Approaching Ultimate Synthesis Reaction Rate of Ni-Rich Layered Cathodes for Lithium-Ion Batteries

Nickel-rich layered oxide LiNi_(x)Co_(y)MnzO_(2)(NCM,x+y+z=1)is the most promising cathode material for high-energy lithium-ion batteries.However,conventional synthesis methods are limited by the slow heating rate,sluggish reaction dynamics,high energy consumption,and long reaction time.To overcome these chal-lenges,we first employed a high-temperature shock(HTS)strategy for fast synthesis of the NCM,and the approaching ultimate reaction rate of solid phase transition is deeply investigated for the first time.In the HTS process,ultrafast average reaction rate of phase transition from Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_(2) to Li-containing oxides is 66.7(%s^(-1)),that is,taking only 1.5 s.An ultrahigh heating rate leads to fast reaction kinetics,which induces the rapid phase transition of NCM cathodes.The HTS-synthesized nickel-rich layered oxides perform good cycling performances(94%for NCM523,94%for NCM622,and 80%for NCM811 after 200 cycles at 4.3 V).These findings might also assist to pave the way for preparing effectively Ni-rich layered oxides for lithium-ion batteries.

Boosting cycling stability by regulating surface oxygen vacancies of LNMO by rapid calcination

Spinel LiNi_(0.5-x)Mn_(1.5+x)O_(4)(LNMO)has attracted intensive interest for lithium-ion battery due to its high voltage and high energy density.However,severe capacity fade attributed to unstable surface structure has hampered its commercialization.Oxygen vacancies(OVs)tend to occur in the surface of the material and lead to surface structure reconstruction,which deteriorates the battery performance during electrochemical cycling.Here,we utilize high-temperature-shock(HTS)method to synthesize LNMO materials with fewer surface OVs.Rapid calcination drives lower surface OVs concentration,reducing the content of Mn^(3+)and surface reconstruction layers,which is beneficial to obtain a stable crystal structure.The LNMO material synthesized by HTS method delivers an initial capacity of 127 mAh·g^(-1) at 0.1 C and capacity retention of 81.6%after 300 cycles at 1 C,and exhibits excellent performance at low temperature.

Recycle spent graphite to defect-engineered,high-power graphite anode

Graphite is a dominant anode material for lithium-ion batteries(LIBs)due to its outstanding electrochemical performance.However,slow lithium ion(Li+)kinetics of graphite anode restricts its further application.Herein,we report that high-temperature shock(HTS)can drive spent graphite(SG)into defect-rich recycled graphite(DRG)which is ideal for high-rate anode.The DRG exhibits the charging specific capacity of 323 mAh/g at a high current density of 2 C,which outperforms commercial graphite(CG,120 mAh/g).The eminent electrochemical performance of DRG can be attributed to the recovery of layered structure and partial remaining defects of SG during ultrafast heating and cooling process,which can effectively reduce total strain energy,accelerate the phase transition in thermodynamics and improve the Li+diffusion.This study provides a facile strategy to guide the re-graphitization of SG and design high performance battery electrode materials by defect engineering from the atomic level.