Cross-Linked PVA/HNT Composite Separator Enables Stable Lithium-Organic Batteries under Elevated Temperature

Halloysite nanotubes enhanced polyimide/oxidized-lignin nanofiber separators for long-cycling lithium metal batteries

The high energy density and robust cycle properties of lithium-ion batteries contribute to their extensive range of applications. Polyolefin separators are often used for the purpose of storing electrolytes, hence ensuring the efficient internal ion transport. Nevertheless, the electrochemical performance of lithium-ion batteries is constrained by its limited interaction with electrolytes and poor capacity for cation transport. This work presents the preparation of a new bio-based nanofiber separator by combining oxidized lignin (OL) and halloysite nanotubes (HNTs) with polyimide (PI) using an electrospinning technique. Analysis was conducted to examine and compare the structure, morphology, thermal characteristics, and EIS of the separator with those of commercially available polypropylene separator (PP). The results indicate that the PI@OL and PI-OL@ 10 % HNTs separators exhibit higher lithium ion transference number and ionic conductivity. Moreover, the use of HNTs successfully impeded the proliferation of lithium dendrites, hence exerting a beneficial impact on both the cycle performance and multiplier performance of the battery. Consequently, after undergoing 300 iterations, the battery capacity of LiFePO4|PI-OL@ 10 % HNTs|Li stays at 92.1 %, surpassing that of PP (86.8 %) and PI@OL (89.6 %). These findings indicate that this new bio-based battery separator (PI-OL@HNTs) has the great potential to serve as a substitute for the commonly used PP separator in lithium metal batteries.

A Long-Life and Excellent Rate-Capability Aqueous Zn-Benzoquinone Battery Enabled by Iodine-Catalyzed Cathode

Benzoquinone (BQ) is considered to be a desirable cathode material for aqueous zinc-based batteries. The major limitations of BQ electrode are the severe sublimation and poor electrical conductivity, which results in serious mass loss during electrode preparation and inferior rate performance. In this study, iodine (I2) species are utilized as an efficient catalyst for the highly reversible conversion of BQ/BQ2- couple in the Zn-BQ battery system, wherein N-doped porous carbon is employed as a host material for anchoring the BQ molecule. In the combination electrode (denoted as BQ-I@NPC) with 1wt% I2 additive where I2 can serve as a carrier to accelerates the Zn2+ transmission, and reduce the voltage hysteresis of the electrode. As a result, the BQ-I@NPC cathode delivers a high specific capacity of ≈482 mAh g-1 at 0.25 A g-1, realizing a high energy density of 545 Wh kg-1 (based on BQ), which is the highest values among reported organic cathode materials for aqueous Zn-based batteries. Also, a high BQ loading (8 mg cm-2) can be attained, and achieving a superior cycling stability with a capacity retention of ≈80% after 20,000 times at 10 C. The work proposes an effective approach toward high performance organic electrode materials.

An electrospun three-layer nanofibrous membrane-based in situ gel separator for efficient lithium-organic batteries

An in situ gel separator based on an electrospun three-layer nanofibrous membrane (PSE11-Gel) is developed for high-performance lithium-organic batteries (LOBs). The highly efficient shuttle effect inhibition of organic cathode molecules or lithiated intermediates has been demonstrated for PSE11-Gel to realize high-capacity stable LOBs.

Spiro-Twisted Benzoxazine Derivatives Bearing Nitrile Group for All-Solid-State Polymer Electrolytes in Lithium Batteries

In this study, two nitrile-functionalized spiro-twisted benzoxazine monomers, namely 2,2′-((6,6,6′,6′-tetramethyl-6,6′,7,7′-tetrahydro-2H,2′H-8,8′-spirobi[indeno[5,6-e][1,3]oxazin]-3,3′(4H,4′H)-diyl)bis(4,1-phenylene))diacetonitrile (TSBZBC) and 4,4′-(6,6,6′,6′-tetramethyl-6,6′,7,7′-tetrahydro-2H,2′H-8,8′-spirobi[indeno[5,6-e][1,3]oxazin]-3,3′(4H,4′H)-diyl)dibenzonitrile (TSBZBN) were successfully developed as cross-linkable precursors. In addition, the incorporation of the nitrile group by covalent bonding onto the crosslinked spiro-twisted molecular chains improve the miscibility of SPE membranes with lithium salts while maintaining good mechanical properties. Owing to the presence of a high fractional free volume of spiro-twisted matrix, the –CN groups would have more space for rotation and vibration to assist lithium migration, especially for the benzyl cyanide-containing SPE. When combined with poly (ethylene oxide) (PEO) electrolytes, a new type of CN-containing semi-interpenetrating polymer networks for solid polymer electrolytes (SPEs) were prepared. The PEO-TSBZBC and PEO-TSBZBN composite SPEs (with 20 wt% crosslinked structure in the polymer) are denoted as the BC20 and BN20, respectively. The BC20 sample exhibited an ionic conductivity (σ) of 3.23 × 10⁻⁴ S cm⁻¹ at 80 °C and a Li⁺ ion transference number of 0.187. The LiFePO₄ (LFP)|BC20|Li sample exhibited a satisfactory charge–discharge capacity of 163.6 mAh g⁻¹ at 0.1 C (with approximately 100% coulombic efficiency). Furthermore, the Li|BC20|Li cell was more stable during the Li plating/stripping process than the Li|BN20|Li and Li|PEO|Li samples. The Li|BC20|Li symmetric cell could be cycled continuously for more than 2700 h without short-circuiting. In addition, the specific capacity of the LFP|BC20|Li cell retained 87% of the original value after 50 cycles.