Strategies in Structure and Electrolyte Design for High‐Performance Lithium Metal Batteries

Abstract

Lithium metal is the “holy grail” anode for next‐generation high‐energy rechargeable batteries due to its high capacity and lowest redox potential among all reported anodes. However, the practical application of lithium metal batteries (LMBs) is hindered by safety concerns arising from uncontrollable Li dendrite growth and infinite volume change during the lithium plating and stripping process. The formation of stable solid electrolyte interphase (SEI) and the construction of robust 3D porous current collectors are effective approaches to overcoming the challenges of Li metal anode and promoting the practical application of LMBs. In this review, four strategies in structure and electrolyte design for high‐performance Li metal anode, including surface coating, porous current collector, liquid electrolyte, and solid‐state electrolyte are summarized. The challenges, opportunities, perspectives on future directions, and outlook for practical applications of Li metal anode, are also discussed.

Constructing nitrided interfaces for stabilizing Li metal electrodes in liquid electrolytes

“…16,[25][26][27][28] The inner layer of the SEI (close to Li metal) consists of inorganic components such as lithium oxide (Li 2 O), lithium fluoride (LiF), and lithium carbonate (Li 2 CO 3 ), while the outer layer of the SEI (close to the electrolyte) mainly consists of organic components such as polylephins and semicarbonates (Figure 1c). 25,29,30 The SEI layer is electrically non-conductive but ionically conductive, so that it can block the electron transport in the Li/electrolyte interface and stop the further decomposition of electrolyte while Li + diffuses through the layer. 16,26 Unlike graphite which stores Li + in its lattice with acceptable volumetric changes (~ 12%), Li metal anode accommodates Li + at the Li/electrolyte interface, leading to unlimited volumetric changes during Li plating/stripping processes.…”

A LiPF6-LiFSI Blended-Salt Electrolyte System for Improved Electrochemical Performance of Anode-Free Batteries

“…In addition, dendritic Li growth and volume fluctuation during cycling are fatal issues that cause poor cycle and safety problem. To circumvent these concerns, several researches have mainly focused on designing functional electrolytes [21,22]. However, although the electrolyte approach verified the usefulness of controlling deposition morphology of Li and chemical composition of SEI layer, most of electrolytes are based on the ether-solvent, and thus it is indeed vulnerable to stability and oxidation at high voltage operation.…”

Polyzwitterions Functionalized Nafion Barrier Toward High Performance Lithium‐Sulfur Batteries

“…The dendrites will lower the Li/Li + transference rate, penetrate the separator and result in a short battery lifespan. [6,7] On the other hand, the shuttle effect triggered by the solution of lithium polysulfides (LiPS) in the electrolyte is another issue, which will lead to low sulfur utilization, and the quick decrease of cycling stability. [8][9][10] In the past several years, a variety of strategies have been developed to solve the above issues, such as constructing carbon matrix for both sulfur cathode and lithium anode, [11][12][13][14][15][16] employing binders that strongly anchor of LiPS during cycling, [17] adding additives in the organic electrolyte to harmonize dendrite formation and LiPS diffusion, [18][19][20][21] and engineering muti-functional separator for dendrite inhibition and LiPS blocking.…”

“…On the one hand, the uncontrollable dendrite growth issue incessantly occurs in lithium metal batteries. The dendrites will lower the Li/Li + transference rate, penetrate the separator and result in a short battery lifespan [6,7] . On the other hand, the shuttle effect triggered by the solution of lithium polysulfides (LiPS) in the electrolyte is another issue, which will lead to low sulfur utilization, and the quick decrease of cycling stability [8–10] …”