Thermally Stable PVDF-HFP-Based Gel Polymer Electrolytes for High-Performance Lithium-Ion Batteries.

The development of gel polymer electrolytes (GPEs) for lithium-ion batteries (LIBs) has paved the way to powering futuristic technological applications such as hybrid electric vehicles and portable electronic devices. Despite their multiple advantages, non-aqueous liquid electrolytes (LEs) possess certain drawbacks, such as plasticizers with flammable ethers and esters, electrochemical instability, and fluctuations in the active voltage scale, which limit the safety and working span of the batteries. However, these shortcomings can be rectified using GPEs, which result in the enhancement of functional properties such as thermal, chemical, and mechanical stability; electrolyte uptake; and ionic conductivity. Thus, we report on PVDF-HFP/PMMA/PVAc-based GPEs comprising poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and poly(methyl methacrylate) (PMMA) host polymers and poly(vinyl acetate) (PVAc) as a guest polymer. A physicochemical characterization of the polymer membrane with GPE was conducted, and the electrochemical performance of the NCM811/Li half-cell with GPE was evaluated. The GPE exhibited an ionic conductivity of 4.24 × 10-4 S cm-1, and the NCM811/Li half-cell with GPE delivered an initial specific discharge capacity of 204 mAh g-1 at a current rate of 0.1 C. The cells exhibited excellent cyclic performance with 88% capacity retention after 50 cycles. Thus, this study presents a promising strategy for maintaining capacity retention, safety, and stable cyclic performance in rechargeable LIBs.

Silkworm Protein-Derived Nitrogen-Doped Carbon-Coated Li[Ni0.8Co0.15Al0.05]O2 for Lithium-Ion Batteries.

Li[Ni0.8Co0.15Al0.05]O2 (NCA) is a cathode material for lithium-ion batteries and has high power density and capacity. However, this material has disadvantages such as structural instability and short lifespan. To address these issues, herein, we explore the impact of N-doped carbon wrapping on NCA. Sericin, an easily obtained carbon- and nitrogen-rich component of silk cocoons, is utilized as the precursor material. The electrochemical performance evaluation of N-doped carbon-coated NCA shows that the capacity retention of 0.3 NC@NCA at 1C current density is 69.83% after 200 cycles, which is about 19% higher than the 50.65% capacity retention of bare NCA. The results reveal that the sericin-resultant N-doped carbon surface wrapping improves the cycling stability of NC@NCA.

Enhanced NaFe0.5Mn0.5O2/C Nanocomposite as a Cathode for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have emerged as an alternative candidate in the field of energy storage applications. To achieve the commercial success of SIBs, the designing of active materials is highly important. O3-type layered-NaFe0.5Mn0.5O2 (NFM) materials provide higher specific capacity along with Earth-abundance and low cost. Nevertheless, the material possesses some disadvantages, such as a low rate capability and severe capacity fading during cycling. To overcome such drawbacks, composite O3-type layered NFM with carbon has been prepared for the cathode electrode of SIBs through a facile solution combustion method followed by calcination process. The introduction of carbon sources into NFM material provides excellent electrochemical performances; moreover, the practical limitations of NFM material such as low electrical conductivity, structural degradation, and cycle life are effectively controlled by introducing carbon sources into the host material. The NFM/C-2 material delivers the specific charge capacities of 171, 178, and 166 mA h g-1; and specific discharge capacities of 188, 169, and 162 mA h g-1, in the first 3 cycles, respectively.

Thermally assisted conversion of biowaste into environment-friendly energy storage materials for lithium-ion batteries.

This study reports the thermally assisted solid-state synthesis of a cathode comprising a biowaste-derived nitrogen-doped carbon coating on LiFePO4 (LFP) for Li-ion batteries. The eggshell membrane (ESM), which mainly consists of collagen, is converted into nitrogen-doped carbon with good ionic and electrical conductivity during thermally driven decomposition. The ESM-coated LFP (ESM@LFP) containing pyrrolic nitrogen, pyridinic nitrogen, and oxidized pyridinic nitrogen has been motivated to improve its ionic and electrical conductivity, that promotes the movement of Li-ions and electrons on the LFP surface. ESM@LFP exhibits stable cyclability and ~16.3% of increased specific discharge capacity for 100 cycles at a current rate of 1C compared to bare LFP.