Thermal and Adhesion Properties of Fluorosilicone Adhesives Following Incorporation of Magnesium Oxide and Boron Nitride of Different Sizes and Shapes

Thermally conductive adhesives were prepared by incorporating magnesium oxide (MgO) and boron nitride (BN) into fluorosilicone resins. The effects of filler type, size, and shape on thermal conductivity and adhesion properties were analyzed. Higher thermal conductivity was achieved when larger fillers were used, but smaller ones were advantageous in terms of adhesion strength. Bimodal adhesives containing spherical MgOs with an average particle size of 120 μm and 90 μm exhibited the highest conductivity value of up to 1.82 W/mK. Filler shape was also important to improve the thermal conductivity as the filler type increased. Trimodal adhesives revealed high adhesion strength compared to unimodal and bimodal adhesives, which remained high after aging at 85 °C and 85% relative humidity for 168 h. It was found that the thermal and adhesion properties of fluorosilicone composites were strongly affected by the packing efficiency and interfacial resistance of the particles.

LLCZN/PEO/LiPF6 Composite Solid-State Electrolyte for Safe Energy Storage Application

All-solid-state batteries (ASSBs) are gaining traction in the arena of energy storage due to their promising results in producing high energy density and long cycle life coupled with their capability of being safe. The key challenges facing ASSBs are low conductivity and slow charge transfer kinetics at the interface between the electrode and the solid electrolyte. Garnet solid-state electrolyte has shown promising results in improving the ion conductivity but still suffers from poor capacity retention and rate performance due to the interfacial resistance between the electrodes. To improve the interfacial resistance, we prepared a composite consisting of Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) garnet material as the ceramic, polyethylene oxide (PEO) as the polymer, and lithium hexafluorophosphate (LiPF6) as the salt. These compounds are mixed in a stoichiometric ratio and developed into a very thin disc-shaped solid electrolyte. The LLCZN provides a lithium-ion transport path to enhance the lithium-ion conduction during charging and discharging cycles, while the LiPF6 contributes more lithium ions via the transport path. The PEO matrix in the composite material aids in bonding the compounds together and creating a large contact area, thereby reducing the issue of large interfacial resistance. FESEM images show the porous nature of the electrolyte which promotes the movement of lithium ions through the electrolyte. The fabricated LLCZN/PEO/LiPF6 solid-state electrolyte shows outstanding electrochemical stability that remains at 130 mAh g−1 up to 150 charging and discharging cycles at 0.05 mA cm−2 current. All the specific capacities were calculated based on the mass of the cathode material (LiCoO2). In addition, the coin cell retains 85% discharge capacity up to 150 cycles with a Coulombic efficiency of approximately 98% and energy efficiency of 90% during the entire cycling process.

Lithium-Ion-Conducting Ceramics-Coated Separator for Stable Operation of Lithium Metal-Based Rechargeable Batteries

Lithium metal anode is regarded as the ultimate negative electrode material due to its high theoretical capacity and low electrochemical potential. However, the significantly high reactivity of Li metal limits the practical application of Li metal batteries. To improve the stability of the interface between Li metal and an electrolyte, a facile and scalable blade coating method was used to cover the commercial polyethylene membrane separator with an inorganic/organic composite solid electrolyte layer containing lithium-ion-conducting ceramic fillers. The coated separator suppressed the interfacial resistance between the Li metal and the electrolyte and consequently prolonged the cycling stability of deposition/dissolution processes in Li/Li symmetric cells. Furthermore, the effect of the coating layer on the discharge/charge cycling performance of lithium-oxygen batteries was investigated.

Tuning Na3Hf2Si2PO12 electrolyte surfaces by metal coating for high-rate and long cycle life all-solid sodium-ion batteries

Solid-state sodium ion batteries have attracted widely attentions due to its high energy density, low cost and high security. However, the poor contact and high interfacial resistance between sodium and...

Improving the alkali metal electrode/inorganic solid electrolyte contact via room-temperature ultrasound solid welding

The combination of alkali metal electrodes and solid-state electrolytes is considered a promising strategy to develop high-energy rechargeable batteries. However, the practical applications of these two components are hindered by the large interfacial resistance and growth of detrimental alkali metal depositions (e.g., dendrites) during cycling originated by the unsatisfactory electrode/solid electrolyte contact. To tackle these issues, we propose a room temperature ultrasound solid welding strategy to improve the contact between Na metal and Na3Zr2Si2PO12 (NZSP) inorganic solid electrolyte. Symmetrical Na|NZSP | Na cells assembled via ultrasonic welding show stable Na plating/stripping behavior at a current density of 0.2 mA cm−2 and a higher critical current density (i.e., 0.6 mA cm−2) and lower interfacial impedance than the symmetric cells assembled without the ultrasonic welding strategy. The beneficial effect of the ultrasound welding is also demonstrated in Na|NZSP | Na3V2(PO4)3 full coin cell configuration where 900 cycles at 0.1 mA cm−2 with a capacity retention of almost 90% can be achieved at room temperature.