Scientists turn waste paper into battery parts for smartphones and electric vehicles

Scientists turn waste paper into battery parts for smartphones and electric vehicles

Scientists at Nanyang Technological University Singapore (NTU Singapore) have developed a technique to convert waste paper, disposable packaging and cardboard bags and boxes into a crucial component of lithium-ion batteries.

Through a process called carbonization that converts paper into pure carbon, NTU researchers have turned paper fibers into electrodes, which can be made into rechargeable batteries that power cell phones, medical equipment and electric vehicles.

To carbonize the paper, the team exposed the paper to high temperatures, which reduces it to pure carbon, water vapor and oils that can be used as biofuel. Because carbonization occurs in the absence of oxygen, it emits negligible amounts of carbon dioxide and the process is a greener alternative to disposing of kraft paper by incineration, producing large amounts of greenhouse gases.

The carbon anodes produced by the research team also demonstrated superior durability, flexibility and electrochemical properties. Lab tests have shown that the anodes can be charged and discharged up to 1,200 times, which is at least double the life of current phone battery anodes. Batteries using NTU-made anodes could also withstand greater physical stress than their counterparts, absorbing crush energy up to five times better.

The method developed by NTU also uses energy-intensive processes and heavy metals compared to current industrial methods of manufacturing battery anodes. Since the anode accounts for 10-15% of the total cost of a Li-ion battery[1]the latter method, which uses low-cost waste, should also reduce the cost of production.

The results have been published in the peer-reviewed scientific journal Additive manufacturing in October.

Using waste paper as a raw material to make battery anodes would also reduce our reliance on conventional sources of carbon, such as carbonaceous fillers and carbon-producing binders, which are mined and then treated with aggressive chemicals and machines.

Paper waste, which includes discarded paper bags, cardboard, newspapers and other paper packaging, accounted for nearly one-fifth of waste generated in Singapore in 2020[2].

Even kraft paper bags, which make up the majority of Singapore’s paper waste, have a large environmental footprint compared to their cotton and plastic counterparts, due to their greater contribution to global warming when incinerated and the potential for ecotoxicity in production. them, a separate NTU 2020 study[3] to found.

The current innovation that offers the opportunity to recycle waste and reduce our dependence on fossil fuels, accelerating our transition to a circular economy, green materials and clean energy, reflects NTU’s commitment to mitigate our impact on environment, which is one of the four great challenges of humanity that the University seeks to address through its NTU 2025 strategic plan.

Assistant professor Lai Changquan of NTU’s School of Mechanical and Aerospace Engineering, who led the project, said: ‘Paper is used in many aspects of our daily lives, from gift wrapping to arts and crafts, to a myriad industrial uses, such as as heavy packaging, protective packaging, void filling in construction… However, little is done to deal with it during its disposal, apart from incineration, which generates high levels of carbon emissions due to their composition paper another lease of life, channeling it into the growing need for devices such as electric vehicles and smartphones, would not only help reduce carbon emissions, but also reduce reliance on mining and heavy industrial methods.

The research team has filed a patent with NTUitive, NTU’s enterprise and innovation company. They are also working on commercializing their invention.

The recipe for greener drum parts

To produce the carbon anodes, NTU researchers joined and laser-cut several thin sheets of kraft paper to form different lattice geometries, some resembling a pointed piñata. The paper was then heated to 1200°C in an oxygen-free oven, to transform it into carbon, forming the anodes.

The NTU team attributes the anode’s superior durability, flexibility and electrochemical properties to the arrangement of the paper fibers. They said the combination of strength and mechanical toughness exhibited by NTU-manufactured anodes would allow batteries in phones, laptops and cars to better withstand the shocks of drops and collisions.

Current lithium battery technology relies on internal carbon electrodes that gradually crack and fall apart after the physical shocks of a fall, which is one of the main reasons battery life decreases over time.

The researchers say their anodes, which are stronger than the current electrodes used in batteries, would help solve this problem and extend battery life across a range of uses, from electronics to electric vehicles.

Study co-author, Dr. Lim Guo Yao, a research engineer at NTU’s School of Mechanical and Aerospace Engineering, said, “Our anodes have a combination of strengths, such as durability, shock absorption, electrical conductivity, that are not found in current. These structural and functional properties demonstrate that our kraft paper-based anodes are a sustainable and scalable alternative to current carbon materials and would find economic value in demanding, high-end, multifunctional applications, such as the nascent field of structural batteries. . “

Assistant professor Lai added: ‘Our method converts a common and ubiquitous material – paper – into another that is extremely durable and in high demand. We hope our anodes meet the growing global need for a sustainable and more environmentally friendly material for batteries. , whose production and poor waste management have a negative impact on our environment”.

Underlining the importance of the work done by the NTU research group, Professor Juan Hinestroza from the Department of Human Centered Design at Cornell University, USA, who was not involved in the research, said: ‘Because kraft paper is produced in large quantities and organized equally across the world, I believe the creative approach pioneered by NTU Singapore researchers has great potential for global impact Any discovery that will enable waste to be used as a raw material for high-value products such as electrodes and foams is indeed a great contribution. I believe this work can break new ground and motivate other researchers to find ways of transforming other cellulose-based substrates, such as textiles and packaging materials, which are discarded in large quantities all over the world. the world”.

The NTU team will conduct further research to improve the energy storage capacity of their material and minimize the thermal energy required to convert paper to carbon.

Remarks:

[1] Search for Lux. Li-ion Battery Innovation Roadmap (2019).

[2] National Environment Agency of Singapore. Reduction of overall waste generation in 2020, with less waste sent to Semakau landfill (2021).

[3] Nanyang University of Technology. NTU Singapore scientists report that plastic bags may be ‘more environmentally friendly’ than paper and cotton bags in cities like Singapore (2020).

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