• Analysis of the Vittangi graphite indicates particle structure of the order desired (10- 20μm), yielding significant cost savings in the processing of battery anode material. The excellent liberation from the host silica gangue and homogeneous graphite size distribution generates high process yields >85%, giving Talga Resources a major processing advantage against competitors (common yield ~50%).
• The purified, coated and functionalised active Talnode®-C powder has generated significant commercial qualifications against current industry-leading commercial benchmark cells.
• Talnode®-C is currently undergoing full-cell qualification with a range of new technical and commercial partners and independent battery institutes in Asia, USA and Europe as it progresses through the validation processes.
Industry leading results • Breakthrough test results of the engineered active Li-ion anode product at the leading global independent facility Warwick Manufacturing Group (“WMG”), part of the University of Warwick’s Energy Innovation Centre, indicate significant performance enhancements of Talnode®-C against commercial benchmarks.
• Announced in May 2018, a range of Li-ion battery pouch cells were fabricated using Talga’s graphite anode and commercial nickel-manganese-cobalt (“NMC”) cathodes, utilising standard industrial roll to roll processing conditions to prepare large format (A5) cells.
• Following industry procedures, active material slurries with optimised rheology (flow properties) coat anode and cathode electrodes on copper and aluminium rolls respectively. The coated electrodes are then calendered (finishing process to smooth coating) to attain higher electrode densities and required porosities.
• Electrodes are subsequently cut to the required size and stacked with a separator sandwiched between the electrodes to form the A5 pouch cell, which is finally filled with standard lithium salt electrolyte (LiPF6) dissolved in a carbonate solvent.
• The reference commercial anode cell was prepared under the same conditions, with identical weight inside the cells and paired with the same type of NMC cathode.
Preparation of Talnode®-C active anode material for commercial testing
• Relative measurements of the pouch cell performance at WMG indicates significant enhancements for Talga anodes: o Higher capacity – 20% higher capacity is observed for identical active material content at 0.5C and 2C rates respectively for cells with Talga anodes, with the first cycle loss in the full cell lower at 6%. Talga full capacity at 0.5C (left) and 2C (right) achieving 100% capacity retention at 5.63Ah and 4.57Ah respectively
o Voltage charging profiles at the higher 2C rate also have enhanced performance using Talga anodes compared to reference graphite, retaining more than 99% of the initial capacity under accelerated tests to 300 cycles. Cycle stability is indicative of normal life greater than 4,000 cycles. Battery capacity characteristics to available specification data from global leading electric vehicle and power tool battery makers over 300 cycles, normalised to the same start discharge capacity
Endurance test • An engagement with IV Electrics (formerly Italian Volt) subjected benchtop tests designed to replicate extreme real world conditions of the “Stelvio” Italian Alpine mountain road to simulate high performance of the “Lacama” motorcycle battery pack.
• The cyclic test pressures the ability of a battery to efficiently collect fast charge regenerative current (from braking) following high-power discharge (acceleration) in low temperature conditions.
• Results focusing on the running time relate to battery cell performance before limits in voltage drop or cell temperature forced the end of the test.
Stelvio test – time (seconds) for cell voltage to fall below 3.2V at 14°C [Details – 3 second discharge at 3C, charge 1 second at 1C, rest 4 seconds and repeat] • Results indicate that Talnode®-C cells outperform the endurance of market leading commercial cells by up to 36%, also confirming the fast charge, high power and low temperature properties in real-world applications.
• Practically, Talnode®-C will require less thermal management and materials, reducing cost and weight, while increasing the energy density (range) and safety of battery packs.
Extreme temperatures • More recently, tests conducted at a leading Japanese battery institute examined performance under a range of temperatures including freezing conditions.
• Talnode®-C anode material supported retention of 100% capacity and 100% cycle efficiency at freezing conditions (0°C) to out-perform market leading commercial anode products. Comparison of capacity retention between graphite anode market leader and Talnode®-C at 25°C after 30 charge-discharge cycles and at 0°C after 60 charge-discharge cycles
• Freezing conditions typically inhibit normal battery performance, forcing lower capacity retention and cycling efficiency, creating shorter runtimes for devices or shorter vehicle range. Under reduced temperature conditions, lithium plating occurs – the coating of electrode surfaces due to lithium ions reducing to a metallic phase.
• Practically speaking, the range of electric vehicles has been measurably impacted, falling up to 41% in cooler northern hemisphere countries (source: American Automobile Association).
• More significantly, cold temperatures can also cause dendritic deposits of lithium metal which perforate the protective separator, creating internal short circuiting or fire in the cell.
• A spate of electrical system failures across the Boeing 787 Dreamliner range in 2013 was traced back to cold winter overnight temperatures fostering lithium plating within the battery cells resulting in short circuits (source: All Nippon Airways).
• Cumulatively, validation indicates outstanding Talnode®-C performance against benchmark iterations.
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