Preparation Of Porous-Carbon-Based Composite And Its Use In Lead-Carbon Batteries

Greenhouse gases emitted by fuel vehicles are believed to exert a certain environmental impact that would not be underestimated.In 2020,China released guidance to achieve carbon peaking and carbon neutrality goals.To this end,extensively using renewable energy for power generation,and gradually driving hybrid electric vehicles（HEV）in place of fuel vehicles are considered to work well.However,the powertrain system of HEV cannot meet the needs of drivers,especially in power batteries.Lead-carbon batteries are privileged in all types of batteries for high safety,affordable mounting cost,and a full set of recovery and reuse systems.Despite this,Lead-carbon batteries also have a weak point that cannot be neglected:under high-rate partial-state-of-charge（HRPSOC）,it may easily generate large particles of Pb SO₄ and cause irreversible sulphating,resulting in poor reversibility.Severe hydrogen evolution may occur due to the low overpotential of hydrogen evolution with the carbon material as a component of negative active material（NAM）.As a result,the electrolyte in batteries will gradually lose water and cause adverse effects to multiple cycles of batteries.To address irreversible sulfating and hydrogen evolution in Lead-carbon batteries,the top agenda is to prepare negative additives featuring affordable cost and high performance.In this paper,the porous carbon（PC）was prepared by the non-customary method,using Ni²⁺for catalyzing and KOH for forming pores,and with cation exchange resin-treated as the carbon source.Next,the PC was further modified to improve the weak points of carbon material and derive a new porous-carbon-based material.After being added to NAM,the porous-carbon-based material can be believed to be the best negative additive as proven in several performance tests in respect of capacity and different rates.This work is expected to inspire the use of Lead-carbon batteries in HEV.The main contents are described below:PC was prepared by catalytic cracking,pyrrole（Py）was polymerized on the surface of PC,and nitrogen groups-enriched porous carbon（PPy@PC）was prepared by pyrolysis.Poly-pyrrole（PPy）maintains good stability under acidic condition.Combining an appropriate amount of PPy with PC is beneficial to suppress hydrogen evolution.In addition,the material also has the unique structure of PC,which can build a conductive network in NAM and delay the formation of large particle size lead sulfate.Therefore,PC was coated with PPy here and the effects of different compositing ratios on cells were considered.The surface of PPy@PC-1 material was found smoother;It effectively delays the occurrence of irreversible sulfation.It is better for cells.The discharge specific capacity of the NAM with PPy@PC-1 material is up to173.3 m A h g^-1,a significant increase compared to CB NAM(150.7 m A h g^-1).Under HRPSOC,the PPy@PC-1 cell cumulatively has 4338 cycles,equivalent to 4.7 folds of the CB cell.With Pb C₄H₆O₄·3H₂O treated as the lead source,CO₃^2-derived from Na₂CO₃ was mixed with PC,then Pb@PC was prepared by pyrolysis.Lead is an essential substance in lead-carbon batteries and a metal element,so modifying carbon materials with lead cannot introduce new impurities but also inhibit hydrogen evolution.Therefore,Pb@PC was prepared by pyrolysis here and its effects on the negative performance of cells were observed.Pb@PC prepared by pyrolysis was found to contain hydrophilic groups and there were chemical bonds between Pb and PC.These properties would facilitate the homogeneous dispersion of Pb@PC in NAM.This is beneficial to delay the occurrence of irreversible sulfation.The specific discharge capacity of Pb@PC NAM at 0.1C is up to 175.1 m A h g^-1,an increase of 16.5%compared to the CB cell(150.3m A h g^-1).Under HRPSOC,the Pb@PC cell can reach 4857 cycles,compared to only 913 cycles of the CB cell.