Development of Magnesium Anode‐Based Transient Primary Batteries

Abstract

Biodegradable primary batteries, also known as transient batteries, are essential to realize autonomous biodegradable electronic devices with high performance and advanced functionality. In this work, magnesium, copper, iron, and zinc – metals that exist as trace elements in the human body – were tested as materials for biomedical transient electronic devices. Different full cell combinations of Mg and X (where X = Cu, Fe, and Zn and the anodized form of the metals) with phosphate buffered saline (PBS) as electrolyte were studied. To form the cathodes, metal foils were anodized galvanostatically at a current density of 2.0 mA cm −2 for 30 mins. Electrochemical measurements were then conducted for each electrode combination to evaluate full cell battery performance. Results showed that the Mg−Cu anodized chemistry has the highest power density at 0.99 mW/cm 2 . Nominal operating voltages of 1.26 V for the first 0.50 h and 0.63 V for the next 3.7 h were observed for Mg−Cu anodized which was discharged at a current density of 0.70 mA cm −2 . Among the materials tested, Mg−Cu anodized exhibited the best discharge performance with an average specific capacity of 2.94 mAh cm −2 , which is comparable to previous reports on transient batteries.

Body-Fluid-Driven Magnesium–Molybdenum Battery for Wound Healing

“…The electrochemical reactions of the battery in PBS are shown in eqs –. , anodic reaction: ⁣ Mg → Mg 2 + + 2 e − ⁣ E θ = − 2.370 V vs SHE cathodic reaction: ⁣ O 2 + 2 H 2 O + 4 e − → 4 OH − ⁣ E θ = 0.400 V vs SHE ( ORR type ) or 2 H 2 O + 2 e − → H 2 + 2 OH − ⁣ E θ = − 0.830…”

“…In contrast, biometal-based batteries ,− exhibit the advantages of stable electrical signals and high discharge capacity for sustained stimulation. It should be noted that ES induced by an exogenous physical stimulus ,,, needs to reach 10–200 mV mm –1 to boost wound healing effectively. ,,− Within such an ES intensity range, the increase in the stimulus intensity and time both favor a healing effect. − Magnesium (Mg), with excellent biocompatibility, − possesses both a low standard potential ( E Mg/Mg 2+ = −2.370 V vs SHE) and a high theoretical capacity density (2205 mAh g –1 ), allowing more satisfying ES to meet the demand for its intensity and stimulation duration, and could act as an ideal metal-based battery for IMDs.…”

Aqueous Batteries for Human Body Electronic Devices

“…As an electrolyte for degradable batteries, it should not only serve the above purpose, but also be biocompatible and degradable and is mainly divided into liquid electrolyte (such as PBS and SBF) and quasi-solid electrolyte (such as polymer electrolyte). The main components of PBS include Na 2 HPO 4 , KH 2 PO 4 , NaCl, and KCl, and the main components of SBF include KH 2 PO 4 , CaCl 2 , NaHCO 3 , NaCl, MgCl 2 , and Tris, both of which have a pH of approximately 7.4, are compatible with batteries, and are commonly used as electrolytes in biodegradable batteries. , PBS and SBF have pH buffering effect, so they can effectively prevent sudden changes in pH when used as an electrolyte in batteries featuring ORR or HER as the cathodic reaction mechanism. However, since the solvent of PBS and SBF is H 2 O, it is highly corrosive to the anodes of magnesium- and zinc-based batteries, which is detrimental to the stability of the batteries in discharge .…”

Advances and Challenges in Electrolyte Development for Magnesium–Sulfur Batteries: A Comprehensive Review

“…Divalent Mg 2+ enables two electron transfers per Mg atom, resulting in a high theoretical specific capacity of 2205 mAh g −1 [ 16 , 17 , 18 ]. Considering the density of magnesium, the Mg anode enables a high volumetric capacity of 3833 mAh mL −1 , which is almost double that of lithium (2062 mAh mL −1 ) [ 17 , 19 , 20 , 21 , 22 ]. Moreover, a Mg anode displays advantages such as low cost, high Earth abundance, and easy operation under air [ 23 , 24 , 25 ].…”