A Perspective on the Sustainability of Cathode Materials used in Lithium‐Ion Batteries

Abstract

tation currently accounts for 23% of global energy-related CO 2 emissions. [1] Electric vehicles (EVs) thus represent a rapidly expanding market, with at least 20% of road vehicles estimated to be electrically powered by 2030. [1] LIB technology takes great prominence within the automobile industry, due to its unbeatable electrochemical performance and lightweight, portable nature. Its impressive performance can be attributed, in part, to the low weight and small ionic radius of the Li + ions (0.76 Å), allowing fast ion transport. This fast transport, along with its low reduction potential (-3.04 V vs standard hydrogen electrode (SHE)), [2] allows for high power density as well as volumetric and gravimetric capacity. Such properties are of critical importance for EVs. [3] With the increased demand for high energy density LIBs for EVs, comes reductions in battery cost and subsequent volatility in material supply. In light of the immense scale of transport electrification that is being proposed in order to meet CO 2 emission targets, considerable attention is being directed toward the socioenvironmental and economic impact of such an increase in material demand. Of particular focus are lithium-ion cathode materials, many of which are composed of lithium (Li), nickel (Ni), manganese (Mn), and cobalt (Co), in varying concentrations (Figure 1a). The cathode constitutes more than 20% of LIB's overall cost and is a key factor in determining the energy and power density of the battery (Figure 1b). [3,4] It is, therefore, vital to maximise the cathode's performance while minimizing its cost, to make EVs more accessible for society.The high cost of cathode materials is largely attributed to the presence of cobalt-a rare and expensive element mined primarily in the Democratic Republic of the Congo (DRC)-which has been deemed necessary in the past to deliver high energy densities in LIBs. For example, the active material within the commercial NMC111 cathode (LiNi 0.33 Mn 0.33 Co 0.33 O 2 ) costs ca. £17 kg −1 , producing 3.88 kWh kg −1 . [5] This high cost is largely attributed to the relatively large amount of cobalt within the electrode (£ 25 kg −1 ). [6] This cost is over 350 times greater than that of iron (£0.068 kg −1 ), [7] which reflects its relative high natural abundance. A combination of political instability within the DRC, social impacts within the mining sector, and supply chain volatility and ambiguity have driven a decrease in cobalt content in NMC cathodes (e.g., going from NMC 111 to NMC811 (LiNi 0.8 Mn 0.1 Co 0.1 O 2 )) and zero-cobalt alternatives such as LiNi 0.5 Mn 1.5 O 4 spinels, LiMO 2 disordered rocksalts and Electric vehicles powered by lithium-ion batteries are viewed as a vital green technology required to meet CO 2 emission targets as part of a global effort to tackle climate change. Positive electrode (cathode) materials within such batteries are rich in critical metals-particularly lithium, cobalt, and nickel. The large-scale mining of such metals, to meet increasing battery demands, poses con...

In Situ Electrochemical Regeneration of Degraded LiFePO4 Electrode with Functionalized Prelithiation Separator

“…[7] Among various batteries, LiFePO 4 (LFP) power batteries, mainly applied in the fields of EVs and smart grids, have indispensable market and prolonged flourish due to their cost, safety, and durability advantages over layered Li transitionmetal oxides. [8][9][10] With the fast-growing number of EVs worldwide, million tons of LFP batteries reaching their end of life are to be handled and disposed properly. [11] In recent studies, great efforts have been devoted to recycling the spent LFP batteries, detailing in recovery of valuable elements and re-synthesis of new LFP cathode materials.…”

Lithium Battery Model and Its Application to Parallel Charging

“…Ternary lithium batteries adopt layer oxide cathode material such as lithium nickel-cobalt-manganese (NCM: LiNi 1−x−y Co x Mn y O 2 ) and lithium nickel-cobalt-aluminum (NCA: LiNi 1−x−y Co x Al y O 2 ). The advantages of using ternary cathodes are high specific capacity, low internal resistance, and good structural stability [15]. By increasing the nickel content in ternary cathode materials, their specific capacity can be boosted to over 200 mAh g −1 (NCM811 or NCM955) [15], which are very popular in advanced EV batteries.…”

“…The advantages of using ternary cathodes are high specific capacity, low internal resistance, and good structural stability [15]. By increasing the nickel content in ternary cathode materials, their specific capacity can be boosted to over 200 mAh g −1 (NCM811 or NCM955) [15], which are very popular in advanced EV batteries. NCA-80 (LiNi 0.8 Co 0.15 Al 0.05 O 2 ), majorly used by Tesla, has a comparable capacity to NCM811, but with better capacity retention and enhanced thermal stability due to the removal of manganese ion dissolution in the electrolyte [15].…”

“…By increasing the nickel content in ternary cathode materials, their specific capacity can be boosted to over 200 mAh g −1 (NCM811 or NCM955) [15], which are very popular in advanced EV batteries. NCA-80 (LiNi 0.8 Co 0.15 Al 0.05 O 2 ), majorly used by Tesla, has a comparable capacity to NCM811, but with better capacity retention and enhanced thermal stability due to the removal of manganese ion dissolution in the electrolyte [15]. In terms of battery cell types, cylindrical, pouch, and prismatic are three major forms in battery cell manufacturing [16].…”

Air/Water Stability Problems and Solutions for Lithium Batteries

“…In addition to SEs, cathode and anode materials also greatly affect/control the performance of LIBs [17][18][19][20][21][22][23][24]. Up till the present moment, nickel-rich (Ni-rich) layered cathode materials, specifically LiNi x Co y Mn z O 2 (NCM) and LiNi x Co y Al z O 2 (NCA), have gradually emerged as have become one of the most practical and promising cathode materials for LIBs due to their high energy density, large discharge capacity, and low cost [25][26][27].…”