In this work, a facile, wet chemical synthesis was utilized to achieve a series of lithium manganese oxide (LiMn₂O₄, (LMO) with 1–5%wt. graphene oxide (GO) composites. The average crystallite sizes estimated by the Rietveld method of LMO/GO nanocomposites were in the range of 18–27 nm. The electrochemical performance was studied using CR2013 coin-type cell batteries prepared from pristine LMO material and LMO modified with 5%wt. GO. Synthesized materials were tested as positive electrodes for Li-ion batteries in the voltage range between 3.0 and 4.3 V at room temperature. The specific discharge capacity after 100 cycles for LMO and LMO/5%wt. GO were 84 and 83 mAh g⁻¹, respectively. The LMO material modified with 5%wt. of graphene oxide flakes retained more than 91% of its initial specific capacity, as compared with the 86% of pristine LMO material.

Development in high-rate electrode materials capable of storing vast amounts of charge in a short duration to decrease charging time and increase power in lithium-ion batteries is an important challenge to address. Here, we introduce a synthesis strategy with a series of composition-controlled NMC cathodes, including LiNi_0.2Mn_0.6Co_0.2O₂(NMC262), LiNi_0.3Mn_0.5Co_0.2O₂(NMC352), and LiNi_0.4Mn_0.4Co_0.2O₂(NMC442). A very high-rate performance was achieved for Mn-rich LiNi_0.2Mn_0.6Co_0.2O₂ (NMC262). It has a very high initial discharge capacity of 285 mAh g⁻¹ when charged to 4.7 V at a current of 20 mA g⁻¹ and retains the capacity of 201 mAh g⁻¹ after 100 cycles. It also exhibits an excellent rate capability of 138, and 114 mAh g⁻¹ even at rates of 10 and 15 C (1 C = 240 mA g⁻¹). The high discharge capacities and excellent rate capabilities of Mn-rich LiNi_0.2Mn_0.6Co_0.2O₂ cathodes could be ascribed to their structural stability, controlled particle size, high surface area, and suppressed phase transformation from layered to spinel phases, due to low cation mixing and the higher oxidation state of manganese. The cathodic and anodic diffusion coefficient of the NMC262 electrode was determined to be around 4.76 × 10⁻¹⁰ cm² s⁻¹ and 2.1 × 10⁻¹⁰ cm² s⁻¹, respectively.

Ternary glassy electrolytes containing K₂S as a glass modifier and P₂S₅ as a network former are synthesized by introducing a new type of complex and asymmetric salt, potassium triflate (KOTf), to obtain unprecedented K⁺ ion conductivity at ambient temperature. The glasses are synthesized using a conventional quenching technique at a low temperature. In general, alkali ionic glassy electrolytes of ternary systems, specifically for Li⁺ and Na⁺ ion conductivity, have been studied with the addition of halide salts or oxysalts such as M₂SO₄, M₂SiO₄, M₃PO₄ (M = Li or Na), etc. We introduce a distinct and complex salt, potassium triflate (KOTf) with asymmetric anion, to the conventional glass modifier and former to synthesize K⁺-ion-conducting glassy electrolytes. Two series of glassy electrolytes with a ternary system of (0.9–x)K₂S-xP₂S₅-0.1KOTf (x = 0.15, 0.30, 0.45, 0.60, and 0.75) and z(K₂S-2P₂S₅)-yKOTf (y = 0.05, 0.10, 0.15, 0.20, and 0.25) on a straight line of z(K₂S-2P₂S₅) are studied for their K⁺ ionic conductivities by using electrochemical impedance spectroscopy (EIS). The composition 0.3K₂S-0.6P₂S₅-0.1KOTf is found to have the highest conductivity among the studied glassy electrolytes at ambient temperature with the value of 1.06 × 10⁻⁷ S cm⁻¹, which is the highest of all pure K⁺-ion-conducting glasses reported to date. Since the glass transition temperatures of the glasses are near 100 °C, as demonstrated by DSC, temperature-dependent conductivities are studied within the range of 25 to 100 °C to determine the activation energies. A Raman spectroscopic study shows the variation in the structural units ${PS}_4^{3-}{, P_2\mathrm{S}}_7^{4-}, {\mathrm{a}\mathrm{n}\mathrm{d} P_2\mathrm{S}}_6^{4-}$ of the network former for different glassy electrolytes. It seems that there is a role of ${P_2\mathrm{S}}_7^{4-}{ \mathrm{a}\mathrm{n}\mathrm{d} P_2\mathrm{S}}_6^{4-}$ in K⁺-ion conductivity in the glassy electrolytes because the spectroscopic results are compatible with the composition-dependent, room-temperature conductivity trend.

The application of oxygen-deficient perovskites (ODPs) has attracted interest as anode materials for lithium-ion batteries for their unique properties. One such material, CaSrFe_0.75Co_0.75Mn_0.5O_6-δ, has been studied extensively. The structure of CaSrFe_0.75Co_0.75Mn_0.5O_6-δ was investigated using various techniques, including Rietveld refinements with X-ray diffraction and neutron diffraction. Additionally, iodometric titration and X-ray photoelectron spectroscopy were employed to study the oxygen-deficiency amount and the transition metal’s oxidation states in the material. As an anode material, CaSrFe_0.75Co_0.75Mn_0.5O_6-δ exhibits promising performance. It delivers 393 mAhg⁻¹ of discharge capacity at a current density of 25 mAg⁻¹ after 100 cycles. Notably, this capacity surpasses both the theoretical graphite anode capacity (372 mAhg⁻¹) and that of the calcium analog reported previously. Furthermore, the electrochemical performance of CaSrFe_0.75Co_0.75Mn_0.5O_6-δ remains highly reversible across various current densities ranging from 25 to 500 mAg⁻¹. This suggests the material’s excellent stability and reversibility during charge–discharge cycles, showing its probable application as an anode for lithium-ion batteries. The mechanism of lithium intercalation and deintercalation within CaSrFe_0.75Co_0.75Mn_0.5O_6-δ has also been discussed. Understanding this mechanism is crucial for optimizing the battery’s performance and ensuring long-term stability. Overall, this study highlights the significant potential of oxygen-deficient perovskites, particularly CaSrFe_0.75Co_0.75Mn_0.5O_6-δ, for applications as an anode material for lithium-ion batteries, offering enhanced capacity and stability compared with traditional graphite-based anodes.