Researchers have designed a unique lithium ion battery (LIB) electrode, where red phosphorus is stuffed into carbon nanotubes (CNTs). They revealed reversible electrochemical reactions and relatively high structural stability of red phosphorus in the nanotubes even after the fiftieth charge-discharge cycle. The charge-discharge capacities are twice or even higher than that of graphite in commercial LIBs. Therefore, a new electrode material for LIBs with high capacity is proposed.