Multidimensional Design of Li Hosts for Li–Metal Batteries: Limitations and Future Directions

Li–metal batteries (LMBs) have been attracting enormous attention due to their superior performance and high theoretical energy density compared to conventional Li-ion batteries (LIBs). However, due to the uncontrollable Li dendrite growth, safety issues such as internal short circuits arise, which become more pronounced as the cell size increases or the operating conditions become harsh up to practical levels. Additionally, under high Li plating and stripping capacities, severe changes in anode thickness can lead to stability issues, and using a thick Li anode to ensure long-term cycling stability is not suitable for achieving high energy density in LMBs. As one of the strategies to address this problem, multidimensional conductive Li hosts with high surface areas have been investigated, as these structures can store Li inside the host framework, thereby mitigating volume changes during cycling. In this context, this review introduces recent strategies from a material perspective that have been conducted to form the host backbones using metals, carbon, and their hybrids. Then, we address structural design strategies to control the Li growth direction and stabilize the interface, and finally, we suggest host design insights considering energy densities that surpass those of LIBs to maximize the advantages of LMBs with Li hosts from a commercialization perspective. We hope that this review can motivate battery researchers to pave the way for the design of advanced Li hosts for high-performance and safe LMBs in the near future.