RE:credibilityPart of Zentek's news today: (a learning point)
Further to Zentek's press releases dated November 22, 2018 and February 18, 2022, Zentek has been collaborating with Dr. Michael Pope at the University of Waterloo for the last three years, developing battery technology to improve anode performance.
One highly studied area for lithium-ion battery (LIB) development is to improve the anode material. Currently electric vehicle anodes are composed of graphite, which has a limited theoretical specific capacity of ~372 mAhg-1. Silicon (Si) has attracted significant attention as a replacement material, mainly due to its high specific capacity of 4,200 mAhg-1, but also due to its low working potential, low price and the availability of silicon. However, the industrialization of silicon anodes is hindered by an important engineering roadblock: silicon has an enormous volumetric fluctuation (greater than 300% in all dimensions) when charging and discharging. This feature is the root cause behind three major issues:
- Poor cycle lifetime due to self-pulverization of the anode.
- Irreversible capacity loss and low coulombic efficiency.
- Destruction and reformation of the solid-electrolyte interface, which consumes electrolyte and causes thickening and poor ionic mobility.
Using silicon in the anode material, Dr. Pope has addressed these issues, and has created a patent-pending graphene wrapped silicon anode material.
Key characteristics of graphene-wrapped silicon anode, as announced in February 2022 include:
- At practical mass loading of 2.5mg/cm2, the electrode achieved 2.04 mAh/cm2 and retained 79% of this capacity after 200 cycles against a lithium half-cell.
- When paired with a commercial lithium iron phosphate cathode, the fully assembled battery retained 93.3% of its initial capacity over 100 cycles.
- Works with current lithium-ion batteries as a replacement for graphite1.
Since April, Dr. Pope's team has optimized the anode material, which now has a specific capacity of over 1,000 mAh/g and retains over 80% of its capacity over 320 charge-discharge cycles. The specific capacity of this material is a significant improvement over common graphite anodes; however, the cycle life still requires improvement compared to typical electric vehicle batteries, which lose about 4% capacity over 1,000 charge-discharge cycles. Zentek and Dr. Pope's team will continue to develop this technology with the goal of improving performance to meet industry requirements. Newly optimized chemistries are reaching specific capacities as high as 1,500 mAh/g, an over 400% improvement over graphite anodes. This significant improvement in energy density is complemented by impressive cycle stability. These performance tests were done under accelerated protocols and will need to be confirmed in standard tests.
Zentek filed a patent application under the Patent Cooperation Treaty on May17th, 2022.