Gm Global Technolgoy Operations, Inc.

Ramakrishnan Narayanrao

Sampath K Vanimisetti

Mark William Verbrugge

The gravimetric and volumetric efficiency of lithium ion batteries may be increased if higher capacity materials like tin and silicon are substituted for carbon as the lithium-accepting host in the negative electrode of the battery. But both tin and silicon, when fully charged with lithium, undergo expansions of up to 300% and generate appreciable internal stresses. These internal stresses, which will develop on each discharge-charge cycle, may lead to a progressive reduction in battery capacity, also known as battery fade. The effects of the internal stresses may be significantly reduced by partially embedding tin or silicon nanowires in the current collector. Additional benefit may be obtained if a 5 to 50% portion of the nanowire length at its embedded end are coated or masked with a composition which impedes lithium diffusion. Methods for embedding and masking the nanowires are described.

Fade-resistant high capacity electrodes for a lithium-ion battery

Methods for decreasing mechanical degradation in a lithium battery are provided. At least a portion of one of the anode or the cathode includes a plurality of biconcave particles. The biconcave particles provide increased surface area for lithium diffusion without increasing the volume of the particles. As the lithium diffuses across the particles, the combination of convergent and divergent diffusion fronts of lithium reduces the stresses and elastic strain energy responsible for mechanical degradation of the electrode while increasing the rate of lithium intake.

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Karnataka, India

Ramakrishnan Narayanrao