Xiaoyu Jiang

A Highly Thermostable Ceramic-Grafted Microporous Polyethylene Separator for Safer Lithium-Ion Batteries.

The safety concern is a critical obstacle to large-scale energy storage applications of lithium-ion batteries. A thermostable separator is one of the most effective means to construct the safe lithium-ion batteries. Herein, we demonstrate a novel ceramic (SiO2)-grafted PE separator prepared by electron beam irradiation. The separator shows similar thickness and pore structure to the bare separator, while displaying strong dimensional thermostability, as the shrinkage ratio is only 20% even at an elevated temperature of 180 °C. Besides, the separator is highly electrochemically inert, showing no adverse effect on the energy and power output of the batteries. Considering the excellent electrochemical and thermal stability, the SiO2-grafted PE separator developed in this work is greatly beneficial for constructing safer lithium-ion batteries.

A Safer Sodium-Ion Battery Based on Nonflammable Organic Phosphate Electrolyte.

Sodium‐ion batteries are now considered as a low‐cost alternative to lithium‐ion technologies for large‐scale energy storage applications; however, their safety is still a matter of great concern for practical applications. In this paper, a safer sodium‐ion battery is proposed by introducing a nonflammable phosphate electrolyte (trimethyl phosphate, TMP) coupled with NaNi0.35Mn0.35Fe0.3O2 cathode and Sb‐based alloy anode. The physical and electrochemical compatibilities of the TMP electrolyte are investigated by igniting, ionic conductivity, cyclic voltammetry, and charge–discharge measurements. The results exhibit that the TMP electrolyte with FEC additive is completely nonflammable and has wide electrochemical window (0–4.5 V vs. Na/Na+), in which both the Sb‐based anode and NaNi0.35Mn0.35Fe0.3O2 cathode show high reversible capacity and cycling stability, similarly as in carbonate electrolyte. Based on these results, a nonflammable sodium‐ion battery is constructed by use of Sb anode, NaNi0.35Mn0.35Fe0.3O2 cathode, and TMP + 10 vol% FEC electrolyte, which works very well with considerable capacity and cyclability, demonstrating a promising prospect to build safer sodium‐ion batteries for large‐scale energy storage applications.

Novel Ceramic-Grafted Separator with Highly Thermal Stability for Safe Lithium-Ion Batteries

The separator is a critical component of lithium-ion batteries (LIBs), which not only allows ionic transport while it prevents electrical contact between electrodes but also plays a key role for thermal safety performance of LIBs. However, commercial separators for LIBs are typically microporous polyolefin membranes that pose challenges for battery safety, due to shrinking and melting at elevated temperature. Here, we demonstrate a strategy to improve the thermal stability and electrolyte affinity of polyethylene (PE) separators. By simply grafting the vinylsilane coupling reagent on the surface of the PE separator by electron beam irradiation method and subsequent hydrolysis reaction into the Al3+ solution, an ultrathin Al2O3 layer is grafted on the surface of the porous polymer microframework without sacrificing the porous structure and increasing the thickness. The as-synthesized Al2O3 ceramic-grafted separator (Al2O3-CGS) shows almost no shrinkage at 150 °C and decreases the contact angle of the conventional electrolyte compared with the bare PE separator. Notably, the full cells with the Al2O3-CGSs exhibit better cycling performance and rate capability and also provide stable open circuit voltage even at 170 °C, indicating its promising application in LIBs with high safety and energy density.

