Abstract LiMn 2 O 4 spinel is emerging as a promising cathode material for lithium‐ion batteries, largely due to its open framework that facilitates Li + diffusion and excellent rate performance. However, the charge–discharge cycling of the LiMn 2 O 4 cathode leads to severe structural degradation and rapid capacity decay. Here, an electrochemical activation strategy is introduced, employing a facile galvano‐potentiostatic charging operation, to restore the lost capacity of LiMn 2 O 4 cathode without damaging the battery configuration. With an electrochemical activation strategy, the cycle life of the LiMn 2 O 4 cathode is extended from an initial 1500 to an impressive 14 000 cycles at a 5C rate with Li metal as the anode, while increasing the total discharge energy by ten times. Remarkably, the electrochemical activation enhances the diffusion kinetics of Li + , with the diffusion coefficient experiencing a 37.2% increase. Further investigation reveals that this improvement in capacity and diffusion kinetics results from a transformation of the redox‐inert LiMnO 2 rocksalt layer on the surface of degraded cathodes back into active spinel. This transformation is confirmed through electron microscopy and corroborated by density functional theory simulations. Moreover, the viability of this electrochemical activation strategy has been demonstrated in pouch cell configurations with Li metal as the anode, underscoring its potential for broader application.
In article number 2007548, Guanjie He, Ivan P. Parkin, and co-workers review the recent developments in flexible zinc-ion batteries, regarding materials, fabrication strategies, and current issues. Considering the materials cost, life-cycle analysis, and realistic application scenarios, insights from lab research to commercialization are proposed. Their innovative ranking index provides a quantitative method to analyze the feasibility of flexible zinc-ion batteries.
Aqueous zinc-ion batteries (AZIBs) have the potential to be utilized in a grid-scale energy storage system owing to their high energy density and cost-effective properties. However, the dissolution of cathode materials and the irreversible extraction of preintercalated metal ions in the electrode materials restrict the stability of AZIBs. Herein, a cathode-stabilized ZIB strategy is reported based on a natural biomass polymer sodium alginate as the electrolyte coupling with a Na+ preintercalated δ-Na0.65Mn2O4·1.31H2O cathode. The dissociated Na+ in alginate after gelation directly stabilizes the cathodes by preventing the collapse of layered structures during charge processes. The as-fabricated ZIBs deliver a high capacity of 305 mA h g–1 at 0.1 A g–1, 10% higher than the ZIBs with an aqueous electrolyte. Further, the hybrid polymer electrolyte possessed an excellent Coulombic efficiency above 99% and a capacity retention of 96% within 1000 cycles at 2 A g–1. A detailed investigation combining ex situ experiments uncovers the charge storage mechanism and the stability of assembled batteries, confirming the reversible diffusions of both Zn2+ and preintercalated Na+. A flexible device of ZIBs fabricated based on vacuum-assisted resin transfer molding possesses an outstanding performance of 160 mA h g–1 at 1 A g–1, which illustrates their potential for wearable electronics in mass production.
Abstract Medical surgical catheters are widely used in the medical field for drug delivery or postoperative drainage. However, infections associated with local temperature rise often occur at the catheter‐tissue interface, resulting in irreversible pathological damage, cognitive behavioral abnormalities, or even an increased risk of mortality if not monitored in time. Herein, an in situ temperature‐sensing hydrogel coating on the outer surface of medical surgical catheters for real‐time infection monitoring is developed. The hydrogel coating exhibits a record temperature coefficient of resistance of 2.90% °C −1 and maintains stable in vivo. Besides, the hydrogel layer forms a mechanically compatible catheter‐tissue interface and minimizes the risk of inflammatory responses due to its tissue‐like softness (Young's modulus of 4.24 kPa). By applying it in the early detection of infections in the brain of SD rats, the individual survival rate has increased to 90% with timely intervention.
ConspectusImplantable bioelectronics that interface directly with biological tissues have been widely used to alleviate symptoms of chronic diseases, restore lost or degraded body functions, and monitor health conditions in real-time. These devices have revolutionized medicine by providing continuous therapeutic interventions and diagnostics. Energy sources are the most critical components in implantable bioelectronics, as they determine operational lifetime and reliability. Compared with other energy storage and harvesting devices and wireless charging methods, batteries provide high energy density and stable power output, making them the preferred choice for many implantable applications. The advent of implantable bioelectronic devices has been significantly propelled by the high energy densities offered by lithium battery technology, which has led to a profound transformation in our daily lives.To advance the field of implantable bioelectronics, the development of next-generation implantable batteries is essential. These batteries must be soft to match the mechanical properties of biological tissues, minimizing tissue damage and immune responses. Additionally, they must be biocompatible, particularly when in proximity to vital organs like the heart and brain, to prevent toxicity and adverse reactions. Beyond biocompatibility, these batteries need to exhibit excellent electrochemical performance, thermomechanical resilience, and structural integrity for reliable operation in body fluids over extended periods. Enhancing the energy and power density of these batteries can lead to device miniaturization, extend their service life, improve operating efficiency, and meet a broader range of high-power applications. Achieving these advancements not only enables cableless and shape-conformal integration with multifunctionality but also underscores the significant research efforts dedicated to understanding and optimizing the performance of next-generation implantable batteries. To this end, numerous research efforts have been devoted in recent years to developing next-generation implantable batteries from material development, structural design, and performance optimization perspectives.In this Account, we first outline the development history of current implantable batteries from their inception to the present day. We then delineate the requirements for the next generation of implantable batteries, considering emerging application scenarios. Subsequently, we review the recent advancements in the development of soft, biocompatible, long-term stable, high-energy, and high-power-density implantable batteries. Additionally, we explore the efficient integration of these batteries into biomedical devices. We conclude with the development routes and future perspectives for implantable batteries. This Account promotes the development of new implantable batteries through the collaboration of multiple disciplines, including energy, materials, chemistry, biomedical science, and engineering. The emergence of advanced implantable battery technologies is expected to offer countless opportunities to enhance bioelectronics. These advancements will alter the current paradigm of medicine and pave the way for a revolutionary era of human-machine interaction.
