MoS₂ thin films extend lifespan of anode-free solid-state batteries by seven-fold

South Korean researchers have developed a technology that improves the lifespan of next-generation anode-free all-solid-state batteries (AFASSBs) by seven-fold using a cost-effective two-dimensional material.

A collaborative team led by Dr. Ki-Seok An and Dr. Dong-Bum Seo of the Korea Research Institute of Chemical Technology (KRICT), along with Prof. Sangbaek Park’s group at Chungnam National University successfully enhanced the durability of AFASSBs by applying a molybdenum disulfide (MoS₂) sacrificial layer grown via metal–organic chemical vapor deposition (MOCVD) onto stainless steel (SUS) current collectors.

The study was published in Nano-Micro Letters.

Conventional lithium-ion batteries use liquid electrolytes and can suffer from lithium dendrite growth during charging—especially due to uneven lithium deposition on the anode surface—which may pierce the separator and cause short circuits or thermal runaway.

Solid-state batteries (SSBs), which replace flammable liquid electrolytes with solid-state electrolytes (SEs), offer enhanced safety, higher energy density, and stable performance at low temperatures.

Going a step further, AFASSBs eliminate the anode entirely during fabrication. Instead, lithium ions migrate from the cathode during the initial charge and plate on the current collector, forming a lithium layer. This structure maximizes energy density by reducing cell volume. However, repeated lithium plating/stripping at the SE–current collector (CC) interface often leads to interfacial instability and reduced cycle life.

Although noble metal coatings (e.g., Ag, In) have been used to stabilize the interface, their high cost and complex processing hinder commercialization.

To overcome these challenges, the researchers applied low-cost MoS₂ nanosheet thin films to the SUS CCs using MOCVD. During cycling, MoS₂ undergoes a conversion reaction with lithium to form Mo metal and lithium sulfide (Li₂S), which act as a lithiophilic interfacial layer. This interlayer helps suppress dendritic lithium growth and improves interfacial stability.

In tests, batteries with MoS₂-coated CCs demonstrated stable operation for over 300 hours, whereas cells using bare SUS short-circuited after about 95 hours—a 3.2-fold improvement. Full cells with MoS₂ layers also achieved 1.18 times higher initial discharge capacity (136.1 → 161.1 mAh/g) and seven-fold improved capacity retention (8.3% → 58.9% after 20 cycles).

While still at an early stage of development, the research team anticipates practical implementation by 2032. They emphasized the significance of replacing noble metals with low-cost MoS₂ in advancing AFASSBs.

KRICT President Young-Kuk Lee stated, “This is a core next-generation technology that could accelerate the commercialization of all-solid-state batteries across various applications.”