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.

High-energy-density rechargeable batteries are needed to fulfill various demands such as self-monitoring analysis and reporting technology (SMART) devices, energy storage systems, and (hybrid) electric vehicles. As a result, high-energy electrode materials enabling a long cycle life and reliable safety need to be developed. To ensure these requirements, new material chemistries can be derived from combinations of at least two compounds in a secondary particle with varying chemical composition and primary particle morphologies having a core-shell structure and spherical cathode-active materials, specifically a nanoparticle core and shell, nanoparticle core and nanorod shell, and nanorod core and shell. To this end, several layer core-shell cathode materials were developed to ensure high capacity, reliability, and safety.

Core−shell, nickel-rich layered oxide materials with a full concentration gradient (FCG) core and thin shells with low nickel content have been investigated. Hierarchically structured core−shell materials have the same FCG core, where the composition gradually changes from Li-[Ni 0.86 Co 0.07 Mn 0.07 ]O 2 to Li[Ni 0.67 Co 0.09 Mn 0.24 ]O 2 from the center to the outer surface. A thin shell composed of either Li[Ni 0.48 Co 0.26 Mn 0.26 ]O 2 or Li[Ni 0.56 Co 0.18 Mn 0.26 ]O 2 was applied to the outer surface of the FCG core. This hierarchical core−shell structure efficiently integrates the benefit of high energy from the Ni-rich core, structural stability and favorable transport of Li + ions from the FCG core, and surface stability from the low-Ni and high-Mn shell. The core−shell cathodes demonstrate improved cycling performance at 55 °C even up to 4.5 V when compared to the FCG core-only cathode. Shells of low nickel content and a thickness of ∼300 nm provide sufficient surface stability, particularly at elevated temperatures. We suggest this novel core−shell structure as a suitable cathode for power sources such as electric vehicles, where safety and energy density are equally important.

High‐energy electrode materials are under worldwide development for rechargeable lithium batteries to be used in electric vehicles and other energy storage applications. High capacity and energy density are readily achievable using Ni‐rich Li[Ni1‐xMx]O2 (x = 0.1–0.2, M = Ni, Co, Mn, and Al) cathodes. Unfortunately, their structural instability is associated with severe capacity fading on cycling, which hinders practical applications. Here, a method is presented for producing a continuous compositional change between Li[Ni0.8Co0.2]O2 (center) and Li[Ni0.8Co0.01Mn0.19]O2 (surface) in a spherical particle, resulting in an average composition of Li[Ni0.8Co0.06Mn0.14]O2. The chemical composition in the particle is gradually altered by decreasing the Co concentration while adding Mn content. The Ni content remains fixed. Coin cells with the solid‐solution cathode deliver a specific capacity over 210 mAh g−1 in the voltage range of 2.7–4.3 V vs. Li/Li+ with capacity retention of 85% over 100 cycles at 25 and 55 °C. The main exothermic temperature upon heating appears at around 250 °C with relatively low heat generation (810 J g−1). The presence of the tetravalent Mn at the particle surface is mainly responsible for the high capacity upon cycling and excellent thermal properties.

We successfully synthesized a safe, high-capacity cathode material specifically engineered for EV applications with a full concentration gradient (FCG) of Ni and Co ions at a fixed Mn content throughout the particles. The electrochemical and thermal properties of the FCG Li[Ni(0.54)Co(0.16)Mn(0.30)]O2 were evaluated and compared to those of conventional Li[Ni(0.5) Co(0.2) Mn(0.3)]O2 and Li[Ni(1/3)Co(1/3)Mn(1/3)]O2 materials. It was found that the FCG Li[Ni(0.54)Co(0.16)Mn(0.30)]O2 demonstrated a higher discharge capacity and a superior lithium intercalation stability compared to Li[Ni(0.5) Co(0.2)Mn(0.3)]O2 and Li[Ni(1/3)Co(1/3)Mn(1/3)]O2 over all of the tested voltage ranges. The results of electrochemical impedance spectroscopy and transition-metal dissolution demonstrate that the microstructure of primary particle with rod-shaped morphology plays an important role in reducing metal dissolution, which thereby decreases the charge transfer resistance as a result of stabilization of the host structure.