Nio Develops Prototypes of CFRP Battery Enclosures

Leading Chinese automobile manufacturer, Ni collaborated with SGL Carbon to develop prototypes for battery enclosures made of carbon fiber-reinforced plastic (CFRP). The enclosures were developed for Nio’s high-performance electric vehicles (EVs). Nio used CFRP to make battery enclosures which are  safer and more stable and are also extremely lightweight.

It is possible to change the entire battery enclosure, including the batteries, at the company’s swapping stations of NIO within just three minutes. NIO had initially presented the swap concept at NIO Day in December 2017 and used the recent Shanghai Auto Show to demonstrate the actual system along with a number of technological innovations including the CFRP battery enclosure.

Sebastian Grasser, head of market segment Automotive in the Composites – Fibers & Materials business unit at SGL Carbon said that generally battery enclosures for electric vehicles are made chiefly of aluminum and steel. When compared to such enclosures, the CFRP battery enclosure is about 40 percent lighter. Some of its other benefits include greater stiffness and thermal conductivity that is about  200 times lower than that of conventional enclosures, thus giving the battery better protection from heat and cold. The CFRP composite also offers excellent values in terms of water and gas leakage tightness and corrosion resistance.

Bin Wei, Senior Manager of Lightweight Engineering at NIO said that lightweight technology is one of the core elements in NIO technology roadmap. Through the use of composite materials like high-performance carbon fiber in battery enclosure systems, it is easy for Nio models to achieve better dynamic performance, longer range, and obtain remarkably high energy density of the battery pack (over 180 Wh/kg). These features align well with the core values of NIO brands of ultimate product and system efficiency.

The characteristics of the battery enclosure are mainly derived from the bottom and cover plate design, involving the use of a sandwich core with multiple layers of carbon fiber non-crimped fabrics. SGL’s own Lightweight and Application Center developed the tool to produce the bottom and cover plate. Along the fully integrated value chain, carbon fiber is produced for these components at the SGL plants in Moses Lake and Muir of Ord, and processed into non-crimped fabrics in Wackersdorf. Besides producing the bottom and cover plate, the SGL site in Ried, Austria, also assembled the individual components.

It is expected that greater demand for electric vehicles in the future will boost the demand for lightweight solutions for battery enclosures in the automotive sector. SGL Carbon is already working with various partners to continue developing different battery enclosures made of composites with the aim of scaling them for electric vehicle batteries of all sizes and designs.