Enhanced Cyclability and High-Rate Capability of LiNi_0.88Co_0.095Mn_0.025O₂ Cathodes by Homogeneous Al³⁺ Doping

Abstract

To suppress capacity fading of nickel-rich materials for lithium-ion batteries, a homogeneous Al3+ doping strategy is realized through tailoring the Al3+ diffusion path from the bulk surface to interior. Specifically, the layered LiNi0.88Co0.095Mn0.025O2 cathode with the radial arrangement of primary grains is successfully synthesized through optimization design of precursors. The Al3+ follows the radially oriented primary grains into the bulk by introduction of nano-Al2O3 during the sintering process, realizing the homogeneous Al3+ distribution in the whole material. Particularly, a series of nano-Al2O3-modified LiNi0.88Co0.095Mn0.025O2 are investigated. With the 2% molar weight of Al3+ doping, the capacity retention ratio of the cathode is tremendously improved from 52.26 to 91.57% at 1 C rate after 150 cycles. Even at a heavy current density of 5 (&10) C for the LiNi0.88Co0.095Mn0.025O2–Al2% cathode, a high reversible capacity of 172.3 (&165.7) mA h g–1 can be acquired, which amount to the 84.46 (&81.25) % capacity retention at 0.2 C. Moreover, voltage deterioration is significantly suppressed by homogeneous Al3+ doping from the results of median voltage and dQ/dV curves. Therefore, homogeneous Al3+ doping benefited from the radial arrangement of primary grains provides an effective and practical way to prolong lifespan, as well as improves rate performance and voltage stability of nickel-rich ternary materials.

Nano-TiO2 coated single-crystal LiNi0.65Co0.15Mn0.2O2 for lithium-ion batteries with a stable structure and excellent cycling performance at a high cut-off voltage

“…7, S11 and S12 † show that the Nyquist curve is composed of three semicircles and an inclined straight line from high to low frequencies, which in turn represent the impedance of Li + across the solid electrolyte interface (R f ), the electron transport resistance inside the active material (R e ), the electron transport resistance at the interface between the electrode and electrolyte (R ct ), and Warburg impedance (Z w ). 53,54 The equivalent circuit diagram is shown in Fig. 7e.…”

Optimized Al Doping Improves Both Interphase Stability and Bulk Structural Integrity of Ni-Rich NMC Cathode Materials

“…The electrode with 1%Al-NMC76 at 0.2C charging and 5C discharging (Figure B) also maintains 79.2% capacity retention after 500 cycles compared to its initial discharge capacity, while the NMC76 electrode retains only 3.4% capacity. The cycling performance comparison shown in Table S1 indicates that the 1%Al-NMC76 electrode in our work delivers better cycling performance than most of the reported Al-doped, Ni-rich NMC cathodes even at the high-voltage operation and high rate cycling. ,,− Figures C,D show the detailed charge/discharge voltage profiles from cycles 1–300. Pristine NMC76 exhibits a dramatic decrease in capacity and a discharge voltage plateau as cycling proceeds.…”

Designing positive electrodes with high energy density for lithium-ion batteries

“…Indeed, various cations and anions (such as B, F, Mg, and Al) have been investigated as dopants for positive-electrode materials with high energy density, all of which improved capacity retention during charge/discharge cycling. [71][72][73][74][75][76][77]92,93,102,103,[106][107][108][109][169][170][171][172][173] For example, doping B into a nickel-rich layered oxide was reported to increase capacity retention aer 100 cycles from 83% to 92% by suppressing crack formation. 92…”