Hui Li,Feng Wang,Chongrong Zhang,Weixiao Ji,Jiangfeng Qian,Yuliang Cao,Hanxi Yang,Xinping Ai
The thermal runaway is now recognized to be a main cause for the unsafety of Li-ion batteries, which poses a serious concern for large scale electric vehicles and energy storage applications . To address this issue, we propose in this work a new positive-temperature-coefficient (PTC) material, poly(3-Octylpyrrole):poly(styrenesulfonate) (P3OPy:PSS)/carbon composite, and use it as conductive matrix of cathode to enhance thermal stability of Li-ion batteries. The electrochemical and safety evaluations reveal that the such-fabricated graphite/LiCoO 2 full pouch cells exhibit not only improved electrochemical performances compared to the conventional cells at ambient temperature conditions, but also a reliable thermal-switching function at an elevated temperature of ≥ 120 °C, demonstrating a strong tolerance to overcharge, thermal impact and short-circuiting. Such a thermal stable mechanism originates from the PTC effect of the cathode matrix , which turns the conductive network into an insulating state under thermally abusive conditions and therefore terminates the charge/discharge reactions, thus protecting the cell from thermal runaway. This work provides a new strategy and electrode design for constructing safer LIBs. In addition, the materials and fabrication technique of the thermal stable cathode is facile and also fully compatible with the present industrial manufacture process, making it convenient for use in practical LIBs.
Silicon (Si) is a promising anode material for lithium-ion batteries (LIBs) owing to its very high lithium storage capacity; however, fragmentation of Si caused by drastic volume change during lithium insertion and extraction leads to serious capacity decay during cycling. In this work, we report a novel method to synthesize an in situ nanocomposite containing Si nanoparticles evenly embedded in an electrically conductive SiOx@C network (Si/SiOx@C) from one single polysiloxane precursor. In our process, Si nanocrystals were reduced from the polysiloxane precursor using a low temperature molten salt reduction method, and carbon segregated out in the SiOx@C phase which evolved during the subsequent pyrolysis. As an anode material for LIBs, the Si/SiOx@C nanocomposite showed a specific capacity up to 1292 mA h g−1 at a current density of 0.4 A g−1 and 81.84% capacity retention after 200 cycles. The high capacity and stable performance of Si/SiOx@C as an anode material can be attributed to the continuous SiOx@C matrix which provides reliable mechanical support, electronic and ionic conductivity, and a stable solid–electrolyte interphase (SEI). This work demonstrated the viability of deriving a homogenous nanocomposite from a single polymeric precursor, which creates a promising anode material for next-generation LIBs.
Nitrite plays a critical role in a variety of physiological processes and maintaining the nitrite level in an appropriate range is vital to keep healthy. Current nitrite analysis methods lack sensitivity and require tedious operations, which could not meet the need of point-of-care (POC) nitrite detection in precision medicine. Here we present a cyanocobalamin (VB12) bionic enzyme-assisted ion-selective amperometric biosensor based on 3D porous conductive matrix (PCM), which can facilitate rapid and accurate POC nitrite monitoring in complex biofluids. The experimental findings quantitatively demonstrate that the biosensor has a sensitivity of 64.08 μA/(mM·cm2), a wide linear range of 0.025–45 mM, and low limit of detection of 1 nM. Moreover, the developed VB12/BSA-PCM biosensor shows outstanding stability after 21 days with 2% decline in current signal, and high repeatability between batches with RSD of only 1.29%. Real salivary nitrite detection has been evaluated, and the results match well with the commercial nitrite analyzer. Thus, the bionic enzyme-assisted ion-selective amperometric biosensor proposed herein has potential utility as an affordable tool for POC detection and home-based healthcare.
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