Mason Graphite Inc (TSX-V:LLG, OTCQX:MGPHF). has announced "highly promising" results from trials using its Lac Guéret spherical purified graphite (SPG) with silicon (Si) additions.
The company said the work program was conducted by Sicona Battery Technologies (Sicona), one of Mason Graphite’s strategic partners, using its patent-pending process of combining Si nanoparticles, carbon, SPG, and/or synthetic graphite in producing a cost-effective, high-performance next-generation lithium-ion battery anode material.
Si increases the energy density of lithium-ion batteries, allowing more electrical energy storage per unit of anode volume -- translating into a longer range for electric vehicles while using a battery similar in size. Silicon effectively displays a much higher capacity to store lithium (Li) ions, and thus energy, compared to graphite, but inevitably swells during charging, leading to important mechanical challenges.
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The solution currently pursued by the industry involves small additions of Si (typically in the form of silicon-oxide “SiOx”) to graphite-based anode materials upon making the electrode slurries which increases the energy density while limiting the swelling to manageable levels.
However, Mason Graphite said that this approach is limited by the high cost of SiOx materials as well as the practical increases in energy density, long-term cycling, and rate capability.
The company said the objective for the first commercial product, established through discussions by Sicona with several potential customers worldwide, is a composite anode material having an initial capacity of 450 milliamperes-hour per gram of material (mAh/g). This commercial grade is expected to be rapidly adopted, as it can be easily implemented in existing battery manufacturing processes.
The latest series of tests was based on Sicona’s proprietary formulation to produce an engineered silicon-graphite-carbon active anode material which includes a few percent of Si, carbon, and a blend of Mason Graphite’s SPG and synthetic graphite. The composite anode material was then tested in prototype Li-ion batteries (half coin-cells) by Sicona in an 80:10:10 formulation.
Some of the highlights include
- 435 mAh/g capacity, an increase of 19% compared to a typical capacity of 365 mAh/g for natural graphite and 22.5% increase above a typical capacity of 355 mAh/g for synthetic graphite;
- The 450 mAh/g commercial objective is expected to be easily achieved by Sicona with Mason Graphite’s SPG through formulation optimization of some key parameters in upcoming tests;
Mason Graphite noted that cycling tests, which include rate variation tests, are still continuing on the same cells and optimization tests will be conducted shortly. Tests to achieve higher capacities (such as 550 mAh/g and 650 mAh/g) and full pouch cell testing are also planned in the near future.
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