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Multinary metal chalcogenides hold considerable promise for high-energy potassium storage due to their numerous redox reactions. However, challenges arise from issues such as volume expansion and sluggish kinetics. Here, a design featuring a layered ternary Bi 0.4 Sb 1.6 Te 3 anchored on graphene layers as a composite anode, where Bi atoms act as a lattice softening agent on Sb, is presented. Benefiting from the lattice arrangement in Bi 0.4 Sb 1.6 Te 3 and structure, Bi 0.4 Sb 1.6 Te 3 /graphene exhibits a mitigated expansion of 28% during the potassiation/depotassiation process and demonstrates facile K + ion transfer kinetics, enabling long-term durability of 500 cycles at various high rates. Operando synchrotron diffraction patterns and spectroscopies including in situ Raman, ex situ adsorption, and X-ray photoelectron reveal multiple conversion and alloying/dealloying reactions for potassium storage at the atomic level. In addition, both theoretical calculations and electrochemical examinations elucidate the K + migration pathways and indicate a reduction in energy barriers within Bi 0.4 Sb 1.6 Te 3 /graphene, thereby suggesting enhanced diffusion kinetics for K + . These findings provide insight in the design of durable high-energy multinary tellurides for potassium storage., (© 2024 Wiley‐VCH GmbH.)

Lead-free layered double perovskite nanocrystals (NCs), i.e., Cs 4 M(II)M(III) 2 Cl 12 , have recently attracted increasing attention for potential optoelectronic applications due to their low toxicity, direct bandgap nature, and high structural stability. However, the low photoluminescence quantum yield (PLQY, <1%) or even no observed emissions at room temperature have severely blocked the further development of this type of lead-free halide perovskites. Herein, two new layered perovskites, Cs 4 CoIn 2 Cl 12 (CCoI) and Cs 4 ZnIn 2 Cl 12 (CZnI), are successfully synthesized at the nanoscale based on previously reported Cs 4 CuIn 2 Cl 12 (CCuI) NCs, by tuning the M(II) site with different transition metal ions for lattice tailoring. Benefiting from the formation of more self-trapped excitons (STEs) in the distorted lattices, CCoI and CZnI NCs exhibit significantly strengthened STE emissions toward white light compared to the case of almost non-emissive CCuI NCs, by achieving PLQYs of 4.3% and 11.4% respectively. The theoretical and experimental results hint that CCoI and CZnI NCs possess much lower lattice deformation energies than that of reference CCuI NCs, which are favorable for the recombination of as-formed STEs in a radiative way. This work proposes an effective strategy of lattice engineering to boost the photoluminescent properties of lead-free layered double perovskites for their future warm white light-emitting applications., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)