Research Group of Hong Jin FAN

I. Aqueous Metal Batteries

We started our research on aqueous Zn-ion batteries since 2018 when we published the first review paper (Recent advances in Zn-ion batteries, Adv. Funct. Mater. 2018).

Our interests is to increase the durability and energy density of AZB by fighting the challenges associated with cathode, Zn anode, and electrolyte.

Zn metal is currently a popular anode for AZB. It needs to be stablized by many interesting methods such as hydrogel, zeolites, LbL organic layer, and MXene membrane. Artificial SEIs in AZB may not be as effective as spontaneous SEI but it renders interesting new sciences.

Electrolyte engineering is the key to tailoring both cathode and anode interfaces. Additives, ionic liquid, eutectic, cocktail, single-ion conductor, etc are being researched. Our interests and aim are to realize dual function for improveing both cathode and anode in one cell.

In particular, we have progressively improved the hydrogel function from pure anode protection, heterogeneous bilayer, cation-conduction dominance, to in-situ spontaneous electropolymerization. Lots of fun with hydrogel which may enable smart batteries.

Occasionally, we design unique battery devices such as decoupled Zn-S battery, Zn-Na dual-ion battery, paper batteries, self-charging Zn battery.

While we are loyal to manganese oxides and nickel oxide cathodes, we are also fan of conversion type oxides which is mainly iodine (or ZnI2) cathode. The community is extending to other types of aqueous batteries (such as Sulfur, Tin, Bromide, Selenium based). We are interested but we act very slowly - my bad.

II. Sodium-Ion Batteries

In early years, we worked a lot on Na-ion battery or capacitive batteries, focusing on developping array-type nanostructures for fast charging capabilities. Please refer to our review article (Non-Aqueous Hybrid Lithium and Sodium Ion Capacitors, Adv. Mater.) or typical examples (NVP cathode, MoSSe nanosheet anode)

We engineer the cathode interface with polymer electrolyte for Na-ion batteries.

Nanoporous carbons are useful for supercapacitors, metal-ion capacitors, and metal-ion batteries. We deploy various types of carbon-based anode materials to realize ion confinement inside nanopores, or to realize high-plateau-capacity Na storage (Collaborating with Huanwen Wang, Liqiang Mai).

III. Electrocatalysis

We develop new electrocatalysts for interesting process including HER, OER, ORR, and CO2RR. We are also fabricating devices to integrate energy conversion and storage functions.

Catalysts include single-metal or dual-metal atoms, atomic clusters, TMD layered materials, amorphous materials, etc.

We dive deep into the working mechanism and understand various beneficial effects on the intrinsic activity, including biaxial strain, electronegativity, in-situ surface adsorption, and atomic defects. Machine learning for material screening and descriptor indentification is also being attempted - quite fun.