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These are how the nano-wires appear after the battery has gone through 10 charge-discharge cycles.
A battery company supported by the Vehicle Technologies Office (VTO) has an agreement to manufacture silicon nanowire material for lithium-ion batteries on a commercial scale for the first time. OneD Materials, which had a project from 2011 to 2014 with VTO, recently signed a production license and agreement with EaglePicher Technologies, a U.S. company that manufactures battery cells and batteries. EaglePicher is setting up a new facility in Joplin, MO to manufacture OneD’s SiNANOde material as part of its efforts to increase lithium-ion battery cell production. Using this technology, EaglePicher can increase the performance of their cells and batteries for niche market applications.
Silicon offers a number of advantages over pure graphite, the current material of choice for lithium ion batteries. In particular, silicon’s energy storage capacity is more than 10 times higher than graphite. However, replacing graphite with silicon is currently not practical because silicon expands and contracts more than 300% during battery cycling.
To take advantage of silicon’s benefits while minimizing its changes in volume, OneD Materials has designed several composites that combine silicon nanowires (wires that are one billionth of a meter thick) and graphite. For example, one of OneD’s materials is 18% silicon nanowire by weight and has nearly three times as much capacity as the graphite-only material. By integrating OneD’s silicon nanowire anode into full battery cells, EaglePicher has been able to demonstrate cell energy densities around 300 Wh/kg, a significant improvement over prior technologies. By increasing the amount of energy a battery cell can store, increased energy density can either allow manufacturers to increase the all-electric range of a plug-in electric vehicle with the same volume of batteries or use fewer batteries to achieve the same range, potentially lowering the vehicle’s cost.
OneD Materials’ process is particularly unique because they can grow silicon nanowires within the graphite material in a single step. Because the majority of the material is still graphite, manufacturers can continue using the same process they do now to coat the negative electrodes in lithium ion batteries, lowering manufacturing costs.
EaglePicher is also licensing a scalable manufacturing process from OneD as well as vertically integrating the production of the novel anode material into their new factory.
The VTO-supported project with OneD helped them integrate the SiNANOde material into a battery cell, test its performance, and scale-up manufacturing. For more information on this project, see OneD’s presentation at VTO’s 2014 Annual Merit Review and Peer Evaluation.
The Vehicle Technologies Office (VTO) develops and deploys efficient and environmentally friendly highway transportation technologies that will enable America to use less petroleum. These technologies will provide Americans with greater freedom of mobility and energy security, while lowering costs and reducing environmental impacts.
The Office of Energy Efficiency and Renewable Energy (EERE) success stories highlight the positive impact of its work with businesses, industry partners, universities, research labs, and other entities.