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Cobalt-free (Co-free) and nickel-rich (Ni-rich) cathode materials have attracted significant attention and undergone extensive studies due to their affordability and superior energy density. However, the commercialization of these Co-free materials is hindered by challenges such as cation disorder, irreversible phase changes, and inadequate high-voltage performance. To overcome these challenges, a Co-free ternary cathode material of Mg/Al double-pillared LiNiO 2 (NMA) synthesized via a wet-coating and lithiation-sintering technique is proposed. Fundamental studies reveal that Mg and Al have the potential to form a distinctive double-pillar structure within the layered cathode, enhancing its structural stability. To be specific, the strategic placement of Mg and Al in Li and Ni layers, respectively, effectively reduces Li + /Ni 2+ disorder and prevents irreversible phase transitions. Additionally, the inclusion of Mg and Al refines the primary grains and compacts the secondary grains in the cathode material, reducing stress from cyclic usage and preventing material cracking, thereby mitigating electrolyte erosion. As a result, NMA demonstrates exceptional electrochemical performance under a high charge cutoff voltage of 4.6 V. It maintains 70% of initial specific capacity after 500 cycles at 1 C and exhibits excellent rate performance, with a capacity of 162 mAh g -1 at 5 C and 149 mAh g -1 at 10 C. As a whole, the produced NMA achieves a high structural stability in cases of excessive delithiation, providing a groundbreaking solution for the development of cost-effective and high-energy-density cathode materials for lithium-ion batteries.

All-solid-state lithium metal batteries (ASSLMBs), as a candidate for advanced energy storage devices, invite an abundance of interest due to the merits of high specific energy density and eminent safety. Nevertheless, issues of overwhelming lithium dendrite growth and poor interfacial contact still limit the practical application of ASSLMBs. Herein, we designed and fabricated a double-layer composite solid electrolyte (CSE), namely, PVDF-LiTFSI-Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 /PVDF-LiTFSI- h- BN (denoted as PLLB), for ASSLMBs. The reduction-tolerant PVDF-LiTFSI- h- BN (denoted as PLB) layer of the CSE tightly contacts with the Li metal anode to avoid the reduction of LATP by the electrode and participates in the formation of a stable SEI film using Li 3 N. Meanwhile, the oxidation-resistance and ion-conductive PVDF-LiTFSI- LATP (denoted as PLA) layer facing the cathode can reduce the interfacial impedance by facilitating ionic migration. With the synergistic effect of PLA and PLB, the Li/Li symmetric cells with sandwich-type electrolytes (PLB/PLA/PLB) can operate for 1500 h with ultralong cycling stability at 0.1 mA cm -2 . Additionally, the LiFePO 4 /Li cell with PLLB maintains satisfactory capacity retention of 88.2% after 250 cycles. This novel double-layer electrolyte offers an effective approach to achieving fully commercialized ASSLMBs.

The single-crystalline Ni-rich cathode has aroused much attention for extenuating the cycling and safety crises in comparison to the polycrystalline cathode. However, planar gliding and kinetic hindrance hinder its chemo-mechanical properties with cycling, which induce delamination cracking and damage the mechanical integrity in single crystals. Herein, a robust Li 2.64 (Sc 0.9 Ti 0.1 ) 2 (PO 4 ) 3 (LSTP) ion/electron conductive network was constructed to decorate single-crystal LiNi 0.9 Co 0.05 Mn 0.05 O 2 (SC90) particles. Via physicochemical characterizations and theoretical calculations, this LSTP coating that evenly grows on the SC90 particle with good lattice matching and strong bonding effectively restricts the anisotropic lattice collapse along the c-axis and the cation mixing activity of SC90, thus suppressing planar gliding and delamination cracking during repeated high-voltage lithiation/delithiation processes. Moreover, such a 3D LSTP network can also facilitate the lithium-ion transport and prevent the electrolyte's corrosion, lightening the kinetic hindrance and triggering the surface phase transformation. Combined with the Li metal anode, the LSTP-modified SC90 cell exhibits a desirable capacity retention of 90.5% at 5 C after 300 cycles and stabilizes the operation at 4.3/4.5 V. Our results provide surface modification engineering to mitigate planar gliding and kinetic hindrance of the single-crystalline ultra-high Ni-rich cathode, which inspires peers to design other layered cathode materials.

P2-type Na 0.67 MnO 2 with a stable structure and an open framework can provide numerous channels for fast Na + de/intercalation, for which it is considered to be advantageous in application of the cathode material for Na-ion batteries. However, the complex phase transition occurring during cycling and the lattice distortion triggered by the Jahn-Teller effect severely restrict its development. Herein, the modified Na 0.67 MnO 2 with Cu or Fe single-element doping as well as Cu and Fe double-element doping was synthesized by the sol-gel method, and the effects of doping on the crystal structure and electrochemical performances of Na 0.67 MnO 2 were studied. It was demonstrated that the phase of the material did not change after the introduction of Cu and Fe elements, and the cycling stability and rate performance were greatly improved by Cu and Fe double-doping owing to their synergistic effect. The Na 0.67 Mn 0.92 Fe 0.04 Cu 0.04 O 2 (NMFCO) cathode delivers discharge specific capacities of 110.5 mA h g -1 at 5 C and 91.8 mA h g -1 at 10 C and exhibits the high-capacity retention of 94.35% at 1 C and 90.68% at 5 C after 100 cycles. Overall, this study offers a guiding direction for accelerating the modification of P2-type Na 0.67 MnO 2 as a cathode active material for high performance Na-ion batteries.

Li-rich Mn-based-layered oxides are considered to be the most felicitous cathode material candidates for commercial application of lithium-ion batteries on account of high energy density. Nevertheless, defects containing an unsatisfactory initial Coulombic efficiency and rapid voltage decay seriously impede their practical utilization. Herein, a coating layer with three distinct crystalline states are employed as a coating layer to modify Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 , respectively, and the effects of coating layers with distinct crystalline states on the crystal structure, diffusion kinetics, and cell performance of host materials are further explored. A coating layer with high crystallinity enables mitigatory voltage decay and better cyclic stability of materials, while a coating layer with planar defects facilitates Li + transfer and enhances the rate performance of materials. Consequently, optimizing the crystalline state of coating substances is critical for preferable surface modification.