Seungmin Hyun

Polymer binders are crucial in electrodes, as they both hold together active material particles and conductive additives and firmly bond the composite to the current collector. Thus, they maintain the mechanical integrity of battery systems and stabilize electron pathways during repeated cycling. However, mechanical stresses such as bending, stretching, and volumetric changes can generate internal fractures that disrupt conductive pathways, detach active particles, and compromise electrode–collector interfaces, ultimately degrading electrochemical performance. Although conventional binders provide adequate adhesion and processability, they are inherently passive and cannot respond to such structural damage. Once cracks form or particle contact is lost, they cannot re-establish connectivity, causing irreversible capacity loss. In contrast, self-healing polymer binders (SHPBs), a new class of smart materials, can autonomously repair the mechanical and structural damage incurred during battery operation. Their unique ability to re-establish chemical or physical bonds within the polymer matrix enables them to effectively mend microcracks, preserving electrode cohesion and conductive networks. These adaptive properties offer several compelling advantages, e.g., improved mechanical resilience and extended cycle life. They also mitigate internal short circuits and potential thermal runaway, enhancing safety. Furthermore, SHPBs support consistent electrochemical performance by maintaining interfacial integrity among active materials, conductive additives, and current collectors. This reduces the need to maintain or replace batteries and/or their components, improving the cost-effectiveness and environmental sustainability of energy storage systems. In contrast to earlier reviews that focused on binders for Si-based lithium-ion batteries, this review explores recent advancements in the molecular design strategies and healing mechanisms of SHPBs, and their impact on cell-level performance across battery platforms such as lithium-ion, lithium–sulfur, and emerging sodium-based batteries. We discuss critical challenges, key future research directions, and opportunities for advancing resilient, safe, high-energy-density batteries with prolonged cycle lives.

Compositing carbon‐based materials with different properties can significantly improve the energy density of lithium‐ion batteries for applications that require high power, such as electric vehicles, owing to their effective current distribution. Nevertheless, the chemical reaction is not uniform throughout the entire depth of conventionally blended electrodes. This study proposes a hybrid patterned bilayer anode that comprises a blended layer of spherical crystalline graphite (SCG) and soft carbon and a single layer of SCG alone, which maintains a stable ionic reaction at the electrode surface and improves ion transport. This bilayer anode has a smaller, more uniform solid electrolyte interphase layer that is more evenly distributed throughout the electrode compared with the blended electrode. The electrode pattern interfaces, which are optimized by controlling the pattern size, ensure excellent mechanical adhesion and low internal resistance. Consequently, the patterned bilayer half‐cell achieves a high‐capacity retention of 85.9% after 500 charge–discharge cycles at 1 C. The full cell also attains an energy density of 178.7 Wh kg⁻¹ with fast discharging at 10 C, which is 2.3 times higher than that of the single‐layer SCG electrode.

Geometrically multifunctional structures inspired by nature can address the challenges in the development of soft robotics. A bioinspired structure based on origami and kirigami can significantly enhance the stretchability and reliability of soft robots. This study proposes a novel structure with individual, overlapping units, similar to snake scales that can be used to construct shape-morphing batteries for untethered soft robots. The structure is created by folding well-defined, two-dimensional patterns with cutouts. The folding lines mimic the hinge structure of snakeskin, enabling stable deformations without mechanical damage to rigid cells. The structure realizes multi-axial deformability and a zero Poisson's ratio without off-axis distortion to the loading axis. Moreover, to maximize areal density, the optimal cell shape is designed as a hexagon. The structure is applied to a stretchable Li-ion battery, constructed to form an arrangement of electrically interconnected, hexagonal pouch cells. In situ electrochemical characterization and numerical simulation confirm that the shape-morphing scale battery maintains its performance under dynamic deformation with a 90% stretching ratio and 10-mm-radius bending curve, guaranteeing a long-lasting charging/discharging cycle life during cyclic bending and stretching (exceeding 36,000 cycles). Finally, the shape-morphing energy storage device is applied to movable robots, mimicking crawling and slithering, to demonstrate excellent conformability and deformability.

Lithium primary cells have the advantages of stable operating voltage, high energy density, long storage life, low discharge rate, and wide operating temperature range. Although not as reusable as lithium ion batteries, lithium primary batteries have been used in various fields, such as medical, environmental, and military, which require a small amount of current for a lengthy period or combined safety. In this study, MnO₂/CFx hybrid primary batteries comprising manganese dioxide and carbon fluoride (CFx), the main cathode materials of lithium primary battery, were fabricated and their discharge performance was measured. The discharge curve of the Li-MnO₂/CFx cells was classified into the MnO₂ phase and the CFx phase at low C-Rate. As the ratio of CFx increases, the discharge capacity of the battery increases, but the rate characteristics decreases. Considering all parameters such as capacity, rate capability, and temperature, the optimum amount of CFx doping was 70%. The mixing ratio of CFx/MnO₂ hybrid cathode can remarkably control the electrochemical performances and this kind of mixing ratio is expected to improve the electrochemical performances.