Xiaosi Zhou

Layered manganese-based oxides for potassium-ion batteries (PIBs) suffer from severe structural degradation, primarily due to irreversible phase transitions, Jahn–Teller distortion, and sluggish K+ diffusion kinetics. Here, we propose an alkali-metal site riveting strategy by selectively incorporating oversized Rb+ ions into the prismatic sites of P2-type K0.55Mn0.8Ni0.1T0.1O2. The introduced Rb+ acts as a rigid pillar, expanding the interlayer spacing and reinforcing adjacent transition-metal–oxygen (TM–O) bonds. This synergistic modulation not only widens the two-dimensional diffusion channels for rapid K+ transport but also effectively suppresses the detrimental P2–P′2 phase transition and mitigates Jahn–Teller distortion of Mn3+. Consequently, the optimized K0.55Rb0.025Mn0.8Ni0.1Ti0.1O2 cathode delivers a high reversible capacity of 105.3 mAh g–1 at a current density of 20 mA g–1, outstanding rate capability (56.1 mAh g–1 at 500 mA g–1), and long-term cycling stability with 82.1% capacity retention after 500 cycles. Furthermore, a pouch cell paired with a soft carbon anode achieves 81.3% capacity retention over 300 cycles. This work demonstrates that anchoring oversized cations in alkali-metal layers provides a universal and effective strategy toward near-zero-strain layered oxide cathodes for advanced PIBs.

Magnesium‐ion batteries (MIBs), as a highly promising next‐generation energy storage technology, benefit from the high theoretical volumetric capacity (3833 mAh L ⁻¹ ) of magnesium metal and its intrinsic safety. However, its commercialization is still hindered by sluggish de‐solvation kinetics during cycling, which prolongs the activation periods to reach maximum capacity and impairs rate performance. To overcome this bottleneck, we add 4‐ethyl‐4‐methylmorpholinium cation (EMM ⁺ ) as an additive into the conventional all‐phenyl‐complex (APC) electrolyte. Density functional theory computations confirm that EMM ⁺ shows a strong affinity for chloride ions (−0.513 eV), which weakens the Mg–Cl coordination and, thus promotes Mg ²⁺ de‐solvation. In CuS‐based MIBs, the modified APC‐EMM electrolyte eliminates the activation cycles that are required with pure APC, and achieves a high specific capacity of 405.1 mAh g ⁻¹ at 100 mA g ⁻¹ , while maintaining excellent rate performance (220.1 mAh g ⁻¹ at 1 A g ⁻¹ ). Notably, this electrolyte also shows significant improvements in capacity, activation kinetics, and cycling stability when applied to other cathode materials, including CuSe, Cu ₇ Te ₄ , Mo ₆ S ₈ , and perylene‐3,4,9,10‐tetracarboxylic dianhydride. This study establishes a de‐solvation‐accelerated electrolyte design concept as a universal paradigm for the development of high‐performance MIBs.

Magnesium‐ion batteries (MIBs), as a highly promising next‐generation energy storage technology, benefit from the high theoretical volumetric capacity (3833 mAh L ⁻¹ ) of magnesium metal and its intrinsic safety. However, its commercialization is still hindered by sluggish de‐solvation kinetics during cycling, which prolongs the activation periods to reach maximum capacity and impairs rate performance. To overcome this bottleneck, we add 4‐ethyl‐4‐methylmorpholinium cation (EMM ⁺ ) as an additive into the conventional all‐phenyl‐complex (APC) electrolyte. Density functional theory computations confirm that EMM ⁺ shows a strong affinity for chloride ions (−0.513 eV), which weakens the Mg–Cl coordination and, thus promotes Mg ²⁺ de‐solvation. In CuS‐based MIBs, the modified APC‐EMM electrolyte eliminates the activation cycles that are required with pure APC, and achieves a high specific capacity of 405.1 mAh g ⁻¹ at 100 mA g ⁻¹ , while maintaining excellent rate performance (220.1 mAh g ⁻¹ at 1 A g ⁻¹ ). Notably, this electrolyte also shows significant improvements in capacity, activation kinetics, and cycling stability when applied to other cathode materials, including CuSe, Cu ₇ Te ₄ , Mo ₆ S ₈ , and perylene‐3,4,9,10‐tetracarboxylic dianhydride. This study establishes a de‐solvation‐accelerated electrolyte design concept as a universal paradigm for the development of high‐performance MIBs.

