A Lithium‐Silicon Microbattery with Anode and Housing Directly Made from Semiconductor Grade Monocrystalline Si

Abstract

The development of systems that can economically convert and store electricity, preferably from solar energy, are urgently needed to address the numerous problems humankind is faced with in the centuries to come. [1] Lithium-ion batteries belong to the family of devices that take advantage of electrochemical reactions to store energy. [2][3][4][5][6] Because of its light weight and the fact that Li + ions are fast and small charge carriers, the development of lithium-ion batteries is a success story par excellence which was recognized by the Nobel prize in chemistry awarded to J. B. Goodenough, M. S. Whittingham, and A. Yoshino in 2019. In terms of energy density, the level of efficiency and cycleability, that is, the ability to be effectively charged and discharged, lithium-based batteries are superior not only to other battery chemistries but also to systems that rely on hydrogen conversion.So far, different types of lithium-based batteries, such as those using insertion hosts or conversion materials, have been presented. [7,8] Each year hundreds of studies appear that report on enhancements in materials performance by using either new or improved compounds or by taking benefit from clever morphologies. While much progress has been reported for the positive electrode, that is, the cathode side of a battery, [6] in most of the commercial batteries, graphite is still used as the main component of the anode material. [9] Modern anode composite materials tale advantage of a few weight percent of silicon to enhance the energy density of the battery. Of course, such approaches need a well-balanced cathode side to maximize the performance of the final full cell. The tempting lithium storage capability of 3579 mAh g −1 in the case of silicon is the reason behind why battery researchers dream of using Si as the electrochemically active anode material. [10] The use of pure Si, more or less independent of its morphology, is hindered by the fact that during lithiation the anode side experience an enormous volume expansion of up to 300%. [8] As a consequence, irreversible damages such as cracks and delamination drastically reduce the lifetime of such systems. Hence, bringing under control the cycling properties of Si is rather challenging as it suffers, in electrochemical terms, from low capacity retentions and poor Coulombic efficiencies. In particular, large per-cycle lithium losses are an issue when Si is Miniaturized and rechargeable energy storage systems, which easily power smart and (in vivo) sensors or the wirelessly networked transmitting devices of the so-called internet of things, are expected to open unprecedented ways for how information can be shared autonomously. On the macroscale, such battery-powered devices have already revolutionized our daily life by the use of mobile phones and portable computers. The eagerly-awaited advent of sufficiently powerful and long-living microbatteries will definitely make our lives more comfortable, especially in sectors such as medicine, security, autonomous driving or artif...

Design and manufacture of high-performance microbatteries: lithium and beyond

“…The small footprint (0.09 cm 2 ) Li-ion MB [ Figure 6E and F] presented an initial discharge capacity of 5.2 mWh cm -2 and a reversible capacity of 1.6 mWh cm -2 after 100 cycles with an average Coulombic efficiency of above 92%. Similarly, laser-patterned Si/TiN/Ge [63] , self-standing porous Si films [64] , plasma-etched Si/TiN/Sb nanorod arrays [65] , and dry etching Si towers [66] have also been reported for high-energy Li-ion MBs by accommodating the volume expansion of Si materials.…”

Microbatteries with twin-Swiss-rolls redefine performance limits in the sub-square millimeter range

“…4a compares the areal energy density of various microbatteries. 23,[45][46][47][48][49][50][51] Microbatteries have two common architectures: layered thin films and interdigitated electrode strips on the surface. [45][46][47] Despite the high attainable energy density, they are larger than 1 mm 2 because of difficulties in shrinking the size, such as maintaining the structural integrity with a small footprint and accuracy of layering down tiny films.…”

Miniaturized lithium-ion batteries for on-chip energy storage

“…Moreover, the SEI layer on the surface of Si particle bursts due to the volume expansion of Si, which makes Si react with electrolyte continuously, resulting in continuous consumption of active lithium and eventually capacity loss. [84][85] Sternad's group prepared micro-LIBs by using wafer-scale monocrystalline Si with a thickness of 50 μm as the anode (Fig. 12a).…”

“…They concluded that the formation of Li active lithium and eventually, in capacity loss. 84,85 Sternad's group prepared micro-LIBs by using wafer-scale monocrystalline Si with a thickness of 50 mm as the anode (Fig. 12a).…”

“…12a ). 85 This thickness of monocrystalline Si could effectively transport Li + from the surface to the interior of the block. It facilitated reducing the surface lithium concentration and thereby inhibiting the formation of Li 15 Si 4 .…”