ZnMn 2 O 4 flakes, composed of interconnected nanoparticles were synthesized by using a hydrothermal technique and treated subsequently with nitrogen-doped graphene (NG) to obtain a composite containing graphene sheets decorated with ZnMn 2 O 4 nanoparticles. When explored as a lithium-battery anode, ZnMn 2 O 4 /NG exhibits a superior electrochemical performance compared to a pristine ZnMn 2 O 4 anode. Interestingly, the ZnMn 2 O 4 /NG composite anode displays a steady-state reversible capacity of 1400 mAh g À1 at 100 mA g À1 , which is higher than the theoretical capacity and the highest ever capacity achieved so far, with respect to the ZnMn 2 O 4 electrode material. Furthermore, the nanocomposite anode shows a stable capacity of 790 mAh g À1 up to 1000 cycles and the corresponding coulombic efficiency is 99 % at 500 mA g À1 , exhibiting excellent rate capability. The superior electrochemical performance of the ZnMn 2 O 4 /NG anode may be ascribed to the multiple synergistic advantages offered by NG, such as enhanced electrode conductivity, maintenance of structural integrity upon cycling, and the effective accommodation of volume changes during charging and discharging. Our results indicate that the synthesized ZnMn 2 O 4 /NG nanocomposite anode could be considered as a promising candidate for nextgeneration high-rate lithium-ion-battery applications.

Corn silk is a waste material obtained from corn that contains carbohydrates, proteins, and vitamins. Interestingly, corn-silk-derived carbon (CSC) after activation is found to possess larger specific surface area (2550 m 2 g −1 ) and appreciable pore volume (0.95 cm 3 g −1 ). In the present investigation, CSC electrodes are used to fabricate symmetric coin and pouch cells individually and investigated for electrochemical performance in half and full cell assembly systematically. Half-cell performance of CSC exhibits a maximum specific capacity of 256 mA h g −1 at 100 mA g −1 . The subsequently assembled symmetric coin type sodium-ion capacitor (SIC) delivers a maximum specific capacitance of 126 F g −1 at 0.3 A g −1 , and the pouch cell delivers 135 F g −1 at the same current density. Symmetric capacitors are found to withstand high current densities up to ∼3 A g −1 with nominal capacitance values, thus qualifying the suitability of CSC for SIC applications. A maximum specific energy of ∼109 Wh kg −1 and a specific power of ∼12.16 kW kg −1 have been realized from the symmetric SICs. Feasibility of the fabricated devices for practical application has been demonstrated by glowing LEDs and by running a clock for 25 min.

Suitability of CPC electrode for sodium-ion batteries (SIBs) and electrical double layer capacitors (EDLCs) has been demonstrated through the present work, apart from our report on lithium-ion and lithium-sulfur batteries.

pH control synthesised ZnMn2O4 nanoparticles embedded in nitrogen doped graphene sheets demonstrate themselves to be a potential anode for sodium-ion batteries.

Interconnected microporous and heteroatom containing bio‐carbon, derived from universal household waste i. e. cooked rice has been investigated as an anode material for lithium and sodium‐ion batteries. Cooked rice derived carbon (CRC), prepared by an economically viable carbonization process, bestowed with the presence of nitrogen atom due to the bacillus cereus bacteria is chemically activated with KOH at different temperatures such as 800, 850 and 900° C. Among the prepared samples, CRC‐900 anode delivers an exceptionally high progressive capacity of ≈1000 mAh g‐1 at 100 mA g−1 for 100 cycles and reasonable capacity of 169 mAh g−1 for 1000 cycles. Further, CRC‐900 anode demonstrates high rate performance by delivering 260 mAh g−1 at 2 A g−1 in LIBs and an acceptable capacity of 78 mAh g−1 in SIBs at 2 A g−1condition. CRC is found to contain micro and meso‐porous structure along with high surface area (1899 m2 g−1) to endorse its suitability to this extend as an anode for LIBs and SIBs. The study illustrates the exploitation of waste‐to‐wealth attempt with an ultimate aim of recommending CRC as a potential anode for energy storage applications on the basis of low cost, cheap, eco‐benign electrode obtained from biodegradable cooked rice.

In an attempt to explore bio‐waste derived carbon for sulfur cathode and to exploit it further as an interlayer along with an interest to understand the individual and synergistic effect of bio‐carbon, jamun seed derived porous carbon (bio‐carbon) is deployed. Bio‐carbon contains micro‐pores and bestowed with high specific surface area of 2029 m2/g and pore volume of 1.2 ccm/g. Specifically, 60 wt.% S@bio‐carbon cathode with bio‐carbon interlayer exhibits 642 mAh/g at C/2 rate up to 75 cycles, which is two times higher than the capacity obtained without bio‐carbon interlayer. Notably, bio‐carbon interlayer leads to a 2–3 fold decrease in shuttle current and improves the performance of Li−S cell. Besides, effect of combination of bio‐carbon and Super‐P carbon as scaffold and/or as interlayer is studied, wherein bio‐carbon as scaffold and as interlayer outperforms in terms of capacity retention, better Coulombic efficiency and higher active material holding capability in Li−S batteries. Furthermore, even at a high rate of 3C, bio‐carbon/S‐60 cathode with bio‐carbon interlayer exhibits a capacity of 256 mAh/g, mainly due to the facile lithium kinetics of sulfur in the jamun seed derived bio‐carbon interlayer containing Li−S batteries.