Self-Expanding Ion-Transport Channels on Anodes for Fast-Charging Lithium-Ion Batteries.

We propose self-expanding lithium-ion transport channels to construct a fast-charging anode and realize high-performance fast-charging Li-ion batteries. The self-expanded Li-ion transport channels can be enabled by a self-reversible conversion of chemical bonds with different bond lengths in the anode driven by the interactions with Li ions during cycling, reduce the energy barrier of Li-ion transport and allow a fast Li-ion solid-state diffusion, whereby the severe voltage polarization and Li metal plating are effectively eliminated. Our proof-of-concept demonstration of the self-reversible conversion of chemical bonds on the surface of graphdiyne successfully verifies the self-expanded Li-ion transport channels, self-accelerated Li in-plane/out-of-plane migration, and superior fast-charging capability with a high capacity (342 mA h g-1 ) and an ultra-long lifespan (22 000 cycles) under extremely fast-charging conditions (6 C rate, 1 C=744 mA g-1 ), even at low temperatures (-10 °C).

A Chemistry and Microstructure Perspective on Ion-Conducting Membranes for Redox Flow Batteries.

Redox flow batteries (RFBs) are among the most promising grid-scale energy storage technologies. However, the development of RFBs with high round-trip efficiency, high rate capability, and long cycle life for practical applications is highly restricted by the lack of appropriate ion-conducting membranes. Promising RFB membranes should separate positive and negative species completely and conduct balancing ions smoothly. Specific systems must meet additional requirements, such as high chemical stability in corrosive electrolytes, good resistance to organic solvents in nonaqueous systems, and excellent mechanical strength and flexibility. These rigorous requirements put high demands on the membrane design, essentially the chemistry and microstructure associated with ion transport channels. In this Review, we summarize the design rationale of recently reported RFB membranes at the molecular level, with an emphasis on new chemistry, novel microstructures, and innovative fabrication strategies. Future challenges and potential research opportunities within this field are also discussed.

Physically and Chemically Stable Anion Exchange Membranes with Hydrogen-Bond Induced Ion Conducting Channels.

Anion exchange membranes (AEMs) with desirable properties are the crucial components for numerous energy devices such as AEM fuel cells (AEMFCs), AEM water electrolyzers (AEMWEs), etc. However, the lack of suitable AEMs severely limits the performance of devices. Here, a series of physically and chemically stable AEMs have been prepared by the reaction between the alkyl bromine terminal ether-bond-free aryl backbone and the urea group-containing crosslinker. Morphology analyses confirm that the hydrogen bonding interaction between urea groups is capable of driving the ammonium cations to aggregate and further form continuous ion-conducting channels. Therefore, the resultant AEM demonstrates remarkable OH− conductivity (59.1 mS cm−1 at 30 °C and 122.9 mS cm−1 at 90 °C) despite a moderate IEC (1.77 mmol g−1). Simultaneously, due to the adoption of ether-bond-free aryl backbone and alkylene chain-modified trimethylammonium cation, the AEM possesses excellent alkaline stability (87.3% IEC retention after soaking in 1 M NaOH for 1080 h). Moreover, the prepared AEM shows desirable mechanical properties (tensile stress > 25 MPa) and dimensional stability (SR = 20.3% at 90 °C) contributed by the covalent-bond and hydrogen-bond crosslinking network structures. Moreover, the resulting AEM reaches a peak power density of 555 mW cm−2 in an alkaline H2/O2 single fuel cell at 70 °C without back pressure. This rational structural design presented here provides inspiration for the development of high-performance AEMs, which are crucial for membrane technologies.

Dendrite-Free, High-Rate, Long-Life Lithium Metal Batteries with a 3D Cross-Linked Network Polymer Electrolyte.

A 3D network gel polymer electrolyte (3D-GPE) is designed for lithium metal batteries and prepared by an initiator-free one-pot ring-opening polymerization technique. This 3D-GPE exhibits an unprecedented combination of mechanical strength, ionic conductivity, and more importantly, effective suppression of Li dendrite growth. The produced lithium-based battery presents long life, high rate, and excellent safety.