Sodium, due to its abundance in the Earth’s crust (2.74%), is 421 times that of lithium (0.0065%), making sodium-metal batteries (SMBs) a promising supplement to lithium-based systems. The intrinsic properties of sodium metal, including kinetic and thermodynamic instabilities during plating and stripping, however, lead to dendrite growth, internal shorts, and serious safety issues. In this work, a functional polyethylene (PE) based separator decorated with a uniform layer of bamboo carbon (BC) is prepared using a simple blade casting method. Compared with the pristine PE separator, the BC-modified separator shows better electrolyte wettability and uniform biomimetic channels. The coated BC promotes uniform sodium-ion flux and even sodium deposition, effectively suppressing dendrite formation and greatly enhancing cycling stability. The BC-modified PE separator mitigates the tip effect at sodium metal defects, enabling stable performance of symmetric cells. In electrochemical tests, sodium symmetric cells with this separator operated stably for over 450 h at 0.5 mA·cm⁻² and 0.5 mAh·cm⁻². Moreover, Na|PE-BC|sodium iron pyrophosphate phosphate (NFPP) full cells retained over 98% capacity after 1000 cycles at 1 C (1 C = 129 mA·g⁻¹), over 90% after 2000 cycles at 5 C, and over 70% after 6000 cycles at a high rate of 10 C. Even with a high cathode loading of 7.1 mg·cm⁻², the full cells maintained 90% capacity for more than 300 cycles. This work offers a simple and effective modification of commercial PE separators using renewable, low-cost bamboo carbon, providing a practical and sustainable route toward highly stable, high-loading sodium-metal batteries.

LiNi_0.5Mn_1.5O₄ (LNMO) with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage (~ 5 V) lithium-ion batteries. Nevertheless, the elevated operational voltage of LNMO gives rise to pronounced interfacial interactions between the distorted surface lattices characterized by Jahn–Teller (J–T) distortions and the electrolyte constituents. Herein, a localized crystallized coherent LaNiO₃ and surface passivated Li₃PO₄ layer is deposited on LNMO via a one-step calcination process. As evidenced by transmission electron microscopy (TEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and density functional theory (DFT) calculation, the epitaxial growth of LaNiO₃ along the LNMO lattice can effectively stabilize the structure and inhibit irreversible phase transitions, and the Li₃PO₄ surface coating can prevent the chemical reaction between HF and transition metals without sacrificing the electrochemical activity. In addition, the ionic conductive Li₃PO₄ and atomic wetting inter-layer enables fast charge transfer transport property. Consequently, the LNMO material enabled by the lattice bonding and surface passivating features, demonstrates high performance at high current densities and good capacity retention during long-term test. The rational design of interface coherent engineering and surface coating layers of the LNMO cathode material offers a new perspective for the practical application of high-voltage lithium-ion batteries.

To meet the growing demand for wearable smart electronic devices, the development of flexible lithium-ion batteries (LIBs) is essential. Silicon is an ideal candidate for the anode material of flexible lithium-ion batteries due to its high specific capacity, low working potential, and earth abundance. The largest challenge in developing a flexible silicon anode is how to maintain structural integrity and ensure stable electrochemical reactions during external deformation. In this work, we propose a novel design for fabricating core–shell electrodes based on a copper nanowire (CuNW) array core and magnetron sputtered Si/C shell. The nanowire array structure has characteristics of bending under longitudinal stress and twisting under transverse stress, which helps to maintain the mechanical stability of the structure during electrode bending and cycling. The low-temperature annealing generates a small amount of Cu₃Si alloy, which enhances the connection strength between Si and the conductive network and solves the poor conductivity problem of Si, which is known as a semiconductor material. This unique configuration design of CuNW@Si@C-400 °C leads to stable long cycle performance of 1109 mAh∙g⁻¹ after 1000 cycles and excellent rate performance of 500 mAh∙g⁻¹ at a current density of 10 A∙g⁻¹. Furthermore, the CuNW@Si@C-400 °C||LiFePO₄ (LFP) full battery demonstrates excellent flexibility, with a capacity retention of more than 96% after 100 bends. This study provides a promising strategy for the development of flexible lithium-ion batteries.