Morphological control of LiNi0.8Mn0.1Co0.1O2 cathodes for lithium-ion cells using biotemplating

The novel biotemplating method was used to synthesise NMC811 such that particle morphology would be manipulated, performance of the cathode increased, and lithium-ion cells improved to help reach the goal of net-zero. NMC811, defined by a high specific capacity of >200 mAh/g but a poor capacity retention and structural stability, was synthesised using either dextran or sodium alginate, preheated at 300 °C for 2h and calcined at 800 °C using nitrate precursors or 850 °C using acetate precursors for 2 h under O2. The resulting layered, organised NMC811 indicated high layering and low mixing of Li+ and Ni2+ cations with nanoscale octahedral and rounded primary particles of average diameter 600 to 1000 nm. When cycled to 4.2 V at 0.1 C resulted in specific capacities as high as 240 mAh/g with capacity fade of 30 mAh/g over 50 cycles when using sodium alginate or 150 mAh/g specific capacity with a capacity fade of 10 mAh/g over 50 cycles when using dextran. Plate and nanowire novel morphologies were also observed when using dextran and sodium alginate respectively. Sodium alginate and κ-carrageenan were also used to dope NMC811 with sodium and sulfur respectively. 10% Na-doped and 0.5% S-doped NMC811 were viable, exhibiting layered, organised NMC811 structures with sodium peroxide/sodium carbonate and lithium sulfate secondary phases respectively, and exhibiting morphological control of nanoscale, octahedral primary particles. Novel microwire morphologies were also observed when biotemplated with κ-carrageenan. When cycled to 4.2 V at 0.1 C, specific capacities of 170 mAh/g and 150 mAh/g with capacity fade of 10 mAh/g and 40 mAh/g after 50 cycles were observed when doping with sodium alginate and κ-carrageenan, respectively. Using the novel biotemplating method, nanoscale novel morphologies can be synthesised and NMC811 specific capacity and capacity retention increased, while cathode synthesis is more inexpensive and quicker.