A fiber-shaped aqueous lithium ion battery is developed with ultrafast charge–discharge rates and high power density in addition to high energy density.
Abstract Layered manganese oxides adopting pre‐accommodated cations have drawn tremendous interest for the application as cathodes in aqueous zinc‐ion batteries (AZIBs) owing to their open 2D channels for fast ion‐diffusion and mild phase transition upon topochemical (de)intercalation processes. However, it is inevitable to see these “pillar” cations leaching from the hosts owing to the loose interaction with negatively charged Helmholtz planes within the hosts and shearing/bulking effects in 2D structures upon guest species (de)intercalation, which implies a limited modulation to prevent them from rapid performance decay. Herein, a new class of layered manganese oxides, Mg 0.9 Mn 3 O 7 ·2.7H 2 O, is proposed for the first time, aims to achieve a robust cathode for high‐performance AZIBs. The cathode can deliver a high capacity of 312 mAh g −1 at 0.2 A g −1 and exceptional cycling stability with 92% capacity retention after 5 000 cycles at 5 A g −1 . The comprehensive characterizations elucidate its peculiar motif of pined Mg‐□Mn‐Mg dumbbell configuration along with interstratified hydrogen bond responsible for less Mn migration/dissolution and quasi‐zero‐strain characters. The revealed new structure‐function insights can open up an avenue toward the rational design of superstructural cathodes for reversible AZIBs.
Abstract Materials that combine metallic electrical conductivity and high toughness are in great demand for advancing flexible electronics. However, such materials are still lacking. Previously reported flexible materials with metallic conductivity (≥1 × 10 6 S·m ‒1 ) usually compromise on toughness (<3 MJ·m ‒3 ). Here, a binary metalgel is presented that features a binary metal continuum stabilized by a three‐dimensional polymer network. The binary metal continuum consists of hard metal particles encapsulated by soft liquid metal. The continuous conductive pathways within the polymer network enable a metallic electrical conductivity of 2.50 × 10 6 S·m ‒1 . Additionally, the combination of hard metal particles, soft liquid metal, and polymer network facilitates stress transfer throughout the material, creating a triple‐mode energy dissipation mechanism that enhances toughness to 14.40 MJ·m ‒3 . This strategy offers a valuable framework for developing materials that achieve both superior electrical and mechanical properties.
Electrochemical nitric oxide (NO) sensors are capable of real-time monitoring of intracranial NO concentration, which is crucial for understanding the functions of NO in the brain. However, traditional rigid electrochemical sensors used in the brain face the dilemma of low sensitivity and abnormal NO concentrations caused by neuroin-flammatory responses. Here, we report a highly sensitive and accurate electrochemical NO sensor that combines both physical and chemical adsorption capabilities for NO. The physical and chemical adsorption capabilities can be attributed to the high specific surface area and abundant carboxyl functional groups of the electrode, respectively. Besides, it is soft and matches the mechanical property of brain tissue, enabling an adaptable interface. The resulting NO sensor exhibits the highest reported sensitivity of 3245 pA nmol−1 L, with a low detection limit of 0.1 nmol L−1. No significant inflammatory response or excess NO expression is observed after implantation, improving the detection accuracy. The sensor successfully captures NO fluctuations in the brain and enables simultaneous NO detection in multiple brain regions, facilitating research on NO physio-pathological actions in the brain.
Abstract Zinc (Zn) metal is considered the promising anode for “post‐lithium” energy storage due to its high volumetric capacity, low redox potential, abundant reserve, and low cost. However, extravagant Zn is required in present Zn batteries, featuring low Zn utilization rate and device‐scale energy/power densities far below theoretical values. The limited reversibility of Zn metal is attributed to the spontaneous parasitic reactions of Zn with aqueous electrolytes, that is, corrosion with water, passive by‐product formation, and dendrite growth. Here, a new ion‐selective polymer glue coated on Zn anode is designed, isolating the Zn anode from the electrolyte by blocking water diffusion while allowing rapid Zn 2+ ion migration and facilitating uniform electrodeposition. Hence, a record‐high Zn utilization of 90% is realized for 1000 h at high current densities, in sharp contrast to much poorer cyclability (usually < 200 h) at lower Zn utilization (50–85%) reported to date. When matched with the vanadium‐based cathode, the resulting Zn‐ion battery exhibited an ultrahigh device‐scale energy density of 228 Wh kg −1 , comparable to commercial lithium‐ion batteries.
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