Lithium–sulfur (Li–S) batteries are considered promising next-generation energy storage devices due to their low cost and high energy density (2600 W h kg⁻¹). However, the practical applicability of Li–S batteries is hindered by the insulating nature of sulfur cathodes, and the high solubility of polysulfides (Li₂S_x, 3 < x ≤ 8) which are formed during the electrochemical process. Integrating sulfur into the carbon host is an effective way to enhance the conductivity of the electrode which hampers the shuttling effect of the polysulfides. Here in this study, hierarchical porous carbon structures (HPC) are prepared from spent coffee waste (SCW) by the KOH activation process and are encapsulated with sulfur (SHPC) which increases the interaction between sulfur and carbon and enhances both the electronic and ionic conductivities. Further wrapping of SHPC with N-doped multi-walled carbon nanotubes (NCNTs) gives a SHPC-NCNT composite, which alleviates the shuttling of polysulfides by trapping them and ensures the required conductivity to the sulfur cathode during the Li⁺ reactions. When studied as a cathode material for Li–S batteries, the prepared cathode showed 664 and 532 mA h g⁻¹ specific capacities after 150 cycles at 0.2C and 0.5C, respectively. The stable cyclability and rate capability properties of SPHCNCNT suggest that the prepared sulfur composite is suitable as a cathode material for Li⁺ energy storage applications.

Silicon is a worthy substitute anode material for lithium-ion batteries because it offers high theoretical capacity and low working potentials vs. Li⁺/Li. However, immense volume changes and the low intrinsic conductivity of Si hampers its practical applications. In this study, nano/micro silicon particles are achieved by ball milling silicon mesh powder as a scalable process. Subsequent metal (Cu/Fe/Mn) doping into nano/micro silicon by low-temperature annealing, followed by high-temperature annealing with graphite, gives a metal-doped silicon/graphite composite. The obtained composites were studied as anodes for Li-ion batteries, and they delivered high reversible capacities of more than 1000 mAh g⁻¹ with improved Li⁺ diffusion properties. The full cells from these composite anodes vs. LiCoO₂ cathodes delivered suitable energy densities for Li⁺ storage applications. The enhanced electrochemical properties are accredited to the synergistic effect of metal doping and graphite addition to silicon and exhibit potential for suitable Li⁺ energy storage applications.

This work has developed a straightforward approach to obtaining NiO hollow structures by using Li₂O₂ as an easily removable template. The easy availability and electrochemically active nature of NiO have attracted researchers' attention as an anode electrode for Li-ion storage applications, including Li-ion secondary batteries (LIBs) and for Li-ion hybrid supercapacitors (LiHSCs; which offer higher power densities than LIBs without compromising energy density). However, NiO usage has been limited to its low reaction reversibility, poor conductivity, and conversion reaction capability. Recently, hollow nanostructured materials have attracted attention as efficient battery materials due to their fascinating structural features. This study presents a modified Li₂O₂-assisted method to obtain porous open 3D architectures of NiO nanostructures. The resultant hollow structures are electrochemically studied as an anode for a LIB, exhibiting excellent stability over hundreds of cycles. The result is recognized as one of the finest among NiO anodes reported. Also, NiO hollow structures studied as anodes for LiHSC devices fabricated with activated carbon cathodes exhibit an outstanding comprehensive electrochemical performance which is better than the typical LIB and supercapacitors.

Ni–MnO₂ hollow structures were synthesized and used as anodes for LICs, where they exhibited higher energy and power than the LIBs and SCs.