Conventional Li-ion batteries use graphite anodes, which have a theoretical specific capacity of 372 mAh/g, which limits their application for high capacity energy storage devices. Silicon has been tried because of its high theoretical specific capacity (on the order of 4200 mAh/g) but the stress created due to volume expansion during intercalation of Li causes fracture and hence electrical isolation between the particles and the current collector leading to capacity loss. This invention demonstrates the design of metallurgical grade polycrystalline silicon anodes which can achieve high reversible capacity, on the order of 1000 mAh/g, with high coulombic efficiency (99.5%) and low cost.
This invention can allow production of high coulombic efficiency on the order of 99.5% while also having specific capacity nearly 3x higher than graphite. It also reduces the volume expansion issues associated with Li intercalation. This allows for development of a higher capacity energy storage device.
Development of higher capacity energy storage devices for use in transportation for longer range; energy storage from renewable resources such as wind and solar.
Si-based Li-ion anode has 1000 mAh/g capacity vs 372 mAh/g for graphite
Si-based Li-ion anode had 99.5% coulombic efficiency
Use of polycrystalline Si allows low cost production