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 provides a more facile and feasible approach than physical coatings, and is the key to tailoring both cathode and anode interfaces. Additives, ionic liquid, eutectic, dual-salt hybrid, single-ion conductor, etc are being researched in our group. Our interests and aim are to realize dual functions of the electrolytes for improving both cathode and anode for, in particular, Zn-iodine batteries.

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. "Membranne-free" is an interesting route towards high-energy-density and/or high-total-capacity prototypes.

While we are loyal to manganese oxides and nickel oxide cathodes, we are also fan of conversion type cathode materials which is mainly iodine (or ZnI2). The community is extending to other types of aqueous batteries (such as Sulfur, Tin, Bromide, Selenium). 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 hybrid 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) or typical research articles (NVP cathode, MoSSe nanosheet anode).

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

Nanoporous carbons are useful for supercapacitors, metal-ion capacitors, and metal-ion batteries. Pore engineering are important to realize ion confinement inside nanopores and high plateau-capacity (524 mAh/g) for Na storage (Collaborate with Huanwen Wang, Liqiang Mai/Liang Zhou).

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, high-entropy alloys and oxides, 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 - A lot of fun.