Ultrathin, large-area Li-metal anodes

Rethinking the starting lithium metal anodes — Lithium (Li) metal has been considered an ideal anode material due to its superiority: the lowest electronegativity (-3.04 V) and ultrahigh specific capacity (3,860 mAh/g). However, it has plagued the practical applications due to key challenges: Li dendrite formation and electrolyte depletion. In particular, the dendritic growth of Li metal during the electrochemical plating process results in a dynamic evolution of its morphology and surface chemical nature. Therefore, a full understanding of the interface chemistry between electrode and electrolyte, i.e., solid-electrolyte interphase (SEI), is paramount. With advanced analysis tools, multi-scale investigations from an atomic structure (below nano) to bulk (micron scale) are highly required to reveal the basic fundamentals inside.

Related publications 📝

• Sustaining surface lithiophilicity of ultrathin Li-alloy coating layers on current collector for zero-excess Li-metal batteries, Submitted (2024)

• Mechanothermal-milling-assisted removal of native passivation layer for refreshing lithium metal anodes, Submitted (2024)

• Regenerating native surface of lithium-metal electrodes via hydrohalic acid-assisted pre-halogenation, Chemical Engineering Journal (2024)

• Electrodeposition-guided pre-passivation of Li-metal anode to enable long stable cycling of practical Li-metal batteries, Energy Storage Materials 60, 102827 (2023)   

• Structural and Chemical Evolutions of Li/Electrolyte Interfaces in Li-metal Batteries: Tracing Compositional Changes of Electrolytes under Practical Conditions, Advanced Science 10(2), 2204812 (2023)

• Robust Cycling of Ultrathin Li-metal Enabled by Nitrate-Preplanted Li Powder Composite, Advanced Energy Materials 11(18), 2003769 (2021) "Featured in Back Cover Image"  

Intelligent nano-colloid electrolytes

Beyond classical liquid electrolytes — Tailoring the Li+ microenvironment is crucial for achieving fast ionic transfer and a mechanically reinforced solid–electrolyte interphase (SEI), which administers the stable cycling of secondary batteries. Apart from traditional salt/solvent compositional tuning, we have provided some approaches for the simultaneous modulation of Li+ transport and SEI chemistry using functional nanomaterials dispersed in the liquid electrolytes. 

Homogeneous and fast Li+ transport towards the Li surface is required for uniform and dendrite-free deposition. Moving apart from a classic ionic transport of static liquid electrolytes involving electromigration and molecular diffusion can trigger a greater disparity in the Li concentration over the Li surface. To overcome this inherent problem, we invented a convective Li+ transfer for suppressing dendrite growth through magnetic nanospinbar (NSB)-dispersed colloidal electrolytes.

Related publications 📝

• Intelligent Nano-Colloidal Electrolytes for Stabilizing Lithium Metal Anodes: A Review, ChemElectroChem (2024)

• Modulating Ionic Transport and Interface Chemistry via Surface-Modified Silica Carrier in Nano Colloid Electrolyte for Stable Cycling of Li-Metal Batteries, Small Online published (2023)  "Featured in Inside Back Cover"   

• Dynamic Ionic Transport Actuated by Nanospinbar-dispersed Colloidal Electrolytes Toward Dendrite-free Electrodeposition, Advanced Functional Materials 32(40), 2204052 (2022)  "Selected as Journal Front Cover" 

• Lithium Dendrite Suppression with Silica Nanoparticle-Dispersed Colloidal Electrolyte, ACS Applied Materials & Interfaces 12 (33), 37188–37196  (2020)

Seamless charging Li-ion in extreme conditions

Pushing the limits of charging rates — Cell engineering has been advanced to higher specific energy density by many battery researchers in the academy and industry for the long driving mileage of battery-powered EVs. In particular, building up the thick and dense electrode on the unit area of the Cu current collector is a successful method for gaining a lightweight capacity battery. Nevertheless, this current cell design is a bottleneck to fast charging due to cell polarization from limited Li diffusion by volume change, and it easily breaks and newly forms the SEI layer; depletion of Li+ source leads to radical capacity fading. To overcome cell polarization for the popularization of fast chargeable EVs, designing innovative materials and interface chemistry is crucial in the battery industry.

Related publications 📝

• Low viscous, highly ionic conductive ester-based high concentration electrolytes for ultrafast charging Li-ion batteries, To be submitted (2024)

• Diluent-mediated interfacial reactions in localized-high-concentration electrolytes for fast-charging lithium-ion batteries, Submitted (2024)

• Sequential Effect of Dual-layered Hybrid Graphite Anodes on Electrode Utilization during Fast-charging Li-ion Batteries, Advanced Science (2024)

• Boosting Interfacial Kinetics in Extremely Fast Charging Li-ion Batteries with Linear Carbonate-based, LiPF6-concentrated Electrolytes, Energy Storage Materials Online published (2023). 

Imaging-driven battery diagnosis

Looking inside the battery — Building a safer battery has become a common goal of academia and industry. Although the small errors inside the cells trigger catastrophic failures, identifying local defects or damages without anatomizing the cells and diagnosing cell safety and degradation remain challenging. EMDL group has expertise in real-time, non-invasive magnetic field imaging (MFI) that signals the battery current-induced magnetic field to visualize the current flow of the Li-ion pouch cells. A high-speed, spatially resolved MFI scan successfully derives the current distribution pattern from the cells with different tab positioning at a current load. 

Related publications 📝

• Diagnosis of Current Flow Patterns Inside Fault-Simulated Li-Ion Batteries via Non-Invasive, In Operando Magnetic Field Imaging, Small Methods Online published (2023) Selected as "Editor's Choice" and "Hot Topic: Magnetic Materials" 

• Multi-scale Imaging Techniques for Real-time, Non-invasive Diagnosis of Li-ion Battery Failures, Small Science Online published (2023).   

Building safe, sustainable batteries

Safe, environmentally benign, cost-positive battery things — Instead of a Li-ion battery that uses an organic solvent with high fire risk as an electrolyte, we conducted to ensure stability in a grid-scale battery system, such as ESS, by using an aqueous Zn-ion battery with water as an electrolyte. The huge challenges are hydrogen evolution reaction (HER) and notorious Zn dendrite growth. The water decomposition at the operating voltage of the battery generates hydrogen, resulting in by-products and decreasing utilization efficiency of Zn. Dendrites growing on zinc metal surfaces cause internal short circuits, reducing battery life.

Related publications 📝

• Current-mediated suppression of hydrogen evolution reaction in determination of Zn-metal Coulombic efficiency, Submitted (2024)

• Optimal cell configuration for accessing Zn reversibility in flowless Zn-Br batteries" Submitted (2024)

• In-situ bi-layer coating of Zn protection layer guided by metal fluoride additives for sustained cycling of aqueous Zn metal batteries, Chemical Engineering Journal (2024)

• A hydrophilic Janus-faced separator with functionalized nanocarbon for stable cycling of aqueous Zn-metal batteries, Journal of Materials Chemistry A (2024)

• Highly Reversible Cycling of Zn-MnO2 Batteries Integrated with Acid-treated Carbon Supportive Layer, Small Methods 6(2), 2101060 (2022)