Metal-halide perovskites are recognized as cutting-edge solar energy technology, boasting remarkable absorption capabilities, minimal environmental impact, and cost-effectiveness. This study delves into the structural stability, mechanical stability, and optoelectronic properties of lead-free halide perovskites, specifically XMgI₃ (X = Li/Na), by utilizing the CASTEP and WIEN2k software along with the GGA-PBE and Tran–Blaha modified Becke–Johnson (TB-mBJ) exchange–correlation functions to compare their electronic properties. The structural and mechanical stabilities were confirmed by assessing their tolerance factor and formation energy and by evaluating their elastic constants, respectively. Using the TB-mBJ exchange–correlation potential function, the calculated indirect band gap values for LiMgI₃ and NaMgI₃ were 2.474 and 2.556 eV, respectively. These band gaps are suitable for solar energy harvesting due to their broad optical absorption ranging from infrared to visible light. The partial density of states and the total density of states were determined to investigate the contribution of individual atoms. Consequently, this study can guide researchers focusing on the experimental synthesis of these materials at the laboratory scale for in-depth exploration, particularly in applications such as photovoltaics and various optoelectronic devices.

Heusler alloys, particularly half-Heusler (HH) compounds, exhibit exceptional potential for next-generation optoelectronic and renewable energy applications. In this study, we employ advanced density functional theory (DFT) to systematically investigate the structural, electronic, optical, thermodynamic, and thermoelectric properties of LiBeZ (Z = P/As) HH alloys. The band structure analysis using the mBJ exchange–correlation functional reveals that both LiBeP and LiBeAs exhibit indirect band gaps (1.82 eV and 1.66 eV, respectively), placing them in the ideal range for optoelectronic applications. Additionally, their broad-spectrum absorption and minimal reflectivity highlight their potential for efficient solar cells and optical sensor technologies. Moreover, as temperature rises, the enthalpy and entropy of the alloys increase, while Gibbs free energy decreases, indicating thermal stability. The alloys’ heat capacity follows the Debye model, making them suitable for thermoelectric and high-temperature electronic applications. Furthermore, from the thermoelectric properties analysis, it can be conferred that these materials have a high value of ZT_e and are suitable materials for thermoelectric devices. In conclusion, the predicted results strongly indicate that LiBeP and LiBeAs could serve as key materials for next-generation photonic, thermoelectric devices, and energy-harvesting devices. Future research should focus on experimental validation and device integration to fully harness their potential.

In this study we prepared potassium-ion batteries (KIBs) displaying high output voltage and, in turn, a high energy density, as replacements for lithium-ion batteries (LIBs). Organic electrode materials featuring void spaces and flexible structures can facilitate the mobility of K⁺ to enhance the performance of KIBs. We synthesized potassium maleamate (K-MA) from maleamic acid (MA) and applied as an anode material for KIBs and LIBs, with 1 M potassium bis(fluorosulfonyl)imide (KFSI) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in a mixture of ethylene carbonate and ethyl methyl carbonate (1:2, v/v) as respective electrolytes. The K-MA_KFSI anode underwent charging/discharging with carbonyl groups at low voltage, due to the K···O bond interaction weaker than Li···O. The K-MA_KFSI and K-MA_LiFSI anode materials delivered a capacity of 172 and 485 mA h g⁻¹ after 200 cycles at 0.1C rate, respectively. K-MA was capable of accepting one K⁺ in KIB, whereas it could accept two Li⁺ in a LIB. The superior recoveries performance of K-MA_LiFSI, K-MA_KFSI, and Super P_KFSI at rate of 0.1C were 320, 201, and 105 mA h g⁻¹, respectively. This implies the larger size of K⁺ can reversibly cycling at high rate.