mobile | classic  
Dataweek Electronics & Communications Technology Magazine





Follow us on:
Follow us on Facebook Share via Twitter Share via LinkedIn


Search...

Electronics Buyers' Guide

Electronics Manufacturing & Production Handbook 2017


 

Battery tech shrugs off thermal cycling
24 February 2016, Power Electronics / Power Management

Researchers at Stanford University have developed the first lithium-ion battery that shuts down before overheating, then restarts immediately when the temperature cools.

The new technology could prevent the kind of fires that have prompted recalls and bans on a wide range of battery-powered devices, from recliners and computers to navigation systems and hoverboards.

“People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries,” said Zhenan Bao, a professor of chemical engineering at Stanford. “We’ve designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance.” Bao and her colleagues describe the new battery in a study published in the 11 January issue of the journal Nature Energy.

A typical lithium-ion battery consists of two electrodes and a liquid or gel electrolyte that carries charged particles between them. Puncturing, shorting or overcharging the battery generates heat. If the temperature reaches about 150°C, the electrolyte could catch fire and trigger an explosion.

Several techniques have been used to prevent battery fires, such as adding flame retardants to the electrolyte. In 2014, Stanford engineer Yi Cui created a smart battery that provides ample warning before it gets too hot. “Unfortunately, these techniques are irreversible, so the battery is no longer functional after it overheats,” said study co-author Cui, an associate professor of materials science and engineering and of photon science. “Clearly, in spite of the many efforts made thus far, battery safety remains an important concern and requires a new approach.”

Nanospikes

To address the problem, Cui, Bao and post-doctoral scholar Zheng Chen turned to nanotechnology. Bao recently invented a wearable sensor to monitor human body temperature. The sensor is made of a plastic material embedded with tiny particles of nickel with nanoscale spikes protruding from their surface. For the battery experiment, the researchers coated the spiky nickel particles with graphene, an atom-thick layer of carbon, and embedded the particles in a thin film of elastic polyethylene.

“We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it,” said Chen, lead author of the study. “To conduct electricity, the spiky particles have to physically touch one another. But during thermal expansion, polyethylene stretches. That causes the particles to spread apart, making the film non-conductive so that electricity can no longer flow through the battery.”

When the researchers heated the battery above 70°C, the polyethylene film quickly expanded like a balloon, causing the spiky particles to separate and the battery to shut down. But when the temperature dropped back down to the same temperature, the polyethylene shrank, the particles came back into contact, and the battery started generating electricity again.

“We can even tune the temperature higher or lower depending on how many particles we put in or what type of polymer materials we choose,” said Bao, who is also a professor, by courtesy, of chemistry and of materials science and engineering. “For example, we might want the battery to shut down at 50°C or 100°C.”

Reversible strategy

To test the stability of the new material, the researchers repeatedly applied heat to the battery with a hot-air gun. Each time, the battery shut down when it got too hot and quickly resumed operating when the temperature cooled. “Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety,” Cui said. “This strategy holds great promise for practical battery applications.”


  Follow us on Facebook Share via Twitter Share via LinkedIn    

Further reading:

  • Automotive buck regulator
    19 April 2017, KH Distributors, Power Electronics / Power Management
    Exar’s XR76203-Q is a synchronous step-down regulator combining the controller, drivers, bootstrap diode and MOSFETs in a single package for point-of-load supplies well suited for automotive applications. ...
  • 9 W DC-DC converters
    19 April 2017, Vepac Electronics, Power Electronics / Power Management
    New from XP Power is the ITZ series of compact regulated 9 Watt DC-DC converters, believed to be the industry’s smallest of its kind. The units accommodate an ultra-wide 4:1 input and are available with ...
  • Semiconductor switches as replacements for relays and fuses
    22 March 2017, Infineon Technologies, Power Electronics / Power Management
    Infineon (Siemens Semiconductors at the time) launched the first PROFETs (PROtected mosFETs) on to the market about 25 years ago. This meant there was finally an alternative to relays and fuses in many ...
  • Digital power controllers
    22 March 2017, Avnet South Africa, Power Electronics / Power Management
    Microchip announces the new dsPIC-33EP128GS808 family of high-performance, live-updateable dsPIC digital signal controllers (DSCs). The new devices offer up to 128 KB of dual-partition Flash memory with ...
  • Step-down power modules
    22 March 2017, EBV Electrolink, Power Electronics / Power Management
    Texas Instruments introduced a pair of 12 V, 10 A, 4 MHz step-down power modules that require just one external voltage-setting resistor for a complete solution. The easy-to-use SWIFT TPSM84A21 and TPSM84A22 ...
  • DAC for 4-20 mA loops
    22 March 2017, EBV Electrolink, Power Electronics / Power Management
    Texas Instruments introduced a digital-to-analog converter (DAC) that combines industry-leading precision performance with simpler power supply design. The 16-bit DAC8775 operates from a single, wide ...
  • Tiny step-down converter
    22 March 2017, NuVision Electronics, Power Electronics / Power Management
    The MPM3804 from Monilithic Power Systems is a monolithic, step-down, switch-mode converter with built-in, internal power MOSFETs and an inductor. It achieves 0,6 A of continuous output current from a ...
  • A good battery pack is not a case of plug and pray
    22 February 2017, Uniross Batteries, Power Electronics / Power Management
    Uniross’s Michael Rogers explores some of the issues behind producing battery packs, and how the difference between a good one and a bad one is more than skin deep.
  • Improving power system dependability through battery surveillance and management
    22 February 2017, Comtest, Test & Measurement, Power Electronics / Power Management
    The installation of uninterruptible power ­supplies (UPS) or other backup power systems are typically a forgotten piece of insurance for maintenance, facility or operations managers to ensure operational ...
  • 700 V power MOSFETs
    22 February 2017, Arrow Altech Distribution (AAD), Power Electronics / Power Management
    Infineon Technologies developed the new 700 V CoolMOS P7 family to serve today’s and tomorrow’s trends in quasi resonant flyback topologies. These new MOSFETs offer performance improvements compared ...
  • Load switch with programmable current limit
    22 February 2017, NuVision Electronics, Power Electronics / Power Management
    The MPQ5073 from Monolithic Power Systems is a load switch to provide 2 A load protection covering a 0,5 V to 5,5 V voltage range.    Featuring low RDS(ON) in a QFN-12 (2 x 2 mm) package, it represents ...
  • DIN-rail power supplies
    22 February 2017, Brabek, Power Electronics / Power Management
    The REDIN240 range of DIN-rail mounted power supplies from Recom have an ultra slim (only 46 mm) robust case, 4 mm screw terminal connectors and use high-reliability components. These 240 W units can ...

 
 
         
Contact:
Technews Publishing (Pty) Ltd
1st Floor, Stabilitas House
265 Kent Ave, Randburg, 2194
South Africa
Publications by Technews
Dataweek Electronics & Communications Technology
Electronic Buyers Guide (EBG)

Hi-Tech Security Solutions
Hi-Tech Security Business Directory

Motion Control in Southern Africa
Motion Control Buyers’ Guide (MCBG)

South African Instrumentation & Control
South African Instrumentation & Control Buyers’ Guide (IBG)
Other
Terms & conditions of use, including privacy policy
PAIA Manual





 

         
    Classic | Mobile

Copyright © Technews Publishing (Pty) Ltd. All rights reserved.