Professor Liping Wang from the University of Electronic Science and Technology of China said: "Through this strategy, the rational design of the host and electrolyte can solve the volume change and dendrite problems, and provide a broader prospect for the fabrication of lithium metal anodes."

Lithium metal is considered as a promising anode for next-generation batteries due to its ultrahigh theoretical capacity, extremely low electrode potential, and low density. However, Li metal suffers from uncontrollable Li dendrite growth, side reactions, and relatively infinite volume changes. These problems will reduce the efficiency of the battery, shorten the cycle life of the battery, and may even cause safety hazards such as short circuits.

For a long time, researchers have been exploring different methods to alleviate the dendrite growth and volume expansion problems, such as constructing three-dimensional composite lithium anodes, optimizing electrolyte composition, applying artificial interfacial films and solid electrolytes, etc. Three-dimensional hosts are the most promising approach to address volume expansion and dendrite growth. In lithium metal anodes, carbon-based materials are ideal host candidates due to their multiple advantages such as light weight, high electrical conductivity, pore structure, and stable electrochemical/chemical performance. But Professor Wang said: "Although carbon-based hosts have many advantages, they cannot completely solve the problems of volume expansion and dendrite growth."

Recently, researchers have explored the modification of carbon materials with lithiophilic species (such as Zn, ZnO, Al, Sn, Si, Ag, and Mg) and the development of suitable electrolytes as an effective way to enhance the three-dimensional performance. host material.  "However, the lithium deposition behavior and its intrinsic mechanism have not been systematically analyzed," said Prof. Wang.

In order to better understand the structure-activity relationship, discover the lithium deposition behavior and its internal mechanism, and point out the direction for the development of high-performance carbon-based host electrodes, the team conducted in-depth research. The researchers systematically investigated the lithium deposition behavior of hydrocarbon electrodes under different surface modifications and electrolytes using optical microscopy and scanning electron microscopy. Lithium does not spontaneously deposit into carbon pores, the researchers found. This largely depends on the carbon surface, current density, areal capacity, and electrolyte.

Therefore, the team developed a silver-containing lithiophilic modified commercial hard carbon as a stabilizing host. The introduction of lithiophilic sites was found to guide dendrite growth and suppress volume expansion. In addition, the researchers found that locally high-concentration electrolytes proved to be more compatible with lithium, which can optimize the lithium deposition morphology and prevent it from forming dendrites. As a result, the Ag/hydrocarbon electrode located in a local high-concentration electrolyte achieves a uniform and dendrite-free Li deposition morphology during cycling and exhibits good long-term cycling efficiency (over 316 cycles).

The team concluded that although porous carbon has theoretical space to accommodate lithium, lithium ions do not deposit into the intended pores because lithium atoms prefer to aggregate in an explosive growth mode that is sufficient to accommodate carbon particles. The researchers also found that surface modification of the carbon lowered the nucleation barrier, thereby partially mitigating lithium deposition. However, since this is the Li–Li deposition behavior after Li is deposited onto the lithophile, it is not efficient. The team found that dendrite-free lithium deposition can be more efficiently achieved using locally high-concentration electrolytes.