Solid-state batteries (SSBs) remain far from mainstream adoption in battery energy storage systems (BESS), as their potential benefits have yet to outweigh high costs, manufacturing challenges and limited commercial experience. Although they promise improved safety, higher energy density and potentially longer lifetimes, grid-scale storage has different priorities from electric vehicles. For BESS applications, affordability, cycle life, reliability, safety and bankability are more important than energy density, making established lithium iron phosphate (LFP) batteries difficult to displace.
SSBs also also face challenges related to uneven lithium plating and stripping during operation, which can cause interfacial instability, void formation and lithium (Li) filament growth. These effects can accelerate degradation, increase the risk of internal short circuits and compromise the long-term reliability required for stationary energy storage applications.
To address this challenge, researchers at South Korea’s Dongguk University have developed an anode-free all-solid-state battery (ASSB) in which Li from the cathode is deposited directly onto a bare current collector during the initial charging cycle, forming an anode in situ. “This architecture enhances volumetric energy density and simplifies fabrication, particularly for thin-film batteries. However, it is vulnerable to Li loss caused by uneven deposition, electrically isolated ‘dead’ lithium, or loss of contact with the solid electrolyte during stripping, compromising battery stability and capacity,” they explained.
The proposed innovation relies on what the research group describes as an anode-less thin-film battery platform using an ultrathin tin/carbon (Sn/C) interlayer, which is intended to eliminate the need for a conventional lithium-metal anode during manufacturing. Instead, a very thin coating of tin and carbon is applied to the anode-side current collector to control how lithium deposits during charging.
“Our interlayer acts as a seed for Li nucleation, promoting uniform Li plating and reducing Li loss and improving the reversibility of repeated charging and discharging,” said lead author Hyun-Suk Kim.
The battery prototype features a modified copper current collector coated with ultrathin layers of tin and carbon, an architecture the researchers identified as the most effective after evaluating several metal-based, carbon-based and hybrid coatings. Their experiments showed that the Sn/C combination offered superior control over Li deposition while improving stability at the electrode interface.
The improvement stems from the different functions of the two materials. Tin provides favorable sites for lithium to accumulate by lowering the energy required to initiate deposition, while carbon helps distribute the deposited lithium more evenly. This combination limits irregular growth and supports a more stable interface during repeated charging and discharging.
To further improve performance, the team added a small amount of metallic Li to the coated current collector before cycling. This “prelithiation” step creates a lithium reserve intended to compensate for irreversible losses during early operation, addressing a key limitation of anode-free battery designs.
The researchers assembled the modified current collector (Cu@Sn/C) with a lithium vanadium oxide (LVO) cathode and a lithium phosphorus oxynitride (LiPON) solid electrolyte. The resulting cell, measuring only 2.77 micrometers thick, delivered a volumetric energy density of 235.13 Wh/L at the 100th cycle, under a reported cycling rate of 0.01 C.
Microscopic analysis also provided insight into the battery’s stability. During the first lithium deposition, a three-dimensional structure containing tin and lithium–tin alloy developed within the interlayer. This structure helped accommodate the physical changes associated with subsequent cycling, reducing disruption at the interface and supporting more consistent battery operation.
“Our approach shows how interface engineering and lithium-inventory management can improve anode-less thin-film batteries,” said Kim. “This approach could support the development of ultrathin batteries for wearable electronics, IoT sensors, and medical devices, as well as scalable anode-less ASSBs for industrial-scale power.”
The novel SSB concept was presented in “Pushing Energy Density Limits: Anode-Less Solid-State Battery Integrated With Amorphous Lithium Vanadium Oxide Thin-Film Cathode,” published in Advanced Energy Materials.
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