Cobalt‐based Prussian blue analogs (CoHCC) have emerged as highly promising anode materials for potassium‐ion batteries due to their open framework structure, suitable potassium‐ion insertion potential, and high theoretical capacity. However, the intrinsically low electronic conductivity of CoHCC, its tendency for particle agglomeration during traditional synthesis, and the uncontrollable particle size have severely restricted its potassium‐ion storage performance. This study reports a hydroxylated MXene‐assisted in situ synthesis strategy for constructing ultrafine CoHCC nanoparticles anchored on a Ti ₃ C ₂ T _x MXene substrate (CoHCC@MX) as a high‐performance potassium‐ion battery anode. The –OH groups on the MXene surface serve as effective anchoring sites, enabling uniform nucleation and growth of CoHCC nanocrystals while preventing particle aggregation. The MXene substrate forms a continuous metallic conductive network, significantly enhancing electron transport and alleviating the poor conductivity of pristine CoHCC. Density functional theory calculations indicate strong interfacial electronic coupling between the –OH‐functionalized MXene and CoHCC, which not only stabilizes the composite structure but also inhibits the dissolution of active materials. The optimized CoHCC@MX‐1.0 composite anode delivers a high reversible capacity of 289.3 mAh g ⁻¹ after 1000 cycles at 500 mA g ⁻¹ , and exhibits excellent rate performance. When paired with a K _1.92 Fe[Fe(CN) ₆ ] _0.94 ·0.5H ₂ O cathode to assemble a full cell, it achieves a high energy density of 228.1 Wh kg ⁻¹ and retains 80.8% of its energy after 600 cycles. This work underlines the crucial role of functionalized MXene in interface engineering, providing a promising design strategy for advanced potassium‐ion storage materials.

The long‐range AA‐stacking structures present in most covalent organic frameworks (COFs) result in poor utilization of redox‐active sites and suboptimal electrochemical performance. Herein, we report a metallized COF (Cu@MCOF‐D) by pre‐synthesizing cyclic trinuclear copper clusters (Cu ₃ ) and integrating them with 2,6‐diaminoanthraquinone (DAAQ). Formation energy calculations confirm that the material possesses a thermodynamically stable AB‐stacking structure, which effectively alleviates interlayer K ⁺ adsorption shielding and optimizes the interlayer K ⁺ diffusion kinetics. Results from ex situ transmission electron microscopy analyses under different charge/discharge states indicate that Cu ₃ exhibits strong adsorption capability toward FSI ⁻ , while the ‒C═O/‒C═N‒ groups chemically bind K ⁺ , and together they synergistically enable dual‐ion storage. When applied as potassium‐ion battery (PIB) anode, the reduced diffusion barrier allows a high reversible capacity of 153.8 mAh g ⁻¹ at 20.0 A g ⁻¹ , and delivers 96.8% capacity retention after 6500 cycles at 5.0 A g ⁻¹ , demonstrating exceptional long‐term K ⁺ storage stability. In PIB full cells using potassium iron hexacyanoferrate as the cathode, a high energy density of up to 197.5 Wh kg ⁻¹ is achieved. Furthermore, by employing 3,4,9,10‐perylenetetracarboxylic dianhydride heat‐treated at 450°C as the cathode, outstanding cycling stability is realized, with a capacity retention of 93.2% after 2000 cycles.

The long‐range AA‐stacking structures present in most covalent organic frameworks (COFs) result in poor utilization of redox‐active sites and suboptimal electrochemical performance. Herein, we report a metallized COF (Cu@MCOF‐D) by pre‐synthesizing cyclic trinuclear copper clusters (Cu ₃ ) and integrating them with 2,6‐diaminoanthraquinone (DAAQ). Formation energy calculations confirm that the material possesses a thermodynamically stable AB‐stacking structure, which effectively alleviates interlayer K ⁺ adsorption shielding and optimizes the interlayer K ⁺ diffusion kinetics. Results from ex situ transmission electron microscopy analyses under different charge/discharge states indicate that Cu ₃ exhibits strong adsorption capability toward FSI ⁻ , while the ‒C═O/‒C═N‒ groups chemically bind K ⁺ , and together they synergistically enable dual‐ion storage. When applied as potassium‐ion battery (PIB) anode, the reduced diffusion barrier allows a high reversible capacity of 153.8 mAh g ⁻¹ at 20.0 A g ⁻¹ , and delivers 96.8% capacity retention after 6500 cycles at 5.0 A g ⁻¹ , demonstrating exceptional long‐term K ⁺ storage stability. In PIB full cells using potassium iron hexacyanoferrate as the cathode, a high energy density of up to 197.5 Wh kg ⁻¹ is achieved. Furthermore, by employing 3,4,9,10‐perylenetetracarboxylic dianhydride heat‐treated at 450°C as the cathode, outstanding cycling stability is realized, with a capacity retention of 93.2% after 2000 cycles.