A phthalocyanine-grafted MA-VA framework polymer as a high performance anode material for lithium/sodium-ion batteries.

A porous MA-VA-PcNi polymer was prepared by grafting nickel phthalocyanine (PcNi) onto the main chain of a maleic anhydride-vinyl acetate (MA-VA) polymer, and an MA-VA-PcNi electrode is prepared by electrospinning technology to inhibit the agglomeration of the active powder effectively, which produces spherical particles with a diameter of 100-300 nm. The synthesized MA-VA-PcNi polymer is used as the anode for lithium-ion and sodium-ion batteries, exhibiting excellent energy storage behaviors. The MA-VA-PcNi/Li battery displays a high capacity of 610 mA h g-1 and can still remain at 507 mA h g-1 with a retention rate of 83.1% after 400 cycles at a current density of 200 mA g-1. Even at a high current density of 2 A g-1, the specific capacity can remain at 195 mA h g-1. In addition, the MA-VA-PcNi/Na battery displays a high capacity of 336 mA h g-1 and can still remain at 278 mA h g-1 with a retention rate of 82.7% after 400 cycles at a current density of 100 mA g-1. A high specific capacity of 164 mA h g-1 can also be achieved at a high current density of 1 A g-1. After nickel phthalocyanine (PcNi) was grafted onto the MA-VA polymer, aggregation between phthalocyanine rings was effectively prevented, and this exposes more active sites. At the same time, the spherical particles obtained by electrospinning technology further improve the dispersion and increase the number of active sites of the active materials. Finally, the electrode materials show excellent energy storage behavior for lithium-ion and sodium-ion batteries, which provides a new idea for designing high-performance energy storage materials for organic electrodes.

Tetraethylthiophene-2,5-diylbismethylphosphonate: A Novel Electrolyte Additive for High-Voltage Batteries.

In this work, a novel high-voltage electrolyte additive, tetraethylthiophene-2,5-diylbismethylphosphonate (TTD), was synthesized, and the influence of TTD on the electrolyte and its electrochemical performance under different voltages were studied by changing the content of the TTD additive. The results showed that the TTD additive significantly improved the capacity, cycle stability, and rate capability of batteries when charging/discharging at high voltages. After adding 1 % TTD to the basic electrolyte, the capacity retention rate of batteries after 200 cycles at 4.2, 4.3, 4.4, and 4.5 V increased by 20.8, 18.3, 50, and 31.9 %, respectively. In addition, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results showed that TTD could effectively inhibit the decomposition of the electrolyte and participate in the formation of a uniform, thin, and stable cathode electrolyte interphase (CEI) film on the electrode surface, thereby effectively inhibiting the side reaction between the electrolyte decomposition product and the CEI membrane, and finally improving the high-voltage performance of the battery. The TTD additive may provide a cost-effective solution for high-performance high-voltage electrolytes.

1,4,5,8-Naphthalenetetracarboxylic dianhydride grafted phthalocyanine macromolecules as an anode material for lithium ion batteries.

For solving the problems of high solubility in electrolytes, poor conductivity and low active site utilization of organic electrode materials, in this work, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) grafted nickel phthalocyanine (TNTCDA-NiPc) was synthesized and used as an anode material for lithium ion batteries. As a result, the dispersibility, conductivity and dissolution stability are improved, which is conducive to enhancing the performance of batteries. The initial discharge capacity of the TNTCDA-NiPc electrode is 859.8 mA h g-1 at 2 A g-1 current density, which is much higher than that of the NTCDA electrode (247.4 mA h g-1). After 379 cycles, the discharge capacity of the TNTCDA-NiPc electrode is 1162.9 mA h g-1, and the capacity retention rate is 135.3%, which is 7 times that of the NTCDA electrode. After NTCDA is grafted to the phthalocyanine macrocyclic system, the dissolution of the NTCDA in the electrolyte is reduced, and the conductivity and dispersion of the NTCDA and phthalocyanine ring are also improved, so that more active sites of super lithium intercalation from NTCDA and phthalocyanine rings are exposed, which results in better electrochemical performance. The strategy of grafting small molecular active compounds into macrocyclic conjugated systems used in this work can provide new ideas for the development of high performance organic electrode materials.

Porous diatomite-mixed 1,4,5,8-NTCDA nanowires as high-performance electrode materials for lithium-ion batteries.

A porous composite electrode composed of diatomite-mixed 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) is prepared by electrostatic spinning technology. Compared with traditional coated electrodes without diatomite mixing, the obtained composite electrode materials have higher porosity, larger specific surface area and faster lithium ion transport channels, which makes them exhibit better electrochemical performance, such as smaller impedance, higher capacity, and better cycling stability and rate performance. The electrospun diatomite-mixed 1,4,5,8-NTCDA composite (ED-1,4,5,8-NTCDA) electrode shows an initial coulombic efficiency of 77.2%, which is much higher than that of the electrospun 1,4,5,8-NTCA (E-1,4,5,8-NTCDA) electrode without diatomite mixing (63.8%) and the coated 1,4,5,8-NTCA (C-1,4,5,8-NTCDA) electrode (48.3%). Moreover, the ED-1,4,5,8-NTCDA electrode displays an initial discharge capacity of 1106.5 mA h g-1, which is much higher than that of the E-1,4,5,8-NTCDA electrode (546.0 mA h g-1) and the C-1,4,5,8-NTCDA electrode (185.4 mA h g-1). After 200 cycles, the capacity of the ED-1,4,5,8-NTCDA electrode remains at 1008.5 mA h g-1 with a retention ratio of 91.2%, which is also much higher than that of 753.2 mA h g-1 for the E-1,4,5,8-NTCDA electrode and 288.1 mA h g-1 for the C-1,4,5,8-NTCDA electrode. Even at a higher current density of 1500 mA g-1, its capacity remains above 508.9 mA h g-1. The ED-1,4,5,8-NTCDA electrode presents superior performance, which opens up a promising new approach for further utilization of organic materials as electrode materials in rechargeable lithium-ion batteries.