Magnetically Aligned Low Tortuosity Electrodes

Applications

This technology can be applied to Lithium-ion cells used in electric vehicles to increase ion transport while maintaining energy density.

Problem Addressed

By simply doubling the electrode thickness, the cost of a plug-in hybrid electric vehicle (PHEV) pack could be reduced by ~$600. However, only making the electrodes thicker allows only a fraction of the stored energy to be delivered at high rates because of decreased ion transport through liquid electrolyte filled pores. Increasing the porosity increases ion transport but simultaneously diminishes the battery’s energy density. However, the proposed technology decreases the tortuosity, a measure of the effectiveness of the pore structure in respect to mass transport, which enables a high rate of capability while maintaining the energy density.

Technology

This invention creates low tortuous structures through anisotropic pores, which are oriented in the direction of ion transfer. This process creates anisotropic pores by aligning anisotropic para- or ferro- magnetic fugitive pore formers or chaining of fugitive magnetic particles in the electrode matrix. The fugitive particles are dispersed in a slurry of electrode powder and other additives. A magnetic field is applied to the mixture. The fugitive particles align with the field and then can be slowly removed or the structure can be consolidated in another fashion (e.g. polymerization, gelation). Alternatively, non-magnetic electrode particles are magnetically induced in a magnetic fluid. The electrode particles align and the magnetic fluid is evaporated forming a chained structure from the electrode particles. If two different sizes of non-magnetic particles are used at high applied magnetic fields, macro and micro porous channels form in the resulting electrode. Either method creates anisotropic pores aligned with ion transfer to enable a high rate of capability while maintaining energy density, and can be used at larger scales to reduce the cost of battery production. 

Advantages

  • Can reduce battery production cost
  • Increases rate of capability and maintains energy density