RESUMEN
A majority of flexible and wearable electronics require high operational voltage that is conventionally achieved by serial connection of battery unit cells using external wires. However, this inevitably decreases the energy density of the battery module and may cause additional safety hazards. Herein, a bipolar textile composite electrode (BTCE) that enables internal tandem-stacking configuration to yield high-voltage (6 to 12 V class) solid-state lithium metal batteries (SSLMBs) is reported. BTCE is comprised of a nickel-coated poly(ethylene terephthalate) fabric (NiPET) core layer, a cathode coated on one side of the NiPET, and a Li metal anode coated on the other side of the NiPET. Stacking BTCEs with solid-state electrolytes alternatively leads to the extension of output voltage and decreased usage of inert package materials, which in turn significantly boosts the energy density of the battery. More importantly, the BTCE-based SSLMB possesses remarkable capacity retention per cycle of over 99.98% over cycling. The composite structure of BTCE also enables outstanding flexibility; the battery keeps stable charge/discharge characteristics over thousands of bending and folding. BTCE shows great promise for future safe, high-energy-density, and flexible SSLMBs for a wide range of flexible and wearable electronics.
RESUMEN
High-voltage Li metal battery (HV-LMB) is one of the most promising energy storage technologies to achieve ultrahigh energy density. Nevertheless, electrolytes reported to date are difficult to simultaneously stabilize the Li metal anode and high-voltage cathode, especially without the assistance of expensive and corrosive high-concentration Li salts. Herein, a dual-interphase-stabilizing (DIS) and safe electrolyte that bypasses the high-concentration Li salt is reported. The electrolyte consists of high-flash-point sulfolane as solvent, molecular-orbital-engineered additives that enable stable B-F rich cathodic interphase, and unique C-F rich organic anodic interphase. The stable cycling of both Li metal anode and 4.75 V-LiCoO2 cathode in the DIS electrolyte (> 500 cycles) is demonstrated. HV-LMB pouch cells of a high energy density (435 Wh kg-1) can sustainably operate for more than 100 cycles. Moreover, the low cost and high thermal stability of the DIS electrolyte offer superior cost-effectiveness and safety for large-scale applications of HV-LMBs in the future.
RESUMEN
Lightweight and high-performance conductive polymer composites (CPCs) have attracted much attention for electromagnetic interference (EMI) shielding. Herein, the porous structure was constructed in poly(oxymethylene)/multi-wall carbon nanotube (POM/MWCNT) nanocomposites via assisting by poly(l-lactide) (PLLA). First, the POM/PLLA/MWCNT (S-PMLNT) nanocomposites were obtained by melt mixing and compression molding. Second, the nanoporous POM/MWCNT (P-PMNT) nanocomposites were fabricated by selectively dissolving PLLA, solvent exchanging and freeze-drying. Because of well miscible between PLLA and POM, the homogeneous nanopores could be successfully fabricated in the P-PMNT composites by removing the PLLA phase. The multiple reflections and scattering of microwaves happened on the walls of these nanopores, which endowed the P-PMNT nanocomposites having higher EMI shielding effectiveness (SE) in comparison of the S-PMLNT nanocomposites, although the P-PMNT nanocomposites exhibited the lower electrical conductivity. For example, the S-PMLNT samples with 10 wt% MWCNTs showed an EMI SE of 48.1 dB and an electrical conductivity of 333 S/m, which changed to 58.6 dB in EMI SE and 125 S/m in electrical conductivity after removing PLLA phase. Furthermore, the P-PMNT10 nanocomposites had outstanding the EMI normal SE (SE/d) of 29.3 dB mm-1 and the EMI specific shielding effectiveness (SSE/d) of 344.4 dB cm2 g-1 because of their low density. In addition, the P-PMNT nanocomposites maintained high compression and tensile strength simultaneously.