Ultra‐Lightweight, High Power Density Lithium‐Ion Batteries

Abstract

Current fabrication methods for lithium-ion batteries impose a limit on how light a high power battery can be made. The lack of lightweight (< 300 mg), high power batteries is a significant constraint to the development of untethered micro-robots, wearable haptics, mobile computing, and biomedical applications. We have developed a laser micro-machining and assembly process which can produce batteries up to 30 times lighter than the lightest high power commercial cell, at comparable power densities (> 1 kW/kg). Our process is versatile and can be adapted to make custom geometries, miniature high voltage cells, and more, all while using a broad range of starting materials. We see this technology as a path to highly versatile miniature power sources, that will enable a wide range of small-scale applications.Existing fabrication technologies cannot be used to make lightweight, high power density lithium-ion batteries (< 300 mg). The need is increasing for these small, powerful batteries, as advances in fabrication techniques push the limits of miniaturization in robotics, [1] haptics, [2] wearable and biomedical technologies, [3] and mobile computing for the Internet of Things. [4] Unfortunately, current fabrication methods for lithium-ion cells force the end user to make a choice between high energy density and lightweight batteries (Figure 1(a)). Supercapacitors can provide even higher power density (> 10 kW/kg), but have very short discharge times (0.1-5 s), which limits the range of potential applications. [5] To push the limits of performance, we have developed a hybrid manufacturing approach which uses commercially available lithium-ion materials and a laser micro machining method to build lightweight (10-200 mg) high power density (> 1 kW/kg) batteries.Miniaturization of Li-ion batteries is limited by how the fabrication processes scale down, [5,6] Conventional Li-ion electrodes are made as planar films that are stacked into prismatic or cylindrical shapes. The stacked electrodes are infused with electrolyte, then sealed into a metallized film pouch, which prevents moisture from infiltrating into the battery. The materials and processes used to prevent moisture infiltration take up a significant amount of total battery weight, and scale unfavorably as the size of the battery is reduced. Furthermore, most nickel and aluminum commercial tabs weigh hundreds of milligrams, and need large areas for reliable welding to the electrodes. For high power devices, tabs and welds need to be oversized to avoid excessive resistive heating during fast charge or discharge. While several devices have been demonstrated to deliver high power at very small-scale (1-100 mg), the fabrication processes are either long duration, [7] or rely on unconventional materials, [8] or are difficult to replicate. [9] In addition, the most established processes to make lightweight batteries rely on thin-film, solid electrolyte chemistries, which suffer from rate limitations at room temperature, [10,11] To create lighter mesoscale power sources,...

Dual‐Carbon Batteries: Materials and Mechanism

“…For example, the devices (SC||1 m NaPF 6 ||NPHC) show the largest specific energy (245.7 Wh kg −1 ). [ 25 ] In addition, with rationally designed carbon electrodes to boost the ion transport kinetics, the DCBs can reach a highest specific power of up to 16 kW kg −1 , which is higher than commercial Li‐ion batteries (1 kW kg −1 ), [ 32 ] and even higher than most electrochemical capacitors (10 kW kg −1 ). [ 33 ] This high power performance is the consequence of the beneficial features of the carbon electrodes, such as hierarchically porous architecture, sheet‐like structure stacking (>15 nm in thickness), and large surface area (up to 2396 m 2 g −1 ).…”

Bipolar Electrodes for Next‐Generation Rechargeable Batteries

“…Compared with LABs and NMHBs with aqueous electrolytes, LIBs with organic electrolytes inherently process a higher voltage output in each cell. [4] When further combined with BEs, bipolar LIBs will be more competitive in the application of electric and hybrid electric vehicles while these electrified transportations need for the battery packs with working voltage of 300-500 V. [55] Figure 4. Typical strategies for enabling BEs in LIBs: a) Schematic illustration of the bipolar ASSBs and galvanostatic charge-discharge profiles of three-cell bipolar cells.…”

“…[2] Since then, rechargeable batteries have undergone countless improvements in electrode materials and cell configurations for higher specific energy, higher specific power, longer lifetime, better safety, and lower cost. [3,4] Up to now, such challenges have been progressively addressed by intensive scientific research into the development of novel battery chemistries, [5][6][7] such as high-capacity electroactive materials, electrolytes, and binders. In contrast, the role of a novel battery structure in boosting battery performance has been often overlooked in academia, and less effort has been devoted to its exploration.…”

Flexible and Wearable Power Sources for Next‐Generation Wearable Electronics

“…Design strategy of power supplies with small size and light weight calls for exploration of advanced materials and device fabrication methods. [73] One way to counter this issue is the utilization of nanostructured materials with highly exposed electrode active sites allowing both the movement of ions and electrons between the structures and along the conductive pathway. [60,74] For example, carbon-based nanomaterials including CNTs, carbon fiber, and graphene have been extensively used for electrode materials due to their high chemical stability, easy accessibility, nontoxicity, and simple processing.…”