High‐Capacity Cathode Material with High Voltage for Li‐Ion Batteries

Abstract

Electrochemical energy storage devices with a high energy density are an important technology in modern society, especially for electric vehicles. The most effective approach to improve the energy density of batteries is to search for high-capacity electrode materials. According to the concept of energy quality, a high-voltage battery delivers a highly useful energy, thus providing a new insight to improve energy density. Based on this concept, a novel and successful strategy to increase the energy density and energy quality by increasing the discharge voltage of cathode materials and preserving high capacity is proposed. The proposal is realized in high-capacity Li-rich cathode materials. The average discharge voltage is increased from 3.5 to 3.8 V by increasing the nickel content and applying a simple after-treatment, and the specific energy is improved from 912 to 1033 Wh kg . The current work provides an insightful universal principle for developing, designing, and screening electrode materials for high energy density and energy quality.

Suppressing Surface Lattice Oxygen Release of Li‐Rich Cathode Materials via Heterostructured Spinel Li4Mn5O12 Coating

“…As lithium‐ion batteries (LIBs) conquered the communication and consumer electronic world and further marched to electric vehicles and renewable energy storage grids, imperious demand in the energy density has spurred ongoing search for new high‐capacity electrode materials especially cathode materials . Lithium‐rich layered oxides (LLOs), with a chemical formula x Li 2 MnO 3 ·(1− x )LiMO 2 (M = Ni, Co, Mn) and reversible capacity exceeding 250 mA h g −1 , are considered to be a feasible candidate to fill the need for higher energy density …”

Retarding Phase Transformation During Cycling in a Lithium‐ and Manganese‐Rich Cathode Material by Optimizing Synthesis Conditions

“…These weak peaks should be induced by lithium-cation ordering in the transition-metal layers, which is the feature of the integrated monoclinic Li 2 MnO 3 phase (C2/m). [35,36] Interestingly, the result shows that the cation mixing decreases from 1.97 % (LNCMO-s) to 1.60 % (LNCMO-p), which implies the less migration of the Ni 2 + ions from 3a octahedral sites of the TM slab to the 3b octahedral sites of the lithium slab in LNCMO-p (Figure 2e,f). Owing to the close ionic radii of Li + (0.72 Å) and Ni 2 + (0.69 Å), a fraction of Li + sites are occupied by Ni 2 + and some Ni 2 + sites are taken by Li + , namely, Li/Ni mixing, which blocks the lithium diffusion pathway and increases the barrier for Li + diffusion.…”

Thermal safety studies of high energy density lithium‐ion batteries under different states of charge

“…However, before considering enhanced energy density, the safety of a LIB with a higher‐specific‐capacity material system must be accounted for . Researchers have therefore carried out in‐depth work in this area . Ni‐rich oxides provide a very high specific capacity of approximately 212 mAh g −1 with a Ni:Mn:Co ratio of 8:1:1 but suffer inherent impediments to high rate performance due to low Li diffusion rates .…”

“…20,21 Researchers have therefore carried out in-depth work in this area. [22][23][24] Ni-rich oxides provide a very high specific capacity of approximately 212 mAh g −1 with a Ni:Mn:Co ratio of 8:1:1 but suffer inherent impediments to high rate performance due to low Li diffusion rates. 25,26 The latter is caused by cation mixing because of the similar radii of Li + (0.076 nm) and Ni 2+ (0.069 nm), which leads to a higher activation energy barrier and structural instability.…”