A novel bifunctional thermo-sensitive poly(lactic acid)@poly(butylene succinate) core–shell fibrous separator prepared by a coaxial electrospinning route for safe lithium-ion batteries

Safety, energy and power density are critical issues for successful application of lithium-ion batteries (LIBs) in portable electronic devices, electric vehicles (EVs) and large-scale energy storage systems. A separator is a key component to ensure the safety and improve the performance of LIBs. Herein, a thermally induced shutdown separator of poly(lactic acid)@poly(butylene succinate) (PLA@PBS) is successfully fabricated by a facile coaxial electrospinning process. The electrospun PLA@PBS separator possesses synchronous characteristics of high thermal sensitivity (prompt shutdown response) and high thermal stability (structural integrity) as well as excellent wettability to liquid electrolytes. Full cells using the bifunctional PLA@PBS separators exhibit superior cycling performance and rate capability compared to those using commercial Celgard separators. These attractive characteristics make the PLA@PBS membrane a promising separator for high safety and high energy/power density LIBs.

An All-Phosphate and Zero-Strain Sodium-Ion Battery Based on Na3V2(PO4)3 Cathode, NaTi2(PO4)3 Anode, and Trimethyl Phosphate Electrolyte with Intrinsic Safety and Long Lifespan

Development of intrinsically safe and long lifespan sodium-ion batteries (SIBs) is urgently needed for large-scale energy storage applications. However, most of the currently developed SIBs suffer from insufficient cycle life and potential unsafety. Herein, we construct an all-phosphate sodium-ion battery (AP-SIB) using a Na3V2(PO4)3 cathode, NaTi2(PO4)3 anode, and nonflammable trimethyl phosphate (TMP) electrolyte. The AP-SIB exhibits not only high safety, high rate performance, and ultralong cycle life but also zero-strain characteristics due to the inverse volume change of the phosphate cathode and anode during charge and discharge cycles, offering a safer and cycle-stable Na-ion technology for electric storage applications.

Novel 2D Layered Molybdenum Ditelluride Encapsulated in Few-Layer Graphene as High-Performance Anode for Lithium-Ion Batteries

Molybdenum ditelluride nanosheets encapsulated in few-layer graphene (MoTe2 /FLG) are synthesized by a simple heating method using Te and Mo powder and subsequent ball milling with graphite. The as-prepared MoTe2 /FLG nanocomposites as anode materials for lithium-ion batteries exhibit excellent electrochemical performance with a highly reversible capacity of 596.5 mAh g-1 at 100 mA g-1 , a high rate capability (334.5 mAh g-1 at 2 A g-1 ), and superior cycling stability (capacity retention of 99.5% over 400 cycles at 0.5 A g-1 ). Ex situ X-ray diffraction and transmission electron microscopy are used to explore the lithium storage mechanism of MoTe2 . Moreover, the electrochemical performance of a MoTe2 /FLG//0.35Li2 MnO3 ·0.65LiMn0.5 Ni0.5 O2 full cell is investigated, which displays a reversible capacity of 499 mAh g-1 (based on the MoTe2 /FLG mass) at 100 mA g-1 and a capacity retention of 78% over 50 cycles, suggesting the promising application of MoTe2 /FLG for lithium-ion storage. First-principles calculations exhibit that the lowest diffusion barrier (0.18 eV) for lithium ions along pathway III in the MoTe2 layered structure is beneficial for improving the Li intercalation/deintercalation property.

High Capacity and Cycle-Stable Hard Carbon Anode for Nonflammable Sodium-Ion Batteries

Nonflammable phosphate electrolytes are in principle able to build intrinsically safe Na-ion batteries, but their electrochemical incompatibility with anodic materials, especially hard carbon anode, restricts their battery applications. Here, we propose a new strategy to enable high-capacity utilization and cycle stability of hard carbon anodes in the nonflammable phosphate electrolyte by using low-cost Na+ salt with a high molar ratio of salt/solvent combined with an solid electrolyte interphase film-forming additive. As a result, the carbon anode in the trimethyl phosphate (TMP) electrolyte with a high molar ratio of [NaClO4]/[TMP] and 5% fluoroethylene carbonate additive demonstrates a high reversible capacity of 238 mAh g-1, considerable rate capability, and long-term cycling life with 84% capacity retention over 1500 cycles. More significantly, this work provides a promising route to build intrinsically safe and low-cost sodium-ion batteries for large-scale energy storage applications.