Energy storage systems with high energy density have been strongly pursued. The current commercial lithium (Li) ion batteries (LIBs) have achieved impressive advance since released by Sony Corporation in 1991 and dominate a chunk of the portable electronic and electric vehicle markets. However, the practical energy density of LIBs is approaching their theoretical limits with current intercalation chemistry. In light of the ever-growing demands for even higher energy density storage, Li metal batteries (LMBs) have been revisited. While replacing the graphite anode of LIBs with Li metal of LMBs, the theoretical energy density of LMBs can be significantly improved due to its ultrahigh specific capacity (3860 mAh g-1) and the lowest redox potential (-3.04 V vs. the standard hydrogen electrode). However, uncontrolled lithium dendrites and infinite volume change during repeated plating/stripping cycles hinder the practical applications of Li metal battery immensely.
Researchers in Tsinghua University and Beijing Institute of Technology proposed a house-like Li anode (housed Li) to circumvent the above issues. The house matrix was composed of carbon fiber matrix and affords a stable structure to relieve the volume change. An artificial solid electrolyte layer was formed on composite Li metal, just like the roof of a house, which facilitates uniform Li ions diffusion and serves as a physical barrier against electrolyte corrosion. With the combination of solid electrolyte layer and matrix in the composite Li metal anode, both dendrite growth and volume expansion are remarkably inhibited. The housed Li | LiFePO4 batteries exhibited over 95% capacity retention after 500 cycles at 1.0 C in coin cell and 85% capacity retention after 80 cycles at 0.5 C in pouch cell.
The rationally combination of solid electrolyte layer protection and housed framework in one Li metal anode is a breakthrough on the design principle of a safe and long-lifespan Li metal anode for Li metal batteries. This work is expected to provide a practical anode for next-generation rechargeable batteries. The paper describing this work was published on Nov. 30 in Journal of Energy Chemistry.
This work was supported by the National Key Research and Development Program (2016YFA0202500, 2015CB932500, and 2016YFA0200102), the National Natural Science Foundation of China (21676160, 21825501, 21805161, and 21808125), and China Postdoctoral Science Foundation (2017M620773, 2018M631480, and BX201700125).