• silicon;
  • anodes;
  • graphene;
  • cathodes;
  • lithium ion batteries;
  • energy storage

High capacity electrodes based on a Si composite anode and a layered composite oxide cathode, Ni-rich Li[Ni0.75Co0.1Mn0.15]O2, are evaluated and combined to fabricate a high energy lithium ion battery. The Si composite anode, Si/C-IWGS (internally wired with graphene sheets), is prepared by a scalable sol–gel process. The Si/C-IWGS anode delivers a high capacity of >800 mAh g−1 with an excellent cycling stability of up to 200 cycles, mainly due to the small amount of graphene (∼6 wt%). The cathode (Li[Ni0.75Co0.1Mn0.15]O2) is structurally optimized (Ni-rich core and a Ni-depleted shell with a continuous concentration gradient between the core and shell, i.e., a full concentration gradient, FCG, cathode) so as to deliver a high capacity (>200 mAh g−1) with excellent stability at high voltage (∼4.3 V). A novel lithium ion battery system based on the Si/C-IWGS anode and FCG cathode successfully demonstrates a high energy density (240 Wh kg−1 at least) as well as an unprecedented excellent cycling stability of up to 750 cycles between 2.7 and 4.2 V at 1C. As a result, the novel battery system is an attractive candidate for energy storage applications demanding a high energy density and long cycle life.