Extraordinary Ultrahigh-Capacity and Long Cycle Life Lithium-Ion Batteries Enabled by Graphitic Carbon Nitride-Perylene Polyimide Composites

Graphitic carbon nitride(g-C_(3)N_(4))is widely used in organic metal-ion batteries owing to its high porosity,facile synthesis,stability,and high-rate performance.However,pristine g-C_(3)N_(4)nanosheets exhibit poor electrical conductivity,irreversible metal-ion storage capacity,and short-term cycling owing to their high concentration of graphitic-N species.Herein,a series of 3,4:9,10-perylenetetracarboxylic diimide-coupled g-C_(3)N_(4)composite anode materials,CN-PI_(x)(x=0.2,0.5,0.75,and 1),was investigated,which exhibited an unusually high surface nitrogen content(23.19-39.92 at.%)and the highest pyridinic-N,pyrrolic-N,and graphitic-N contents reported to date.The CN-PI_(1)anode delivers an unprecedented and continuously increasing ultrahigh discharging capacity of exceeding 8400 mAh g^(-1)(1.96 mWh cm^(-2))at 100 mA g^(-1)with high specific energy density(E_(sp))of~7700 Wh kg^(-1)and the volumetric energy density(E_(v))of~14956 Wh L-1 and an excellent long-term stability(414 mAh g^(-1)or 0.579 mWh cm^(-2)at 1 A g^(-1)).Furthermore,the activation of the CN-PI_(x)electrodes contributes to their superior electrochemical performance,resulting from the fact that the Li+is not only stored in the CN-PI_(x)composites but also CN-PI_(x)activated the Li^(0)adlayer on the CN-PI_(1)-Cu heterojunction as an SEI layer to avoid the direct contact of Li^(0)phase and the electrolyte.The CN-PI_(1)full cell with LiCoO_(2)as the cathode delivers a discharge capacity of~587 mAh g^(-1)at a 1 A g^(-1)after 250 cycles with a Coulombic efficiency nearly 99%.This study provides a strategy to develop N-doped g-C_(3)N_(4)-based anode materials for realizing long-lasting energy storage devices.

High‑Defect‑Density Graphite for Superior‑Performance Aluminum‑Ion Batteries with Ultra‑Fast Charging and Stable Long Life

Rechargeable aluminum-ion batteries(AIBs)are a new generation of low-cost and large-scale electrical energy storage systems.However,AIBs suffer from a lack of reliable cathode materials with insufficient intercalation sites,poor ion-conducting channels,and poor diffusion dynamics of large chloroaluminate anions(AlCl4−and Al2Cl7−).To address these issues,surfacemodified graphitic carbon materials[i.e.,acidtreated expanded graphite(AEG)and base-etched graphite(BEG)]are developed as novel cathode materials for ultra-fast chargeable AIBs.AEG has more turbostratically ordered structure covered with abundant micro-to nano-sized pores on the surface structure and expanded interlayer distance(d002=0.3371 nm)realized by surface treatment of pristine graphite with acidic media,which can be accelerated the diffusion dynamics and efficient AlCl4−ions(de)-intercalation kinetics.The AIB system employing AEG exhibits a specific capacity of 88.6 mAh g^(−1)(4 A g^(−1))and~80 mAh g^(−1) at an ultra-high current rate of 10 A g^(−1)(~99.1%over 10,000 cycles).BEG treated with KOH solution possesses the turbostratically disordered structure with high density of defective sites and largely expanded d-spacing(d002=0.3384 nm)for attracting and uptaking more AlCl4−ions with relatively shorter penetration depth.Impressively,the AIB system based on the BEG cathode delivers a high specific capacity of 110 mAh g^(−1)(4 A g^(−1))and~91 mAh g^(−1)(~99.9%over 10,000 cycles at 10 A g^(−1)).Moreover,the BEG cell has high energy and power densities of 247 Wh kg^(−1) and 44.5 kW kg^(−1).This performance is one of the best among the AIB graphitic carbon materials reported for chloroaluminate anions storage performance.This finding provides great significance for the further development of rechargeable AIBs with high energy,high power density,and exceptionally long life.