Structural Batteries Research Articles

Interface reinforced by polymer binder for expandable carbon fiber structural lithium-ion battery composites

Carbon fiber (CF) composite structural battery (SB) is a novel energy storage device that integrates electrochemical energy storage with mechanical load-bearing capability. Carbon fiber's inherent conjugated carbon network possesses excellent electronic conductivity, thus serving as a current collector for electrode active materials. The bonding between active materials and carbon fibers relies on their manufacturing processes, requiring optimization of their electrochemical performance and addressing the challenges of large-scale production. In this work, a LiFePO4/PEO-LiTFSI/CF composite cathode was fabricated using the direct coating method. Polyethylene oxide (PEO) acted as a binder to form a stable LiFePO4 (LFP) coating on the carbon fiber woven fabric, while multi-walled carbon nanotube (MWCNT) were employed to construct a conductive network. This significantly enhanced both the charge-discharge performance and interface stability of the composite cathode. This composite cathode achieved a first-cycle discharge-specific capacity of 133.21 mAh·g−1 at 0.1 C rate and retained 93.7 % of its capacity after 200 cycles at 1 C rate. Based on this composite cathode, multiple active material coatings were integrated onto a carbon fiber woven fabric to manufacture an expandable multi-cell structural battery. Its advantage lies in the ability of multiple battery cells to disperse stress under load, thus achieving a higher capacity retention rate under bending loads. The structural battery possesses a high degree of customizability, allowing for adjustment of the area, position, and quantity of active material coatings to meet the demands of practical conditions.

Fabrication and multiphysics numerical investigations of carbon fiber structural batteries

The structural battery (SB) that uses carbon fibers as anodes is a lightweight composite material battery integrating load bearing and energy storage. However, during usage, diffusion-induced stress may result in structural failure and a reduction in the battery capacity. In this paper, a laminated structural battery (LSB) was fabricated using carbon fiber cloth as an anode and collector and successfully powered LEDs. Then, based on this laminated structure, a multiphysics field model based on electrochemical-mechanical coupling is established for the analysis of complicated diffusion-induced stresses in carbon fibers. Following this model, researchers investigate the electro-chemo-mechanical behaviors and influencing factors of the SB and compare them with those of the lithium-ion battery (LIB). The results show that diffusion polarization in carbon fibers is aggravated by their lower diffusion coefficient, larger radius, and higher discharge rate; in both types of batteries, there is a higher tensile diffusion stress and a higher probability of failure at the surface of the anode active material than in the interior; a more uniform distribution of diffusion-induced stress on the surface of fibers at different locations; when discharging at a high rate, the SB capacity hardly reduces, and the high strength and relatively low diffusion-induced stress in the carbon fiber make it much safer, showing excellent electrochemical performance and resistance to failure due to diffusion-induced stress. This study demonstrates the feasibility of the fabrication and safety of carbon fiber structural batteries, which may potentially offer recommendations for the fabrication and use of novel SBs.

Advancing structural batteries: cost-efficient high-performance carbon fiber-coated LiFePO4 cathodes.

Structural batteries (SBs) have gained attention due to their ability to provide energy storage and structural support in vehicles and airplanes, using carbon fibers (CFs) as their main component. However, the development of high-performance carbon fiber-based cathode materials for structural batteries is currently limited. To address this issue, this study proposes a cost-efficient and straightforward method for creating a high-performance structural lithium iron phosphate (LiFePO4) positive electrode by coating carbon fibers at mild temperatures and pressures. The resulting cathode demonstrated a high LiFePO4 loading (at least 74%) and a smooth coating, as confirmed by X-ray spectroscopy, scanning electron microscopy, and Raman spectroscopy. This structural cathode exhibited a capacity of 144 mA h g-1 and 108 mA h g-1 at 0.1 C and 1.0 C, respectively. Additionally, the LiFePO4 cathode displayed excellent electrochemical properties, with a capacity retention of 96.4% at 0.33 C and 81.2% at 1.0 C after 300 cycles. Overall, this study presents a promising approach for fabricating high-performance structural batteries with enhanced energy storage and structural capabilities.

A carbon fiber lamina electrode based on macroporous epoxy with vertical ion channels for structural battery composites

Structural battery (SB) composites based on carbon fibers (CFs) are promising multifunctional composite materials to simultaneously realize load-bearing and electrical energy storage. Conventional structural battery electrolytes (SBEs) have bicontinuous phase microstructure characteristics, which makes a further considerable improvement in both mechanical and electrochemical performance of structural batteries rather challenging. Herein, a novel SBE with vertical ion channels in the form of patterned macropores was developed by photolithography based on the UV-initiated cationic polymerization, which was subsequently used in the fabrication of the CF half-cell lamina. The mechanical and electrochemical properties were characterized for both SBE and SB half-cells. The Young's modulus and ionic conductivity of the porous epoxy post-filled with liquid electrolyte were 1.2 GPa and 3.7 mS/cm, respectively, which exceeded the state-of-art multifunctional performances of bicontinuous SBEs. The specific capacity of the SB half-cell could reach 222 ± 10 mAh/g (2nd) at 0.17C, while the tensile modulus of the CF half-cell lamina was 66 ± 4 GPa (Vf = 22.5 %). This work could provide new insights into a microstructural design for structural batteries towards high multifunctional performances.

Bicontinuous Electrolytes via Thermally Initiated Polymerization for Structural Lithium Ion Batteries

Structural batteries (SBs) are a growing research subject worldwide. The idea is to provide massless energy by using a multifunctional material. This technology can provide a new pathway in electri ...