithium metal protection for the future development is the development direction of guidance:
1) more accurately understand the nuances of the SEI film morphology and formation mechanism, composition and features. Such as researchers can using transmission electron microscopy, atomic force microscopy, Raman spectroscopy, etc. Among them, the characterizations of in situ with observations will more help to give a more accurate judgment.
2) through the formation of surface film with high ionic conductivity to block lithium metal and the electrolyte contact directly, so as to improve the stability of lithium metal and the electrolyte. Also, find out the optimization of electrolyte of lithium salts and the solvent coordination relationships, reduce free (i.e., not ligand) lithium salt anions and solvent quantity, improving the electrolyte of lithium metal, polysulphide and superoxide anion free root of stability.
3) should not be limited to the simple lithium lithium battery or lithium battery copper symmetrically to assess its stability, should be mentioned in the above three kinds of the battery in the comprehensive assessment of the stability of lithium metal. And, in the performance evaluation should use limited dosage of lithium, a small amount of electrolyte, high lithium metal capacity utilization (such as 3 ~ 4 mah/cm2) charging current density and high (> 1 ma/cm2).
4) no lithium dendrite growth must be achieved through synergy optimization of each battery components, thus greatly reduce the battery safety risk.
5) lithium in circulation volume change will cause the death of the play in the process of the formation of lithium, also can cause than work for integration of the battery and lithium dendrite more obvious direct impact, so in the process of circulation effectively inhibited the volume of lithium metal and morphology changes also appear particularly important. Design some 3 d structure of the base material contain lithium metal to limit the volume change of it is an effective method.
6) according to the actual capacity demand of different lithium battery, can control the lithium metal anode sets in fluid on the amount of deposit. In addition, through the three dimensional printing technology, mechanical technology and lithography technology can design 2 d or 3 d metals such as collection of fluid in order to make the lithium metal orderly deposition in advance design good model.
7) with low-cost simplified lithium protection method to replace the most complicated and the high cost of method, for example: in situ electrochemical pretreatment method in thin protective layer is formed on the lithium metal, used in the subsequent cycle to provide continuous protection of lithium battery.
8) for the production of lithium metal sheet processing, packaging, storage, transportation and battery packaging design a set of feasible special methods to ensure that the "through-train" type of lithium metal protection. Among them, the high stability of lithium metal pole piece outer packing material should have high demand.